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HARRY S 
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is to be enlarged until capable of meeting the requirements of the present naval units 
and of those to be constructed in the period 1949-53; the Brazilian Navy is also at — 
manufacturing US-type five-inch naval guns and ammunition. 
Brazil has sufficient tetxile manufacturing and food-processing installations 
to supply her own needs; Brazilian-manufactured personal equipment is of acceptable — 
quality by US standards. 
Certain medical supplies, and most specialized engineer and 
signal equipment, will have to be imported for some time to come. 
Brazilian industry is particularly vulnerable to air attack by carrier-based 
aircraft, because of its concentration along the coast in the Sao Paulo-Rio area. 
The 
possibility of such an attack occurring, however, would be much diminished by the 
presence of friendly land-based air strength on the Brazilian Bulge, even though this 
strength is so located primarily for the protection of the southern trans-Atlantic air 
routes and of the southern approaches to the Caribbean area. 
The possibility of 
sabotage by enemy secret agents and/or radical labor elements is enhanced because 
the small size of the industrial area makes it easigr for saboteurs to operate directly 
under the supervision of one person or centralized cell or headquarters. 
It is believed, 
however, that Brazilian state police, with, if 
are com- 
petent to minimize acts of ore 
d. Science. 
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_ 
Brazilian capabilities tn the field of scientific warfare are extremely limited, 
; & 
and its scientific energies have to date been directed mainly toward improving agricul- 
* 
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ture and developing industries. ‘The Army Technical School, it is true, offers various 
ye me 
relatively modern and comprehensive courses in the fields of electronics and nuclear 
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| 
physics, but the Brazilian Government has neither the trained scientists nor the plant 
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or laboratory facilities necessary for conducting independent research. 
Of 166 na- 
tional institutes, the University of Sao Paulo has the greatest potential in electronics; 
university authorities hope that a betatron, manufactured in the US, will be in opera- 
tion before the end of 1948. 
The National Institute of Technology in Rio, created to 
perform duties similar to those of the United States Advisory Research Service, is 
probably second in potentialities, but at present is engaged primarily in testing work 
and does little or no research. 
Brazil has attempted to import German scientists 
and has Brazilian scientists studying abroad. 
Such training as may be incidental 
az 
to industrial expansion and air developments may help to bring out scientists and 
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technicians whose services can be utilized for research in the field of scientific war- 
. 
| 
fare. 
The presence of large deposits of thorium-bearing monazite sands along the 
Z 
coast of Brazil also may stimulate an interest in the development of atomic energy. 
1- > 
It is, however, improbable that Brazil will be in a position to produce the weapons 
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of scientific warfare for some time to come. 
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Considering the probable continuance of military influence in the govern- 
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ment, it can be anticipated that Brazilian military expenditures will not be severely 
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cut, and that the country will be in a better position to maintain a sizeable armed 
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force than the other Latin American countries with the possible exception of Argentina. 
It is doubtful, however, that present already substantial military expenditures—about 
35 percent of the total budget of the federal government in 1947—could be increased — 
- without economic disaster for the country as a whole. 
Until, therefore, Brazil’s po- 
tentially very great natural resources are developed far beyond their present exploita- 
tion, this nation could engage~in total war only with financial support from outside. 
| 
3. 
Bastc 
Pouicres AND PRACTICES. 
a. 
Mission. 
| 
In line with the historical development of Brazilian policy sketched in Section 
1, (pp. 49, 50) above, it may be assumed that the Brazilian military establishment at 
present has a five-fold mission: (1) the maintenance of internal security; (2) the pre- 
servation of its territorial integrity and its national prestige among the nations of the 
Western Hemisphere (with special regard for its relative strength vis-a-vis that of Ar- 
gentina); (3) protection of its vital and extremely vulnerable coastal shipping lanes 
in case of a general conflict and furnishing containing and delaying action until as- 
- 
sistance arrives in the event of a major extra-Hemisphere invasion; (4) provision of 
facilities for Western Hemisphere forces in a general conflict, such as air bases, major 
| 
naval installations, and staging areas; and (5) provision of an expeditionary force 
- for overseas operations. The first four aspects of the mission presumably enter into 
_ peacetime plans, while the fifth would come into effect _ in case of a major war. 
b. 
General Military Organization. 
The President is the Commander in Chief of the Brazilian Armed Forces; the 
forces—army, navy, air—operate under three separate cabinet departments headed 
by ministers, generally military men. 
There are no titular “commanders in chief” of 
the forces; next senior in authority to the ministers are the chiefs of staff of the three 
forces, these officials being selected in the light of various qualifications, such as ability, 
prestige, politics, length of service, and relative rank. A bill providing for a complete 
merger of the armed forces under a single ministry has been under consideration for 
some time, and its passage is anticipated. 
Under the present organization, the top directive and advisory bodies are 
the National Security Council, the Joint General Staff, and the Military Cabinet. 
The National Security Council is composed of the President of the Republic, the minis- 
ters and the chiefs of staff of the three forces, and the Chief of the Military Cabinet. 
It considers broad problems of national defense and coordinates civilian and military 
agencies. 
In the event of realization of the contemplated merger of the three forces 
under one cabinet minister, the National Security Council will probably be eliminated, 
and its functions taken over by the Joint General Staff. 
The Joint General Staff is composed of a chief appointed by the President from 
one of the three services—at present the chief is an army general—and a representa- 
tive from each of the other two forces, all of whom must have graduated from the Navy 
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War School command course or the general staff course of the army, navy, or air force; 
civilians also may be appointed to serve on the staff at the President’s discretion. 
The 
_ 
Staff prepares and executes “i and —— exercises for the army, navy, and 
air force. 
The Military Cabtaet serves as the President’s personal military staff, is ap- 
pointed by the President, and includes a representative from each of the three forces. 
The senior officer is the chief of the cabinet and also ez officio secretary of the Na- 
- 
tional Security Council. 
State police forces, fire departments in larger cities, and some other police 
groups, are so organized as to serve in time of war, under the Minister of War, chiefly 
as home-guard forces to relieve other military — from duties concerning internal 
security. 
The army usually takes precedence over the other forces, both because it 
represents the great Dulk of the armed forces (three times the strength of the navy 
and the air forces combined), and because of its long-continued exercise of dominant 
influence in both political and military affairs. 
Brazilian Army combat strength is 57 percent infantry, 18 aciiiad cavalry, 
16 percent artillery, 3 percent armored, and 6 percent miscellaneous. 
Emphasis on 
infantry strength is dictated by the necessity of maintaining garrisons at strategic 
points throughout the country for the preservation of internal order. 
The relatively 
high proportion of cavalry derives from two factors: survival of former strategic con- 
siderations which envisaged cavalry as the main protective arm against invasion from 
the south; and scarcity of motor fuel and lack of highway bridges. 
The present trend— 
which, however, is impeded by shortage of motor fuel—is toward achieving a modern, 
better-balanced, armed force with greater emphasis on motorization. 
' 
The present organization of the Brazilian Navy stresses the utilization of des- 
troyer and destroyer escort vessels, and, secondarily, subchaser and patrol craft. 
Al- 
though the destroyer group may have some offensive capabilities, tactical emphasis is 
on coastal patrol, delaying maneuvers, and limited attacks by stealth. 
Brazil hopes 
to develop a stronger and better-balanced navy by the acquisition of more capital ships. 
_ 
The present organization of the air force lays emphasis on the development 
of light- and medium-bombardment craft with secondary emphasis on fighter craft. 
In general, the Brazilian Air Force is being developed along US lines. 
c. 
Recruitment. 
Compulsory military service has existed in Brazil since 1875, but until very 
recently it was not enforced either universally or equitably, and there was no efficient 
System for the control of military manpower. 
A modern system of active and reserve 
— 
Service adapted to the special economic, social, and military circumstances of Brazil 
was introduced in 1946 and promises to be much more effective than those which 
existed in the past, although military service under the new law is still selective rather 
than universal. 
Every Brazilian male must reniaten 
$ for military service in the first six months 
of the year in which he becomes 17 years of age. 
Volunteers may be accepted by 
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according to the necessities of the respective services in view of their strength as 
authorized by law. 
Service for conscripts and volunteers is one year. 
ing centers; how many actually perform such service is not known. 
In addition, a 
_ 
training schools. _These courses are entirely voluntary, and some last for a period of 
the lower social classes. 
In general they are of low physical stamina and are illiterate, E 
military, naval, and air units 
up to the limit of the vacancies to be filled. The number 
of personnel to be called up is fixed annually by the Ministers of War, Navy, and Air 
An average of 500,000 males become eligible for military service each year; 
however, only 35,000 are accepted for military service in compliance with the present 
quota. 
The quota is broken down into subquotas for the various units, which are 
then filled by drawing by lot on the population residing near unit headquarters. 
All 
other members of the annual class, including a large proportion of the rural popula- 
tion, have the obligation of rendering part-time service in the citizens’ military train- 
certain number of those actually drafted for regular service may be found to be in 
excess of the requirements, and these men form a Repnceens pool sera’ the year 
in which their class is liable for active service. 
| 
- 
‘There appears to.be no set program for training reserves, - though some. fa- 
cilities are provided for this purpose; reserve training centers for officers are dispersed 
strategically throughout the country and the army maintains eleven reserve-officer- 
two years. 
Evidence of Brazil’s desire to increase technical training in all branches of 
military service is seen in the policy of making available to reserves courses which 
hitherto were open only to the regular army. 
: 
The strength of the Brazilian Armed Forces has been set at 172 300. Annual 
conscripts are approximately 35,000. 
The army uses, in relation to its strength, more 
conscripts than does the air force or navy. 
Even in the army, however, an average 
strength of approximately 140,000 seems to indicate that the percentage—25 at the 
maximum—of annual, probably only partly trained, conscripts in the service at any 
one time would not materially affect organization or total efficiency. 
Neither would 
| 
the forces be dangerously reduced—as is the case in other Latin American countries 
whose forces have a larger percentage of conscripts—in the time lapse between the 
discharge of one conscript class and the calling-up of.the next. There are no figures 
available to indicate the average length of service of volunteer a 
d. 
Armed Force Personnel. 
As a group, Brazilian officers are intelligent, A and loyal, and are 
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generally more inclined than their Argentine counterparts toward friendliness and “am 
a lack of arrogance in official and social relations. They are generally drawn from 
“4 
the middle and upper brackets—considering financial and social background—but the 
majority comes from the middle-class. 
A fair proportion of the ores ¢ officers © 
are usually from old and socially prominent families. 
. 
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The enlisted personnel are of mixed racial stock and are generally drawn from : 
but are responsive to discipline, adaptable to training, and loyal to their superior officers. : 
The promotion system is well established. 
In the army, an officer is given « 
a number on .the promotion list when he receives his commission and, as vacancies @ 
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its buying power in the 
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Compared to that in the US, but, compared to 
© Personnel on a middle-class Social standard. Air — to maintain the 
additional allowance for fi 
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occur, he is promoted to the next higher grade. 
Thig system is supposed to be effective 
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for all grades: in Practice, however, there are many exceptions; some Promotions are 
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made for merit; each branch of the Service has its Separate promotion list; many Officers 
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temporarily Separated from the Service for revolutionary activities or other reasons and 
later re-instateg are adjusted on a Separate promotion list AS 
result of al! these 
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factors many classmates hold very different ranks 
In the command echelon and in 
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politica] Positions, an Officer is usually chosen for merit, Performance, ang position 
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on the Promotion list, but politics Play a considerable part in assessing merit. 
There 
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is @ promotion commission which is @ specia] agency in the Ministry of War. 
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Enlisted men are Promoted on the basis of satisfactory completion of per- 
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tinent examinations and/or Schools, existing vacancies, and recommendations of the 
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commanding officers 
The enlisteq Promotion system appears to be fairly and ef- 
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ciently handled. 
Enlisted men may attend schools to receive commissions 
The pro- 
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Brazilian military schools are located for the most part in the vicinity of Rio 
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de Janeiro and are grouped in large training ang instruction installations. 
Schools 
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rate from good to excellent; improvements have been rapid under the Suidance of the 
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Joint Brazil-ug Military Commission and the US Naval Mission. 
There is no war 
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College, but plans for the establishment of one are under consideration. 
Each of the 
three forces has its Seneral staff school, giving comprehensive three-year courses 
covering advanced tactics logistics, and combined arms, and including up-to-date 
doctrine. 
The curricula of the Military and Naval Academies and of the School 
| 
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a Aeronautics are patterned after those of the US service academies; courses in theory — 
_— 
are excellent: those in practical work are becoming more adequate but are hampered 
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by the lack of equipment. 
There are eleven reserve training Centers for Officers. 
The 
| 
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technical Schools, such as Signal, medical-corps, and motor-transport, for Soldiers and 
| 
officers, are considered very good. The Sergeants’ School in Rio trains enlisted men 
| 4 ; 
for the next higher grade and in the use and maintenance of their own weapons and 
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“quipment. 
Enlisted men may become officers by attending any of the Preparatory 
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Schools and entering the Military Academy. 
‘Foreign influence on Brazilian training has been 
“xercised by two countries 
|
US influence began with the Brazilian Navy, in cooperative activities during World 
War I. AUS naval mission has been in Brazil since 1922 with only a two-year lapse, 
and has been the dominant factor in the training and development of the Brazilian 
. 
Navy. 
Operations under the US Fleet in World War II further brought Brazilian naval 
practice in line with that of the US Navy. US Army and Air Force influences began 
with a small general-staff and coast-artillery mission in 1936, and became dominant 
_ with the establishment of a military and military-aviation mission in 1941. 
This mis- 
sion was replaced in 1942 by the Joint Brazil-US Military Commission, which, with sec- 
tions both in Washington and Brazil, supervised the training and preparation of the 
Brazilian Expeditionary Force for participation in World War II, and has continued 
active. 
Prior to 1941 the Brazilian Army had made little progress toward modern- 
ization; now it is as much a counterpart of the US Army as local conditions and avail- 
ability of US equipment permit. 
= 
Additional impetus has been given the Brazilian military training program 
| 
by opportunity for study ih the US. 
Since 1939 about 400 Brazilian army officers 
have been trained in US army schools. 
From 1941-45 a total of 1,131 enlisted naval 
personnel were trained at naval activities in the US, and in August 1946, 136 officers 
and enlisted men were in training in 16 different naval activities. 
Since 1941 the US 
Air Force has trained more than 300 Brazilian pilots and more than 600 aircraft 
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technicians at air force schools in the US. Technicians include photographers, meteor- 
| 
ologists, and communications and maintenance experts. 
: 
Brazilian garrison and field training is modeled after that of the US. Maneu- 
vers on the division scale are held annually, and occasionally of larger units. 
Com- 
bined-arms training courses are given in the General Staff School; in 1947, in addition 
to divisional maneuvers in the various army areas, a combined-arms problem, involv- 
ing army, navy, and air forces in a coastal assault, was carried out near Rio. 
f. 
Mobilization. 
Present army mobilization plans call for the induction of reserves by cate- 
gories into the existing units of the military regions in which they reside. 
The first 
category of trained reserves would be used to bring existing units to war strength 
- 
and replace soldiers cadred out to form new units. The second and third category 
reservists would be used in succession in the same manner. 
It is estimated that all 
the first category could be inducted by M-Day plus 90, but that less than 75 percent 
of these could be equipped, and there would be a serious shortage of trained officers to 
command them. 
| 
g. 
Fiscal. 
Each of the three forces prepares for the President an estimate of the amount 
of money desired for the coming year, to be included in the budget presented to Con- 
+} 
gress by the President. 
At the end of the fiscal year, any deficit is met by the Treasury 
B 
by extra-budgetary and usually unfinanced credits; any excess is returned to the Treas- 
# 
ury. 
During World War II there was a secret emergency war budget estimated to 
be larger than the total budget for national defense, but it is believed that there is no 
secret — at present. 
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Logistics. 
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In the army, supply is controlled by three groups, each immediately respon- 
sible to the Minister of Wars The General Staff determines characteristics and ap- 
proves standard models; the Technical and Production Department fixes technical 
specifications; the General Administrative Department acquires or receives, directly or 
through subordinate offices, all necessary materials. 
The General Administrative De- 
partment is also responsible for organizing depots for materials and for superintend- 
ing storage; storage depots are maintained in each of the ten military regions, but each 
branch distributes supplies pertaining to its particular function. 
The system for main- 
tenance and repair of equipment and for evacuation of personnel and equipment is 
based on that of the US, and was used by the Brazilian Expeditionary Force in World 
War lI. The Requisition Commission of the Minister of War, a fact-finding and plan- 
ning agency responsible for preparing data and plans for requisitions in time of war, ‘ 
does not enter into peacetime procurements. 
In the air force, logistical planning and control is a function of the 4th 
_ 
Division of the Air General Staff—corresponding to the A-4 Section of the US Air 
Force—which studies and regulates the organization and functioning of the supply 
service, and is charged also with the mobilization of transportation, industry, and 
matériel. 
Procurement and distribution are handled by the Directorates of Matériel 
and. _Intendencia. 
The Directorate of Matériel handles the procurement, storage, and 
distribution of ordnance and technical supplies; the Subdirectorate of Aeronautical 
_ 
Technology superintends the technical services, factories, depots, and shops of the 
air force. 
The Directorate of Intendencia is charged with administrative and financial 
services and quartermaster functions, such as procurement and distribution of uniforms, 
individual equipment, subsistence, and practically all non-technical supplies. 
The 
Directorates of Matériel and Intendencia may purchase on special requisition and with- 
out previous authorization of the Air Minister items such as aircraft, vehicles, and 
ordnance matériel. 
Local storage and distribution are handled by appropriate service 
sections of the air-zone commands (see Section 4 c, p. 64). The Brazilian Air Force 
is not known to have developed an air evacuation system and no information is avail- 
— 
me on its supply. ——— for combat operations. 
i. 
Intelligence and Counter-Intelligence. 
Brazil has the usual diplomatic representatives—ambassadors, ministers, at- 
tachés, etc.—in major centers abroad, who apparently do a creditable job of routine 
reporting. 
Military and economic missions, liaison, courtesy and diplomatic visits, 
and students in foreign countries, also may be expected to serve its intelligence — 
| 
when and where possible. 
Brazil has four main intelligence arms—the Military, the Naval, and the 
Air Intelligence Services, and the Federal Directorate of Public Security. 
The last- 
- 
mentioned, while not a military agency (it is under the Minister of the Interior) and 
while it combines police and intelligence duties, has important national-defense func- 
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tions in relation to intelligence and in fact is a much more important organization 
than the armed-force intelligence services. 
In addition, Brazilian bureaucrats have 
been known to have intelligence agencies of their own. 
| 
The Military Intelligence organization is the second section of the Army 
General Staff; its headquarters provides for direct and counter-intelligence, while the 
local offices handle chiefly cartographic activities; Military Intelligence has at various 
times been in conflict with the representatives of the Federal Directorate of Public 
Security, but there have also been examples of excellent cooperation. 
Naval Intelli- 
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gence is believed to be chiefly interested in the collection of operational information. 
: 
Air Intelligence apparently engages only in normal operational intelligence activities. 
i 
Each of the forces has a section in its ministry for dealing with Communism. 
Also, 
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the Anti-Communist Intelligence System, separate from existing army intelligence, 
a 
has recently been organized to combat Communism among army personnel; but 
no information is available as to its exact method of operation. 
It is also believed 
that the Military, Naval, and Air Intelligence services have secret intelligence police. 
O. 
The headquarters of the Federal Directorate of Public Security is divided into 
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four main sections: the Political and Social Police Division (political order, social 
 § 
order, arms-control); the Technical Police Division (police-training and improvement 
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of techniques) ; the Maritime and Frontier and Air Police Division (frontier security 
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and the control of foreigners); and the Division of Traffic and Coordination (foreign 
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police liaison, control of telecommunications traffic). 
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tion is substantially duplicated in the field, with the addition of a secret-service section, 
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controlling plain-clothes agents. 
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The Brazilian Radio Monitoring System, Radio Escuta do Brasil, while an 
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auxiliary organization of the Directorate of Public Security, functions under the 
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Director of Telegraphs, who is responsible to the Minister of Transportation and Pub- 
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This system, considered adequate and self-contained, rendered the US 
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valuable services in locating and controlling clandestine enemy transmitters during 
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War II with the censorship of telephone, postal, cable, and radio communications; 
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information as to its present status is not available. 
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The National Department of Information was 
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' Ministry of Justice and Interior, with the mission of coordinating, orienting, and super- 
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intending foreign and domestic propaganda and acting as an auxiliary information 
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unit to this ministry; it controlled theater, radio, sports events, and the press. 
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formation as to its present status is not available. 
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Because national policy dictated close collaboration with the US, Brazilian ae 
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Intelligence as a whole performed incidental services of great value to the US Govern- 
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ment during the war, and it is believed that it will continue to lend cordial cooperation 
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to our own services. 
With the close of the war, the major interest of Brazilian in- 
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neighbors, notably Argentina and Paraguay. 
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Papers: of 
HARRY: S. TRUMAN. 
4, 
ORGANIZATION, STRENGTH, AND DISPOSITION OF THE VARIOUS ARMED FORCES. 
a. 
Army. 
The Minister of War under the President, who is Commander in Chief of 
the Armed Forces), is responsible for all army matters. 
Directly subordinate to the 
Minister of War are the Army General Staff, the General Administrative Department, 
the Technical and Production Department, the Secretariat General of the Ministry 
of War, and other organs and special commissions. 
The General Staff is responsible 
for the elaboration of plans of organization, mobilization, and employment of the 
army, directing all types of instruction for all Army troops, both regular and reserve, 
directing the choice of ordnance and other equipment for times of peace and war, 
and supervising the General Administrative and the Technical and Production angers 
ments. 
~ 
The Brazilian General Staff functions correspond approximately to those 
of the US Army General Staff prior to World War II; functions performed by the US 
Special Staff and by administrative and technical staffs and services are in Brazil 
grouped under the General Administration Department, which is responsible for vir- 
tually all administrative and service functions of the Brazilian Army except for 
technical aspects of procurement (handled by the Technical and Production Depart- 
ment); it has engineer, quartermaster, ordnance, ee. recruiting, remount and 
veterinary, medical, and signal sections. 
All tactical groupings and territorial stehiitiative organizations are subor- 
dinate to the General Staff. 
For purposes of administrative control, Brazil is divided 
into ten military regions. 
Each military region is commanded by a general officer 
and includes the command headquarters, one or more large units (infantry or cavalry 
divisions), troop and service units, recruiting and mobilization organs, schools of 
various categories, and administrative, transportation, and maintenance units. 
For 
tactical purposes only, the ten regions are grouped into four military zones, commanded — 
by lieutenant generals, who are responsible for the inspection and coordination of 
activities of the region commanders, and for preparation of plans for combining FOguEIs 
into theaters of operations. 
; 
The tactical units of the Brazilian Army include six infantry divisions (two 
of which are US-equipped), three cavalry divisions, one armored division (US-equipped), 
two detachments of divisional status, one mixed brigade, seven independent regiments, 
and forty-one independent battalions. 
(The independent battalions include six US- 
equipped field artillery battalions, four US-equipped light tank companies, and a para- 
troop nucleus.) 
Conversion to US tables of organization is being accomplished; present 
composition and strength of units fall, however, somewhat short of US requirements. 
(For example, the average strength of the infantry division is 10,500, as against a 
table-of-organization strength of 14,043, and the cavalry divisions average 7,500 instead 
of 11,676. 
The cavalry divisions are comparable to a US va 
cearmaerty 
brigade with 
a mechanized squadron.) 
The total strength of the Brazilian Army is 140,000, of which about 6,800 are 
_ 
officers. 
The officers have high morale and efficiency and are well trained. 
Many 
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have had the advantage of practical application of staff theory, troop training, and 
combat tactics during training and actual employment of the Brazilian Expeditionary 
_ Force in Italy. Although the physical stamina of the Brazilian soldier is low, his 
training is fairly complete. 
Continued improvement of the service schools and in-— 
creasing emphasis on practical work are producing constantly better trained personnel, 
both enlisted and officer. 
oe 
Brazilian weapons are diesen in number for present one but are, except 
- 
for small arms, largely imported. 
One infantry division and the armored elements 
of the armored division are equipped with US World War II matériel, furnished for use 
of the Brazilian Expeditionary Force. 
Since the war, another infantry division has 
received US equipment under the inter-American allocations program. 
Brazilian- 
manufactured equipment includes revolvers (inferior, as the metal is of poor quality), 
Mauser rifles, machine guns, mortars, and small-arms ammunition. 
No artillery is 
Brazilian-made. 
Matériel, all obsolete, from sources other than US includes German- 
made Mauser rifles and French artillery. 
All fire-control equipment, transport vehicles 
(of modern design), engineer equipment, and demolitions equipment are of US origin. 
The Brazilian Army is at present the largest, best-trained, and best-equipped 
armed force in Latin America. 
While basic qualities of enlisted personnel may place 
- 
Brazil at a disadvantage as compared with Argentina, it is anticipated that Brazil, 
assuming continuance of the US guidance and assistance responsible for its present 
lead, 
should be able to maintain an army at least the equal of any in Latin America. 
b. 
Navy. 
The Minister of the Navy is responsible for all naval matters. 
Directly sub- 
ordinate to the Minister of the Navy is the Naval General Staff. 
With the exception of 
the Hydrographic Office and the Bureau of Communications, which are under the direct 
- command of the Minister, the administrative organization, including the district 
-commandants, is subordinate to the Naval General Staff. 
Brazil is divided into six naval districts with headquarters located at the 
following strategic points; Belém, Recife, Bahia, Rio de Janeiro, Floriandpolis, and 
Ladario. Of these Rio de Janeiro is the most important. 
The districts maintain close 
liaison with one another and are under the command of officers of flag rank who have 
jurisdiction over all naval affairs within their commands. 
‘The tactical organization, also subordinate to the Naval General Staff, in- 
cludes the Fleet and various craft assigned to the naval districts. 
The Fleet is organized 
into a battleship division (one battleship), a destroyer force (consisting of one flotilla 
of three destroyers and one flotilla of eight destroyer escorts), a submarine flotilla, and 
a subchaser flotilla. 
The Amazon River Flotilla and the Mato Grosso Flotilla are 
assigned to the command of the Fourth and Sixth Naval Districts, respectively. Eight 
small vessels assigned to the Hydrographic Office and seven assigned to the Bureau of 
Communications operate directly under the Ministry of the Navy. 
| 
The Brazilian Navy has 78 units, with a total approximate tonnage of 108,000. 
These include one battleship, three destroyers, eight destroyer escorts, eight patrol 
craft, four submarines, sixteen subchasers, and three river monitors, as well as numerous — m= 
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auxiliary vessels. 
(A second battleship 4nd a cruiser were decommissioneg in August 
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The battleship, of 19 200 tons, is Obsolete, in Poor Condition, 
the guns 
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have not been: fired for years, 
The destrovers (1,500 tons) ang destroyer escorts 
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(1,275 tons) are modern according to Latin American Standards (€x-US or built on US 
OF Modified yg designs) and constitute the main Strength of the navy. 
The 
marines are Obsolete. 
The river Monitors are Of shallow draft and Suitable Only for 
| 
river Navigation- they are located at Ladario, On the Upper Paraguay River. 
| 
In addition to these units, six destroyers and three Subchasers are under con- 
struction. The destroyers range from sixty-nine to ninety-five Percent complete: 
‘ 
Cause of Shortage of funds for labor and materia], however, dock trials Of the first 
| 
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Ship are not “xpected before January 1949 
Total active naval personne! Strength of about 16.000 includes 1 
officers: 
& 
in addition, the.Marine Corps has a Strength of Toughly 100 officers ang 4,000 men. 
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The Brazilian Navy reports a reserve Strength of 10,000, Which is not utilized because 
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Tegular naval] rolls are Maintained at a higher figure than actually Tequired. Officer 
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Personnel are Considered low In basic Menta] qualifications but fairly efficient in the 
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The Brazilian Navy has a Sizeable navy yard on Itha das Cobras in the harbor 
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The Nata] base, the 
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staving dock is at a standstill, ang for planning Purposes, this dock Should not be 
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Considered for &t least five years. 
The Navy Yarq on Ilha das Cobras is Superior to 
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those of the rest of Latin America, Which fact may be attributed to the Influence of 
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the Us Naval Mission in Brazil: it has facilities for Making major repairs to naval 
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size, but its facilities for repairing heavy armor are 
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limited. 
The Brazilian Navy is one Of the Significant Navies of Latin America: its 
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strength lies in destroyer forces, all of Which Participated in €scort work during World 
War IT. Although it has 4 strength in major combat vessels—destrover escorts and 
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above—or only 33,900 tons, as compared to Argentina’s 103,000 tons ang Chile’s 40,000, 
| 3 
the superior firing Power, Mobility, speed, and endurance of Brazil’s modern fleet of 
| 
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vessels as Compared With the Older Argentine destroyers neutralizes the advyan- 
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tage Argentina might be thought to have with its Preponderant Strength in heavier 
| 
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vessels. 
The Brazilian Navy is Considereq about equa) in Strength to the Argentine 
. 
Navy, and the six destroyers (totaling 8,040 tons) under Construction Will substan- 
-Ually increase its effectiveness, 
| 
The Air Minister is in command of all 
rectly subordi- 
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Nate to him are 
general Staff, a Cabinet, the 
com- 
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Mands, 
The Air Genera] Staff is Charged With the ormulation of the Strategic con. 
fi} ee 
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Cept of air Warfare and with the logistical ang tactica) Preparations of the air force 
ii) 3 *
for performing its mission, either separately or in conjunction with the other armed 
forces. 
The cabinet is a group of advisers to the Air Minister. 
The air services consist 
of seven directorates for the supervision of personnel, intendencia (administrative, 
quartermaster, and finance services), health services, works, matériel, air routes, and 
— 
civil aeronautics (Brazil’s civit aviation in general is under the direction and control 
of the Directorate of Civil Aviation). “Under a planned reorganization, the Directorate 
of Air Routes of the Air Ministry will have jurisdiction over the organization and opera- 
tion of the federal airways and their services. 
For. purposes of territorial organization, the country is divided geographically 
into five air zones: Northern, Northeastern, East Central, West Central, and Southern. 
For purposes of tactical organization, the air force is broken down into air-zone com- 
mands, groups, squadrons, and air base units. 
Air-zone commands are the high 
command bodies of the Brazilian Air Force and exercise direct authority over forces 
and activities within the geographical limits of the respective zones. 
Under the zone 
commands are groups and squadrons analagous to those of the US Air Force. 
Groups 
comprise one or two squadrons: the awe is the basic tactical unit. 
Base units per- 
form all maintenance. 
As of 1 September 1948, the total military aircraft of 1,133 included 124 fighter 
planes, 16 attack planes, 115 light bombardment planes, 20 reconnaissance planes, 194 
transport planes, 50 liaison planes, and 614 trainer planes. 
In addition there are 
782 civilian aircraft, including aviation club planes. 
Tactical units are 2 patrol squad- 
rons, 2 transport squadrons, 2 light bombardment squadrons, 6 medium bombard- 
ment squadrons, and 3 fighter squadrons. 
Aircraft is almost totally of US manufacture and has been procured since 
1941. 
Brazilian air force equipment is considered efficient; because parts and facilities 
are scarce, however, maintenance is inadequate. 
Although definite information is 
not available, it is estimated that “ from 60 to 70 percent of the combat aircraft 
are operational. 
The total personnel strength of the regular air force is 20,091. 
On 1 Septem- 
ber 1948 air personnel included 1,786 officers (of which 998 are pilots) and 18,305 en- 
listed men. 
In addition, the air force maintains a total of about 2,000 trained civilians 
as a part of its ground establishment. 
Brazilian pilots are probably the best in South 
America. and are considered good when measured by US standards. 
Training is con- 
_ ducted along US lines with the advice of US Air Force personnel. 
Many pilots have 
been trained in the US, and there is a nucleus of combat-seasoned veterans of the 
Brazilian Expeditionary Force who saw service with the US Air Force in Italy. 
Ground 
personnel are also considered the best in South America and have received excellent 
instruction from US civilian instructors both in the US and in Brazil. 
There are 337 air facilities of various types in Brazil—323 airfields, and 14 
facilities for sea planes. 
Of the 323 airfields, only 23, or less than one-tenth, have 
hard-surfaced runways. 
Furthermore, the airfields in general are lacking in naviga- 
tional aids, weather-reporting facilities, and ‘night-flying installations. 
Military air- 
fields of modern-base proportions have been constructed all along the coast of the 
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northern region, mostly with the aid and support of the US Government: 
Three air- 
fields, Val de Cans near Belém, Tirirical near Sao Luiz, and Parnamirim near Natal, 
Support loads of 120,000 lbs. or more and were used as ferry stops or patrol bases during 
World War II. Down the east coast there is one field, Gravatai near Porto Alegre, also 
capable of supporting loads of 120,000 lbs. or more. 
Recent reports indicate that 
maintenance of some of these fields is poor, and in the eventuality of a war they would 
have to be extensively improved before they could be utilized. 
The Brazilian Air Force is the dominant air force in South America and is 
triple the present size and effectiveness of the Argentine Air Force. 
In numbers of 
aircraft and personnel, it ranks within the first ten air powers of the world; however, 
the small proportion of combat craft relegates it to the position of a minor air power 
and limits its activities largely to defensive operations. 
_ Brazil’s long-range offensive 
capabilities are limited to the employment of its patrol bombers. 
Operating from 
bases at Belém, Floriandépolis, Pelotas, and an auxiliary seaplane station at Manaus, 
— 
these aircraft could strike anywhere in South America with the exception of the 
southernmost parts of Argentina and Chile. 
From the southern and southwestern 
bases the range of the tactical bombers extends throughout the River Plate estuary, 
_ including Buenos Aires, all of Uruguay, Paraguay, and the eastern section of Bolivia. 
The operation of short-range craft is limited to the Uruguayan and Argentine border. 
_ 
The utilization of this offensive capacity is limited by the inadequate capacity 
for maintenance (due to the scarcity of parts and facilities), by the considerable logis- 
_ tical problem presented by the activation and employment of the necessary bases, 
and by the lack of mobility resulting from the scarcity of railroads and adequate high-| 
ways and the inadequate air lift capacity. 
It is estimated that the maximum initial 
offensive capacity would not exceed approximately 20 PBY-5’s, 78 light bombers, and 
63 fighters, and that full-scale operations could be sustained for a few weeks only. 
Ability to sustain operations longer would depend on US assistance in all these respects. 
Brazil has a small number of first-line interceptor aircraft and a limited num- 
ber of modern AA guns which probably would be sufficient to protect some important 
centers from air attack by any of her immediate neighbors, but could not be moved - 
to the defense of border areas. 
Air defense is handicapped by the lack of an efficient 
€arly-warning system and effective passive defenses. 
d. 
Distribution of Forces. 
The Brazilian Army is deployed in three major concentrations. 
Of the 140,- 
000 troops, approximately 20,000 are stationed in northern and northeastern Brazil 
with slightly less than 10,000 in the vicinity of Recife; this concentration includes the 
Seventh Infantry Division with headquarters at Recife and the Natal Detachment, and 
~ 
consists for the most part of infantry troops supplemented by artillery. 
The second 
area of concentration, around Rio de Janeiro and Sao Paulo, has approximately 50,000 
troops and includes: the First Infantry Division, the armored division, school troops 
Including the paratroop nucleus, coast and antiaircraft defenses, and service estab- 
lishments, with headquarters at Rio de Janeiro; the Second Infantry Division with 
headquarters at Sao Paulo; and the Santos Detachment of coast and antiaircraft de- 
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More than half of this concentration is infantry troops; the remaining forces 
are fairly evenly proportioned numbers of artillery, armored, and engineer troops. 
The third troop concentration is in the southern area and contains approximately 
60,000 troops, including the First, Second, and Third Cavalry Divisions (25,000 troops) 
with headquarters at Santiago, Uruguaiana, and Bagé, respectively, the Third Infantry 
- 
Division at Porto Alegre, the Fifth Infantry Division with headquarters at Curitiba, and 
several independent units. 
The Fourth Infantry Division with headquarters at Belo 
Horizonte, the Mixed Brigade at Corumbé, and various independent units scattered 
throughout the country account for the remaining 10,000 troops. 
| 
The entire Brazilian fleet is normally located in Rio de Janeiro harbor, except 
for one or two despatch vessels stationed in the ports of Belém, Recife, and Sao Salva- 
dor, and the river monitors located at Ladario on the Paraguay River. 
The Brazilian Air Force squadrons are all located on the coast. 
The First 
and Second Patrol Squadrons are stationed at Belém in the Amazon delta. 
The First 
© 
and Second Light Bombardment Squadrons are based at Sao Paulo. 
The Third and 
Fifth Medium Bombardment Squadrons are located at Natal, and the First, Second, 
Fourth, and Sixth at Recife, Sao Salvador, Fortaleza, and Curitiba, respectively. Fighter 
squadrons are concentrated in the southern sector, the First and Second at Santa 
Cruz near Rio and the Third at Porto Alegre, ee 200 miles north of the 
Uruguayan border. 
e. 
Quasi-Military Organizations. 
Quasi-military forces in Brazil include the Federal District and state military 
police and the fire departments of the larger cities (militarily organized and trained 
but in peacetime under the control of the Minister of Justice in the Federal District 
and the state Secretaries of Justice in the other states). 
Normally, an army officer is 
in command of each of these organizations. 
Although these officers are responsible 
to the above-mentioned civil authorities in time of peace, they are all responsible to 
the Minister of War in time of war, and the units they command are organized and 
trained to serve as “home guard” units to relieve completely the army forces from 
all duties of internal policing and defense against sabotage or enemy attacks in small 
- numbers. The total of all these quasi-military forces is a little under 80,000. While 
some of the organizations are of dubious value, they. would be used to overcome in- 
surrection against the government and do constitute a definite factor in assuring “ia 
the stability of the government. 
It is possible that many of these troops could serve 
in front-line capacities, although they cannot be rated the equal of better trained and 
more unified forces, such as the Chilean Carabineros. 
5. 
GENERAL ESTIMATE OF Minrrary CAPABILITIES. 
a. 
Adequacy of Present Forces. 
Brazilian military forces are estimated (in terms of their presumed mission as 
— = 
stated in Section 3. a., p. 54) to be: (1) adequate for the maintenance of internal 
security; (2) adequate for the maintenance of territorial integrity against attacks by 3 a 
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cations of jealousy occasic 
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with Brazil, and 
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& combination of South American neighbors: (3) not adequate for defense against 
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an attack by a Strong extra-Hemisphere Power; and (4) adequate for the maintenance 
a 
| 
of existing facilities for use of reinforcing Hemisphere troops, 
Brazilian forces also 
! 
have some Offensive Capabilities, 
‘ 
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The Brazilian armed forces are entirely canable of maintaining internal order 
: 
| 
in the country, and it is therefore unlikely that Subversive elements outside the armed 
‘ 
forces coulgq Overthrow or take Possession of a §overnment supported by the Military. 
. ¥ 
While the Possibility of defection within the ranks of the Military cannot be discounteg 
if 
— 
entirely, it is true that the Brazilian Army has senerally acteg aS a unit; the Officers 
id 
have shown themselves Joya] fo their chiefs and the enlisteq men to their Officers, 
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It is therefore improbable that revolt of an officer faction—such 4S occurred in 
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Venezuela in 1944 and was attempted in Paraguay in 1947_wouig break the Solid 
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military front and lead to the overthrow of the S0vernment. 
The Politica] Policy of 
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the army as & whole is quite another Matter; g Military Seizure of Power or q Military 
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intervention between two competing 8Toups is always a Possibility. 
The loyalty of 
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the subordinate ranks inthe army is to their leaders and to the Concept of the army 
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as the determining factor in national] Policy, rather than to the Civilian authorities: 
| 
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therefore, the direction of Military influence can be determineg by very few men. 
| 
In this sense, the army is an element Opposed to Stability rather than one Suarantee. 
: 
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ing stability, 1 has interfereg in the past (most recently in 1945) and may be ex. 
- 
| 
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Pected to do so in the future, if the policies of the civil leaders do not coincide with 
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What the Military Consider to be the true national] interest, 
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Brazilian Policy-makers in looking to the accomplishment Of that Phase of 
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their mission relative to Preservation of territoria] integrity, neeg 8ive serious thought 
| 
Only to threats Posed by Argentina. 
The factors Protecting Brazil trom local attack 
: = 
from any direction except the south (See Section I, pp. 49, 90) woulg operate also 
make Argentine alliance with, for example Peru or the northem 
| More threatening than Argentine power 
comin 
ues between the two countries: the rivalry is not so much over territory or 
Commercia} concessions as jt is over Prestige involved in aspirations to the leadership 
| 
of South America, 
seems reasonable. therefore. that present Ar 
determined by questions of Prestige rather than by aggressiy 
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Lina will not seek to extend her armaments beyond approxima 
| a 
that Argentina 
has no intention of attacking Brazilian terr; 
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In addition, it is doubtfu! Whether Argentina, despite Certain advantages could 
§ 
: 
&Chieve Within the reasonable future sufficient Superiority over Brazil to justify Plans
for attack. 
The Brazilian Army is at present the largest force in South America and 
should be able to maintain a position at least the equivalent of Argentina’s. 
The Brazilian Navy is rated as the equal of the Argentine Navy, though their 
Pe 
strengths are not, strictly speaking, comparable—that of Argentina consisting in capital 
| 
ships and that of Brazil being concentrated in destroyers. 
In addition, the Brazilian 
Navy has many officers and men with valuable operational experience with the US fleet 
| 
_ 
in patrol operations in World War II. 
Brazil is at present superior to Argentina in air power, although it is true 
that the planned rapid expansion in the Argentine air force will, failing similar ex- 
pansion on the part of Brazil, eventually bring the two nations closer to parity. 
At 
present, Brazil has 15 squadrons (179 tactical aircraft) while Argentina has 8 squad- 
rons (187 tactical aircraft) in the air force proper and 6 squadrons (47 tactical air- 
craft) in the naval air arm.. This Argentine numerical superiority, however, is more 
: 
than offset by the tactical superiority of the Brazilian aircraft; the majority of the 
Argentine tactical aircraft were obsolescent before World War II, while the Brazilian 
j 
tactical aircraft are of the same types that were in use by the US Air Force at the 
a 
close of that war. 
Argentina’s financial capacity for additional purchases may be 
# 
| 
greater than Brazil’s. 
The situation, however, will not change immediately, because 
a 
Brazil’s World War II combat aircraft will be worth more tactically than Argentina’s 
* 
Gloster Meteors until Argentina has thoroughly trained pilots and mechanics and 
adequate maintenance facilities for the new planes. 
Brazil now has a total of 1,133 
aircraft of all types, compared with Argentina’s over-all total (including the naval 
air arm) of 905. 
Brazil is also superior in personnel, in a ratio of approximately three 
to one. 
Neither country at the present time has the manufacturing facilities to 
maintain its air force in action. 
Brazilian forces can carry out the third aspect of their cian mission © 
(coastwise-shipping defense and delaying action against invasion) only to a limited 
extent.. The Brazilian Navy is capable, as it was in World War II, of valuable as- 
sistance in patrolling; it does not have the strength to maintain its long coastal- 
shipping lanes free from serious interruption against a major power, even if that 
_ power should be operating at a long distance from its bases. 
Brazilian forces in the, 
Bulge, including forces brought in by air, could contain a strong enemy attack only 
for a short time, and would almost certainly, by their efforts alone, be unable to keep 
the coastal lanes open to their power centers in the south. 
| 
| 
Execution of the fourth aspect of the mission (assistance to Hemisphere forces 
operating in Brazil) lies well within the range of present Brazilian capabilities with 
it 
respect to maintenance of the reasonably adequate World War II bases and staging 
i 
areas already existing in this vicinity. 
Maintenance of local security of the area could 
also be well accomplished by Brazilian forces. 
Any extensive additions to facilities, 
however, such as improvement of interior communications, would nave to be with 
US assistance. 
 Brazil’s capabilities in furnishing expeditionary forces are discussed under 
subsection b. Maximum Capabilities, below. 
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neighbors. 
had to be relaxed in putting together the Brazilian Expeditionary Force even though 
_ 
tributed materially to increasing the combat effectiveness of the Brazilian Army. 
‘Brazilian forces, as at present constituted, have some offensive capabilities. 
The air force, as was pointed out in Section 4, c., p. 65, is much superior to that of any 
- 
neighbor and has limited offensive capabilities over most of South America, though it 
cannot be maintained in action by Brazilian resources. The Brazilian 
Army has 
sufficient superiority over most of its neighbors to indicate on paper great offensive 
capabilities against any of them except Argentina. 
The same factors, however, that 
serve to protect Brazil from the west and north and reduce her defensive problems 
would, of course, increase the difficulty of any offensive operations in these areas. 
It 
is doubtful whether Brazil’s present superiority over Argentina would be great enough 
to promise success in offensive operations, and there is no evidence that Brazil con- 
templates such operations against Argentina, or, for that matter, against any of its 
b. 
Maximum M ilitary Capabilities. 
It is believed that the present Brazilian forces are about as large as the country’s 
economy can stand, since they consume already about one-third of the annual budget. 
Military capabilities can unquestionably be increased by assistance of other powers, 
primarily, of course, by the US. 
The amount of this increase, however, would be far 
less than the numbers of potential Brazilian manpower would indicate. 
US standards 
the entire army was combed for personnel, and this experience is not encouraging for 
the formation of any large force capable of competing on an equal basis with an ex- 
peditionary force of similar size originating from a first-class military power. The 
performance of the Brazilian Expeditionary Force in Italy was mediocre—about the 
equal of the poorest of the US combat divisions. 
The officers showed an ability to 
assimilate training, a reasonable capacity for leadership, and excellent personal military 
qualities; they displayed, however, a lack of aggressiveness that amounted to tactical 
timidity when opposed to German troops, standing in such awe of the German reputa- 
tion that their capacity for assuming the initiative was impaired. 
The Brazilian 
soldiers were adaptable to various terrain and climatic conditions but made an ex- 
tremely poor showing in physical stamina and health; the venereal disease rate was 
exceptionally high, and the total effectives available for a 
this and other 
reasons—were correspondingly low. 
Brazil is cognizant of the poor showing made by the Brazilian iain 
Force in Italy, and has profited by the lessons learned there. 
The Brazilian Army 
has converted completely to US training methods, organization, and doctrine. 
The 
war experience, the training received by many Brazilian officers in US service schools, 
and the work of the Joint Brazil-US Military Commission have been the principal 
factors in this conversion. 
Brazil now has a school system paralleling that of the US, 
adequate school troops, and a system of replacement training centers. 
Two US-equip- 
ped infantry divisions, an armored division, and other miscellaneous troops have con- 
The problem, however, is unfortunately not primarily military, but socio- _ 
logical—that is, it consists not so much in making a better soldier out of the Brazilian 
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citizen, but in making a better Brazilian citizen. 
This task will probably require 
generations at least, since it involves considerable lifting of the economic and social 
level of the population. 
Until this is accomplished, Brazil’s military capabilities, in 
proportion to its population and potential resources, will remain low. 
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STRATEGIC CONSIDERATIONS AFFECTING US SECURITY 
: 
So far as strategic considerations affecting US security are concerned, Brazil must 
be viewed as two distinct areas—a fact which colors many of the political, economic, and 
military elements involved in evaluating Brazil’s strategic importance. 
That part 
of the country including the “Bulge” and the territory north and west of it lies within 
or on the margin of the zone of effective US military predominance. The southern—and 
to Brazilians the most important—part of the country, containing 70 percent of the — 
‘ 
population and most of the major political and economic centers, lies outside the zone 
es 
of effective US milit&ry predominance. Brazil is the only Latin American country so 
_ 
situated as to contain both a strategie area within the zone of US military predomi- 
nance and important centers outside that zone. 
| 
The political significance of Brazil’s peculiar geographic position lies in the fact 
that Brazilian policy is determined in that part of the country lying outside the zone 
of US military predominance. The Brazilian Government, therefore, has a consider- 
able latitude for independent action.* 
In this respect, it is in a situation similar to that 
of the governments of Argentina and Chile, and quite unlike, for example, those of 
Venezuela and Mexico. 
Brazil shares with Argentina—and, to a smaller extent, with 
Chile—capabilities for counter-balancing US strength by collaboration with extra- 
Hemisphere forces, 
or for rallying the more remote countries of the Hemisphere to 
an anti-US cause or program. 
Brazilian policy has tended generally to parallel that of the US in both World 
Wars, and Argentine-Brazilian collaboration in any action unfavorable to the US is a 
rather remote contingency. 
But it would‘not be prudent to rule out completely the 
possibility of such collaboration or of other action that, while not necessarily un- 
friendly, would be adverse to US interests. 
This is demonstrated in previous ABC 
(Argentina-Brazil-Chile) action, and recent Brazilian independent positions on some 
economic matters, such as the Geneva ITO conversations and the question of the de- 
velopment of the oil industry by US capital. 
In the light either of probable continuing 
rivalry between the two large countries or of the much more remote possibility of a 
united anti-US front, the decision as to whether the US should assist either Brazil 
_or Argentina to gain predominance over the other, or should work toward maintaining 
a balance between them, is a most important political strategic consideration. 
Brazil, 
therefore, shares with Argentina the position of greatest political mmportance among 
the Latin countries to US strategic policy. 
Economic considerations of strategic importance to the US include the presence 
of strategic and critical minerals, the availablity of other essential materials not now 
. 
*“The Intelligence Organization of the Department of State does not concur in the above | 
statement. 
We believe that the statement is misleading and that the implication that countries 
lying within the zone of U.S. military predominance do not have considerable latitude for inde- 
pendent action in international affairs is untrue.” 
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critical, and the possibility of a firm and balanced economy contributing to the welfare 
and stability of a probable ally. The economic strength, like the political strength, lies 
principally in the southern part of the country. 
Brazil has relatively large mineral reserves which are of strategic value to the US. 
For example, Brazil is a very important source of piezo electric quartz and tantalite 
which are used in radar equipment, and for thorium and beryllium, used in atomic 
- 
energy research. 
The pressing need for Brazilian materials in World War II, combined 
with the lack of previously planned methods for meeting this need, impelled the US 
to divert to Brazil a great amount of capital, machinery, and technical personnel sorely 
| 
needed elsewhere. 
This experience suggests the desirability of a different method of 
approach for the procurement of strategic minerals in some future emergency. 
The mineral occurrences in Brazil present particular characteristics in that they 
are generally widespread and shallow, are frequently quite limited with respect to 
individual volume, and are often irregular as to volume, shape, and grade. 
Because of 
these fundamental characteristics, the exploitation of the deposits of most minerals 
usually requires a high degré@e of selectivity in mining and generally the adoption of 
surface-mining operations as distinct from underground operations. 
For the same 
reasons, the deposits are seldom adapted to exploitation by methods of mass production 
involving the use of heavy mechanical equipment. 
Therefore, the greatest chance for 
successful procurement seems to lie in programs that begin and continue as long as 
practicable on the simplest possible commercial basis, making maximum use of exist- 
ing producing and marketing channels, strengthened when necessary by financial 
assistance in the form of loans or grants. 
Further assistance through the provision 
of machinery, operating supplies, or technical advice would probably be helpful only 
to a limited degree. 
Price considerations are of primary importance in the stimulation 
of production, which will be achieved only if the price structure is able to stand on 
— 
its own feet without the — resulting from subsidies and tie-ins between 
various products. . 
In addition to the siiidiaie minerals obtained in quantity by the US in World 
War II, Brazil has resources of deep-seated minerals which would be of value to the 
US if their development were well under way before an emergency arose. 
From the 
US point of view, the most important of these are manganese, nickel, and bauxite, of 
which there are substantial reserves. 
However, the outlook for the exploitation of 
these resources (which would require large-scale mining development) is unfavorable 
because: (1) transportation facilities are inadequate; (2) Brazil is badly deficient in 
fuel and power; (3) Brazilian capital and enterprise in general can find profitable 
employment with less risk in industry and therefore are not interested in mining; (4) 
mining legislation and taxation make investment in mining enterprises unattractive 
to foreign capital; and (5) cooperation in large-scale exploitation of Brazilian mineral 
reserves by the US and Brazilian governments has, in the past, left much to be desired 
(See Chapter IT, Section 2. a. (2), Iron, p. 26). 
Because it is well stocked with raw materials, Brazil would seem to have better 
prospects for industrialization, with the possible exceptions of Argentina and Mexico, 
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than any other Latin American country. 
In some respects its industrial structure is — 
well advanced. 
But certainly within the foreseeable future (if ever) Brazil cannot, 
owing to its serious deficiency in coal, achieve any development in the heavy industries 
of sufficient significance to make it a worthy enemy, or an ally from whom the US 
could obtain any important supplies of manufactured war matériel: 
In light industry, 
prospects are more favorable; from present indications, as time goes on, Brazilian in- 
dustry will be able more and more to supply the domestic demand for consumer and 
capital goods of relatively simple manufacture. 
These manufactures will contribute 
to the economic stability of the country, and a stable Brazil is of importance to the US 
whether the latter be at peace or at war. 
Moreover, even this type of industrial de- 
velopment would benefit the US particularly in wartime, should Brazil be either 
neutral or an ally at such time; for it would relieve the US of the necessity of shipping 
(for reasons of high political and military policy) many manufactured goods it can 
ill afford to export in time of crisis. 
Brazil presents two strategic considerations of importance from the military point 
of view: first, Brazil, by size of population, and by historical and present policies of 
cooperation, may be in a position to furnish expeditionary forces or other troops to 
assist US forces in combat or join in a general Hemisphere effort; and, second and more 
important, a portion of Brazilian territory, the Bulge, is the nearest point of the West- 
ern Hemisphere to the Afro-Eurasian land mass. 
| 
_ The capacities of Brazil to furnish an expeditionary or other large military force 
of real value are (see Chapter IV, Section 5. b. 
Maximum Military Capabilities, pp. 69,70) 
_ 
not large. 
In certain situations, however, Brazilian troops might be useful, and their 
participation would at least be a valuable symbol of unity. Therefore, the ability to. 
furnish a force of possibly 50,000 men is of strategic importance to the US, and merits 
inclusion in considerations affecting the drafting of US policy. 
Brazilian territory, as was pointed out at the beginning of this chapter, is so ex- 
- tensive—extending from points easily within the US zone of military predominance 
-. 
to centers of population and industry just as obviously beyond the region over which 
the US can exercise effective control—that it can be thought of strategically as really 
two distinct areas. 
A further peculiarity is that the northern portion, of particular 
_interest to the US because it is the nearest point of the Western Hemisphere to the 
| 
Afro-Eurasian land mass, is so effectively eoratad from the rest of the country as 
— 
to constitute practically an island. 
This “island”—the territory from Recife and Natal to the Guianas—is iatie 
equidistant from Brazilian power-centers at Rio de Janeiro and Sao Paulo, from present 
- 
and possible future US bases in the Caribbean, and from the coast of Africa at Dakar. 
It has practically no land communications with the rest of Brazil or of South America; 
~ 
it is not self-supporting in food supply, and has, with the exception of some textiles 
and sugar refining, no essential industries. 
It can be reached, barring interference, 
- about equally easily from any of the three points mentioned above, and the power 
seizing or holding this territory must expect to be able to meet attacks from at least 
one of the other two directions, from hostile forces whose logistic problems need not 
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be any greater than its own; that is, it would be as easy to supply a force holding the 
Bulge from West Africa (assuming adequate West African land bases had previously 
been developed) as from the Caribbean, and the task of dislodging a hostile force by 
Caribbean-based attack would be little if any easier than by an African-based attack. 
Because of its location and its island characteristics, the strategic importance of 
the Bulge must be considered in two sets of circumstances—its value to an enemy as 
a “stepping-stone” to attack the Panama Canal and the US position in the Caribbean 
generally, and its value to the US as an advance base for offensive or defensive action. 
Since the resources of the Bulge itself are extremely limited, and since an important 
_ 
problem for an attacking enemy would be fuel supply, it may be assumed that this 
enemy attack would strive to reach, as quickly as possible, the Venezuelan oil fields on 
the north coast of South America; thus the enemy’s principal interest in the Bulge would 
be not to occupy it for his own use, but to deny its use to US forces which might in- 
terfere with his cross-Atlantic effort. 
That is, while an enemy probably would not 
_ expend the effort to seize and hold a practically empty Bulge, it would be necessary 
_ 
for him to plan to reduce any strong US forces—which it is assumed would include 
aviation—in the Bulge, before venturing to proceed with an attack on the Caribbean. 
Similarly, while the Bulge may be less important to the US as a possible stepping- 
stone to Africa and Europe than it was during World War II, it does remain important 
for any US trans-Atlantic effort that the Bulge be in friendly hands, to obviate inter- 
ference with such effort. 
But from the US point of view, possibly the greatest import- 
ance of the Bulge is its part in the defensive picture. 
It lies on the flank of the most 
— 
probable line of enemy attack against the Caribbean, and provides an important out- 
post on the circumference of a 3,000-mile-radius defensive circle from the Panama Canal. 
Because of the considerations of the preceding two paragraphs, it seems reason- 
able to attach high military strategic importance to the Brazilian Bulge. 
Adequate 
maintenance of existing facilities (a contribution to Hemisphere defense lying gen- 
erally within the capabilities of Brazil) and joint arrangements both for any neces- 
sary improvements and for the quick transfer of US forces to this territory in case of 
~ eméfgency, would notably increase the strategic security of the US. 
In summary, Brazil is strategically important to the US because: (1) its geographic 
location makes for capabilities for independent action shared only by Argentina and > 
Chile, and thus US Brazilian policy may be said to be central to US Latin American 
policy; (2) Brazil is one of the most important of the Latin countries as a source for 
strategic and critical materials not obtainable elsewhere, and shares with Venezuela, 
Chile, Bolivia, and possibly Cuba, a position as supplier of prime wartime necessities; 
(3) Brazilian territory includes that portion of the Western Hemisphere closest to the 
Afro-Eurasian land mass of vital importance to forces moving north and south in, or 
across, the south Atlantic. 
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APPENDIX A 
* TOPOGRAPHY AND CLIMATE 
Brazil, with an area of 3,286,170 square miles, 90 percent of which lies within 
the tropics, constitutes 45 percent of the continent. 
From north to south the greatest 
distance is 2,670 miles, from east to west 2,690 miles. 
Forests cover about 58 percent 
of this area, and only 3.5 percent of the land is cultivated. 
The meade 
has 3, 642 
miles 
of coastline, most of which is flat and tillable. 
: 
Brazil’s greatest rivers are important not only for transportation, but as a poten- 
) 
tial source of hydroelectric power. 
The country claims 10,000 miles of rivers navi- 
 - gable by large steamers and from 20,000 to 30,000 miles of waterways which are usable 
: 
at least part of the yearby light-draft steamers. 
The Amazon, the world’s largest 
; 
river, is regularly navigated by large ocean-going ships for 1,000 miles and by smaller 
vessels for 2,000. About half of the 200 tributaries of the Amazon also are navigable. 
. 
The rivers which fall from the Central Plateau in a series of rapids and falls offer good 
. 
sites for hydroelectric installations; a large number of these sites are close enough to 
the population centers along the east coast and in the south of Brazil to make their 
q 
- development feasible and desirable. 
Brazil may conveniently be divided into five physical regions: (a) the Amazon 
Lowlands, comprising 770,000 square miles of heavily forested sedimentary plain; 
(b) the Interior Lowlands and Plateau, a roughly triangular area in the central and 
western part of the country which includes the drainage basin of the Parana-Paraguay 
River system as well as the upper reaches of the southern Amazon tributaries; (c) the 
Eastern Plateau; (a) the Coastal Plain; and (e) the Guiana Highlands. 
_ 
‘The Amazon basin comprises one-third of the total area of Brazil. 
It is largely 
uninhabited and unexplored. 
The few people—less than 10 percent of the total popu- 
lation—are mainly concentrated around Sao Luiz in Maranhao and Belém in Para. 
The rest of the basin is sparsely inhabited by Indians. 
Although the forests abound 
in a great variety of products of commercial value such as gums, rubber, nuts, roots, 
cabinet woods and skins of rare animals, they are inefficiently exploited, hence their 
contribution to the Brazilian economy is quite small. 
Rainfall is heavy, and much of 
the forest is so dense as to be described as impenetrable. 
Temperatures seldom exceed 
95° F. because of shielding clouds, but rainfall is heavy throughout, exceeding 80 
inches in the upper Amazon lowlands. 
There is very little temperature variation 
during the year. 
Most of the basin has an elevation of less than 800 feet. 
The Interior Lowlands and Plateau consist of tropical lowland plain and the low 
plateau of Mato Grosso. 
About one-third is forest and the remainder consists of grass- 
land and swampland on which cattle graze. 
The entire area has only 375,000 people 
(about one person per square mile), most of whom make their living from cattle rais- 
ing. 
Rainfall (50-60 inches) is heavy from November through March, while the period 
May through September is characterized by a marked dry season. 
Since the entire 
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region is isolated by the lack of transportation, the area is of little importance to 
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_Brazil’s economy except for its cattle. 
| 
The Eastern Plateau slopes toward the interior fia a steep 1 ,000-mile escarp- 
ment which faces the sea. This plateau is drained by the tributaries of the Amazon 
and the Parana rivers. 
The plateau averages about 2,500 feet in elevation, but its 
mountain ranges rise to 8,000 feet. 
The northern portion of the Eastern Plateau con- 
sists largely of semi-arid savannas. 
The central portion, which contains the three 
richest states, Sao Paulo, Minas Gerais, and most of Rio de Janeiro, has a more equable — 
climate than is found in the north. 
The southern part of the Eastern Plateau with its 
temperate climate has been described as the area best suited for human habitation. 
-Brazil’s “coastal plain” is a clearly defined topographic feature only from the 
Bulge of Brazil southward to Rio de Janeiro. 
In the extreme north the coast of Amapa 
is a wet tropical alluvial lowland which merges with the Amazon floodplain along 
the coast of the state of Paré. 
Continuing eastward, lowland country extends to 
Brazil’s Bulge through the state of Rio Grande do Norte and has few people and 
little produce. 
- 
From Rio Grande do Norte south to Salvador in the cinta of Bahia there is a 
s 
coastal stratified zone of sandstone and shale, the natural cover of which is semi- 
S 
deciduous forest. 
Inland from the coast are hilly uplands. 
In this area the coastal 
s 
strip varies in width from a few miles to over 100 miles, the greatest depth being 
found in northern Bahia. 
In southern Bahia, however, the strip again is narrow 
and southward coastal terraces alternate with coastal lowlands of varying widths. 
Where the rivers Paraiba and Doce come to the sea the strip breaks inland to 
include the alluvial river valley bottoms. 
Inland from the coastal strip are crystalline 
4 7 
hilly uplands, tabular uplands or—as is the case at Rio de Janeiro—low mountains, 
sz | 
known as the Great Escarpment. 
Southward from southern Bahia the Great Escarp- 
, 
ment follows the coast for over 1,000 miles. Between Rio de Janeiro and Tubarao in 
Santa Catarina much of it comes to the water’s edge and here the coastal strip dis- 
appears completely in many places. 
From Santos in Sao Paulo the strip is narrow to 
) 
Sao Francisco do Sul in Parana; it becomes wider at the mouth of the Rio Negro, only 
* 
to narrow again as the Serra do Mar comes close to the shore near Floriandépolis in the 
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state of Santa Catarina. From this point southward the coastal strip is a narrow 
| 
zone of lowland which widens abruptly and merges into the lowlands and prairie 
country of southern Rio Grande do Sul. 
The Guiana Highlands in northern Brazil are for the most part forested, but part 
of their slopes consists of savannas. 
Deeply incised valleys have broken most of the 
region into a confusion of features. 
This area drains into the Amazon basin, but the 
rivers are shorter than other tributaries of the Amazon because the land north of the 
river rises rapidly to the Guiana highlands and the continental divide. 
In general, 
altitudes vary from 600 feet in the south to about 4,000 feet in the north. 
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There is an almost religious obligation to take care of relatives, retainers, Servants, as 
| 
well as friends, which accounts for the unblushing nepotism found in Brazil. 
vi 
f a degree 
not approximated in the US except possibly among Texans. 
APPENDIX C 
POPULATION CHARACTERISTICS AND STATISTICS 
The Brazilian population is a mixture of diverse races, the miscegenation of which 
has been greatly facilitated by a traditional lack of race prejudice in the country. 
Indian, Negro, and various European and Near Eastern strains are intermingled. 
Official statistics on the racial composition of the population are unavailable because 
the law forbids distinction of race or color in the census. 
The most conspicuous of 
the important areas, ethnically speaking, are: the Amazon Valley, which is largely 
Indian; the central coast from Pernambuco to Bahia, the population of which fs esti- 
| 
mated to be more than 60 percent negroid; the high plateau area in the northeast 
part of the country, inhabited~by a mixture of white and Indian; and the southern 
States, about three-fourths white. 
| 
A salient feature of Brazilian society is the absence of a large middle class. 
The 
upper class is determined by family, professional standing, and to some extent by 
wealth. The remnant of the imperial aristocracy in Rio de Janeiro maintains an 
exclusive circle. 
The nouveau riche are primarily concentrated in the state of Sao Paulo. 
Another characteristic of Brazilian life, in any class, is the intense family feeling. 
Typical Brazilians vary from one region to another more than the people of the US. 
There is a strong local patriotism or sense of belonging to a regional group of 
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1. 
POPULATION By STATES (1940 CENsuUs). 
| 
DENSITY PER 
STATE 
POPULATION 
SQ. KM. 
a 
BRAZIL 
. 
41,565,083 
| 
4.9 
| 
Alagoas 
957,628 
33.5 
Amazonas 
453,233 
0.3 
Bahia 
3,938,909 
1.4 
Ceara 
2,101,325 
14.1 
Federal District 
1,781,567 
1,526.6 
Espirito Santo 
758,535 
17.7 
Goias 
832,869 
1.3 
Maranhao 
1,242,721 
3.6 
Mato Grosso 
434,265 
0.3 
Minas Gerais 
6,798,647 
11.6 
Para 
956,870 
Paraiba 
1,432,618 
25.6 
Parana 
1,248,536 
6.3 
Pernambuco 
2,694,616 
27.2 
Piaui 
826,320 
3.4 
Rio de Janeiro 
1,862,900 
43.9 
Grande do Norte 
174,464 
14.8 
Rio Grande do Sul 
8,350,120 
12.3 
| 
Santa Catarina 
1,184,838 
12.5 
Sao Paulo 
7,239,711 
29.3 
| 
Sergipe 
545,962 
25.3 
2. SIGNIFICANTLY LARGE ALIEN Groups (1940 CENSUS). 
NATIONALITY 
NUMBER 
Portuguese 
354,311 
Spanish 
| 
147,897 
TOTAL 
1,282,833 
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APPENDIX D 
BIOGRAPHICAL DATA 
1. EURICO GASPAR DUTRA. 
Age 63. 
General Dutra, a native of Mato Grosso, was elected to the presidency of 
Brazil in December 1945. 
| 
While Dutra’s shrewdness should not be discounted, he seems to have made his way 
largely by dint of hard work and stubborn perseverence. 
He entered the army in 
1902 as a student in a military preparatory school in Rio Grande do Sul, and went from 
there to the national military academy. 
Although the record is obscure, he seems to 
have been expelled from the academy and obliged to finish his studies elsewhere. 
He 
was commissioned a second lieutenant in 1910. 
- Throughout the early twenties, when younger army officers such as Eduardo Gomes, 
Luiz Carlos Prestes, and Canrobert Pereira da Costa, were active in armed revolts 
against the Bernardes administration, Dutra was unswervingly loyal to the govern- 
ment. 
Moreover he took no part in the Vargas revolution (1930) and, as a penalty 
for failing to support the winning side, he was assigned to one of the worst posts in 
the country, on the Paraguayan border. 
Fortunately, his commanding officer, General 
Bertoldo Klinger, befriended Dutra and placed him on his staff. 
When the Sao Paulo 
Revolution broke out in 1932, Dutra was as usual on the side of the government. 
His 
- regiment marched into Sao Paulo under Goes Monteiro. 
Dutra’s conduct in this 
| 
compaign restored him to favor and he was made a brigadier general and placed in 
command of the Second Infantry Brigade in Rio. 
From 1936 to 1945 Dutra served as Vargas’ Minister of War where he acquired 
a reputation as a man of determination and integrity. 
Nevertheless, he was for some 
time regarded as a figurehead for Goes Monteiro. 
In 1940, Vargas began to give 
Dutra more and more responsibility in order to build him up as a counterweight to 
Gées Monteiro’s political influence and power. 
The removal of Gées as Chief of Staff 
in 1943 placed Dutra in a very strong position. 
- When Dutra was selected as the PSD’s aiiiiiainas candidate in 1945 it was 
erroneously assumed that he would be a Vargas puppet. 
The part that Dutra played 
in the coup of 29 October 1945, which forced Vargas to resign, clearly belied the earlier 
misconception of Dutra’s dependence upon the former dictator. 
-Dutra’s present relations with General Gées Monteiro and the relative a. 
of each with the army are open questions. 
There were unconfirmed rumors last year 
that the two were on very bad terms and that Dutra had lost prestige with the army. 
An August 1948 report, however, states that the two generals are good friends. 
While 
Gées is obviously a “strong man” and does much to foster this impression, it is well to 
remember that Dutra, during his long service as War Minister, was able to _— many 
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2. 
OSWALDO ARANHA. 
Age 54. Aranha, a native of Rio Grande do Sul, attended the Military Academy 
in Rio and the Ecole des Hautes Etudes Sociales in Paris. 
He also has a degree from 
the Law Faculty of Rio de Janeiro. 
After graduation from the latter institution, 
Aranha returned to his native. state to practice law and enter politics. 
He held 
various state offices and also participated in the suppression of two local rebellions. 
| 
Aranha’s association with Vargas began in 1929 when he accepted a post from 
Vargas in the state government. Aranha took a leading part in the revolution of 
| 
1930, and was.a close associate of Vargas throughout most of the latter’s presidency. 
He served successively as Minister of Justice, Finance Minister, Ambassador to Wash- 
ington (1934-1938), and Foreign Minister (1938-1944). 
To Aranha goes much of the 
credit for the policy of Western Hemisphere solidarity that Brazil enunciated before 
Pearl Harbor. 
During the time that the Brazilian Army was conspicuously pro- 
German and that Vargas himself appeared to have a strong Axis orientation, Aranha 
was unfailing in his cordiality toward the US and in the expression of his desire that 
the two countries work together. 
Aranha resigned from the Cabinet in 1944 and the following year he supported 
the presidential candidacy of Eduardo Gomes. 
In 1947, Aranha was named to succeed Leao Velloso as head of the Brazilian 
UN 
| 
delegation and Brazilian representative on the Security Council. 
He was elected Presi- 
dent of the UN General Assembly at its special session in April of 1947 and again at the 
regular session in September. 
| 
Many Brazilians feel that Oswaldo Aranha is their foremost citizen internationally. 
His charm and open manner have won friends throughout the world. 
He is generally 
regarded as the best friend of the US in Brazil. 
However, it must be kept in mind that 
Aranha is an ambitious man and a none too scrupulous one where personal fortunes 
are at stake. 
3. ADHEMAR PEREIRA.DE.BARROS. 
Age 47. ‘Barros is Governor of Sao Paulo, the richest state in Brazil. 
He is the 
son of a Santos coffee exporter. 
Barros is a man of great energy whose crowning 
ambition is to win the presidential election in 1950. 
He is extremely resourceful in his 
efforts to appear to be all things to all men at all times. 
From 1934 to 1937, Barros was a deputy in the Sao Paulo state legislature. 
In 
1936 there was some evidence that he was a member of a Communist underground 
organization in Sao Paulo. 
However, in 1938 Vargas selected him as Federal Inter- 
ventor for Sao Paulo, an appointment causing general astonishment throughout the 
State. 
Barros was in desperate financial straits at the time of this appointment. 
When he left the interventorship he was a rich man and reportedly the owner of a 
textile mill, a chocolate factory. a distillery, and other properties. 
His former Sec- 
_ 
retary of Finance charged that he had misappropriated public funds. 
These charges 
and the supporting evidence were filed away by Getulio Vargas for future use. 
Attempts 
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have since been made to press the charges, but now that Barros is governor, the courts 
are likely to avoid 
4. PEDRO AURELIO DE GOES MONTEIRO. 
Age 59. 
Gées Monteiro, the ranking general in the Brazilian Army, is one of the 
most powerful figures in national politics. 
He comes from a military family in Alagoas 
which rules that state with an autocratic hand. 
Two of his brothers, Edgard and 
Ismar, were federal interventors under Vargas. 
A third, Silvestre Pericles, is now 
governor. 
Pedro Aurelio and Ismar are PSD senators from Alagoas. 
Silvestre has 
lately joined the PST, which also supports President Dutra. 
, Pedro Aurelio was born in Sao Luiz de Quitunde, Alagoas, in 1889. 
At 15 he 
enlisted in the Army and served six years as a private before entering the Military 
Academy. In 1914 he was commissioned a second lieutenant. 
His career received its 
greatest impetus in 1930 when he took command of Vargas’ successful rebel forces 
in Rio Grande do Sul. 
In ‘1931 he was promoted in quick succession to colonel and 
brigadier general. 
The Sao Paulo Revolution broke out the following year. 
As Com- 
mander in Chief of the Federal forces, Gées crushed the rebellion in less than three 
months, and was immediately promoted to major general. 
Between 1933 and 1943 
he was successively Commander of the First Group of Military Regions, Minister of 
War, Commander of the First and Second Group of Military Regions, and Chief of Staff 
of the Army. 
In 1943 Gées was relieved as Chief of Staff and sent to Montevideo as Brazilian 
delegate to the Emergency Committee on Political Defense. 
His initial reluctance to 
cooperate with the Allies in the war as well as his political power in Brazil probably 
caused Vargas to take this action. 
In November 1944 he returned to Brazil on leave 
and began agitating for direct general elections and freedom of the press. 
When 
Dutra resigned from the War Ministry to run for President, Gées was appointed to 
succeed him. 
He announced that the armed forces would guarantee the elections 
and on 29 October 1945 led the coup that deposed Vargas. 
President Dutra made Gées Monteiro Minister of War in 1946, but because of 
his poor health he later resigned in favor of his assistant and protégé, General Canro- 
_ bert. 
Gé6es returned to his former post in Montevideo. 
While there he was elected 
senator from Alagoas. 
Now a whole-hearted advocate of cooperation with the US, Gées Monteiro was a 
member of the Brazilian delegation to the Rio Conference in 1947. 
He used to be bit- 
terly anti-Argentine, but his growing fear of the USSR has tempered his attitude toward 
Argentina. 
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1789-1792 
1808 
1821 
1822 
1831 
1831-1840 
1840-1889 
1865-1870 
1888 
1889 
1891 
1891-1894 
1894-1898 
1898-1902 
1902-1906 
1906-1909 
1909-1910 
1910-1914 
1914-1918 
1917 
1918 
1918-1919 
1919-1922 
1922 
1922-1926 
1924-1925 
1926-1930 
1930 (Mar. ) 
1980 (Oct.) 
1930 (Nov.) 
1930-1945 
1932 
APPENDIX E 
CHRONOLOGY 
Discovery of Brazil by the Portuguese navigator Pedro Alvares Cabral. 
Minas Gerais Conspiracy, an unsuccessful independence movement. 
Transfer of the Portuguese court to Rio de Janeiro. 
Return of King Joao VI to Portugal. 
Declaration of independence; Dom Pedro proclaimed Constitutional 
Emperor of Brazil. 
Abdication of Pedro I in favor of his son. 
Regency of J osé Bonifacio de Andrada. 
Reign of Pedro II as Constitutional Emperor of Brazil. 
Paraguayan War. 
Emancipation of the slaves. 
Proclamation of the Republic. 
Enactment of the Republican Constitution drafted by Ruy Barbosa; 
presidency and forced resignation of Marshal Deodoro da Fonseca. 
Presidency of Marshal Floriano Peixoto. 
Presidency of Prudente de Morais (of Sao Paulo). 
Presidency of Campos Salles (of Sao Paulo). 
Presidency of Rodrigues Alves (of Sao Paulo). 
Presidency of Affonso Pena (of Minas Gerais). 
Presidency of Nilo Pecanha. 
Presidency of Marshal Hermes da Fonseca (of Rio Grande do Sul). 
Presidency of Wenceslau Braz (of Minas Gerais). 
Brazil enters World War I on side of Allies. 
Re-election of Rodrigues Alves (of Sao Paulo) who died before assuming 
presidency. 
Interim presidency of Delfim Moreira (of Minas Gerais). 
Presidency of Epitacio Pessoa (of Paraiba). 
Military revolt following election of Artur Bernardes. 
Presidency of Artur Bernardes (of Minas Gerais). 
Military rebellion centering in Sao Paulo. 
Presidency of Washington Luiz (of Sao Paulo). 
| 
Getulio Vargas_(of Rio Grande do Sul) defeated in presidential election 
by Julio Prestes de Albuquerque (of Sao Paulo). 
Revolution led by Getulio Vargas. 
Abrogation of Constitution of 1891, Vargas assumes dictatorial powers. 
Presidency of Getulio Vargas. 
Sao Paulo Revolt. 
PRESTy 
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1934 
1935. 
1937 (Oct.) 
1937 (Nov.) 
1937 (Dec.) 
1938 (May) 
1942 (Aug.) 
1945 (May) 
1945 (Oct.) 
1945 (Oct.)- 
1946 (Jan.) 
1945 (Dec.) 
1947 (May) 
1947 (Oct.) 
1948 (Jan.) © 
- Enactment of new Constitution by Vargas-picked Constituent Assembly; 
election of Vargas by Assembly for four-year term as President; 
transformation of Assembly into Congress. 
Abortive revolt of Communist-led National Liberation Alliance. 
Congressional authorization for the: establishment of martial law and 
press censorship. , 
Vargas coup; cancellation of scheduled elections; dissolution of Con- 
gress; proclamation of new Constitution legalizing ny by 
Vargas for indefinite period. 
: 
Decree outlawing the Integralistas. 
Unsuccessful putsch by Integralistas. 
Brazil enters World War II on side of Allies. 
New electoral decree and granting of political amnesty. 
Army coup ousting Vargas. 
Interim presidency of Chief Justice José Linhares. 
Election of General Eurico Gaspar Dutra. 
_ 
Decision of Superior Electoral Tribunal outlawing Communist Party. 
Break of relations with USSR. 
: 
Passage of law nee mandates of Communist Party office- 
holders. 
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NATIONAL INTELLIGENCE SURVEY 
BRAZIL - I 
SOUTHEAST BRAZIL 
SECTION 23 
WEATHER AND CLIMATE 
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AIR FoRCE 
OCTOBER 1954 
NIS 
TABLE OF CONTENTS FOR SECTION 23 
A. General weather and climatic conditions 
B 
C 
D 
E 
| 
1. Introduction 
. 
2. Synoptic aspects of the climate 
1. Organization . 
a. General circulation 
b. Air masses. 
Air operations 
. Cloudiness 
Upper winds 
. 
(1) Winter 
(2) Summer 
. 
Urper-air temperatures 
. 
arbulence 
.. 
-ground operations 
. 
Ceiling 
. 
Ability 
Low-level turbulence 
. 
. Ground surface operations 
a. Precipitation 
. 
b. Temperature . 
c. Relative humidity 
. 
d. Surface winds 
e. Overall 
effect of surface weather 
on 
__ Storage, and shelter 
(1) Clothing. 
(2) Storage 
. 
(3) Shelter 
Amphibious operations 
. 
a. North of Natal 
. 
b. Natal south to 20°S. 
c. South of 20°S. 
2. Operation 
. 
. Climatic data tables 
. 
. Weather and military operations . 
. Comments on principal sources 
. 
. Meteorological facilities and organization 
Conient 
per 
OC2 OG 
date __18 0CT 
PAGE 23-i 
Page 
23- 7 
23-15 
4. 
23-15 
|
LIST OF FIGURES 
Page 
Fig. 23-1. 
Map 
Circulation pattern, July 
23- 2 
Fig. 23-2 
Map 
Circulation pattern, January 
23- 2 
Fig. 23-3 
Map 
Mean monthly precipitation 
23- 6 
Fig. 23-4 
Map 
Mean daily maximum and minimum tem- 
23- 8 
: 
| 
peratures 
Fig. 23-5 
Map 
Absolute maximum and minimum temper- 
23- 9 
atures 
| 
Fig. 23-6 
Map 
Surface wind roses, January 
23 - 10 
Fig. 23-7 
Map 
Surface wind roses, April 
23 - 11 
Fig. 23-8 
Map 
Surface wind roses, July 
23-12 
Fig. 23-9 
Map 
Surface wind roses, October 
23 - 13 
Fig. 23-10 
Table 
Clothing ~_requirements 
23 - 14 
Fig. 23-11 
Table 
Mean cloudiness 
23-17 
Fig. 23-12 
Table 
Mean number of clear days 
23 - 18 
Fig. 23-13 
Table 
Days with thunderstorms 
— 
23 - 18 
Fig. 23-14 
Table 
§ Average winds at specified altitudes 
23 - 19 
Fig. 23-15 
Table 
Mean temperature at specified altitudes 
23 - 19 
Fig. 23-16 
Table 
Frequency of specified ceilings and visibilities 
23 - 19 
Fig. 23-17 
Table 
Days with ceilings <1,000 feet 
| 
23 - 20 
Fig. 23-18 
Table 
Days with visibility <1 mile 
23 - 20 
Fig. 23-19 
Table 
Frequency of specified visibilities at 0900 LST 
23-20 
‘Fig. 23-20. 
Table 
Mean precipitation 
23 - 21 
Fig. 23-21 
Table 
Maximum 24-hour precipitation 
23 - 22 
Fig. 23-22 
Table 
Days with precipitation =0.01 inch 
| 
23 - 23 
Fig. 23-23 
Table 
Mean daily temperature 
23 - 24 
Fig. 23-24 
Table 
Mean daily maximum and minimum temper- 
23 - 25 
atures 
Fig. 23-25 
Table 
Absolute maximum and minimum temper- 
23 - 27 
| 
atures 
| 
Fig. 23-26 
Table 
Mean daily relative humidity 
23 - 29 
Fig. 23-27 
Table 
§ Mean daily surface wind velocity 
23 - 29 
Fig. 23-28 
Table 
Prevailing direction of surface wind 
23 - 30 
Fig. 23-29 
Map 
Station locations 
follows 23 -31 ~. 
This Section was prepared for the NIS under the general 
supervision of the Directorate of Intelligence, USAF, by the 
Air Force/Air Weather Service in coordination with the Joint 
— 
Meteorological Committee. 
Material on amphibious opera- 
tions was prepared by the Office of Naval Intelligence and 
material on clothing, storage, and temporary shelter by the 
Office of the Quartermaster General. 
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-
FORCE — OCTOBER 1954 
coastline. 
regions. 
The northern region, roughly one-third 
MILITARY GEOGRAPHY 
23. 
Weather and Climate 
A. General weather and climatic conditions 
1. Introduction 
The climate of the NIS 94-I Area, which extends 
from the Equator to 33°S., is generally tropical in 
nature. Periods of heavy rain, consistently high 
temperatures and relative humidities, and light 
surface winds are characteristic. 
| 
| 
Of sixteen separate states located within South- 
east Brazil, 15 share portions of:the 3,500-mile 
The Area can be divided into three 
of the Area, is composed of coastal lowlands which 
seldom reach elevations of more than 500 feet. 
The central and southern regions, though similar 
to each other in terrain, are distinguished by cer- 
tain climatic differences. 
These regions consist of 
a high plateau averaging 3,000 feet in elevation 
and containing a few mountain peak: over 6,000 
feet high. 
The highest mountain peak, Pico da 
Bandeira, is 9,462 feet and is located 175 miles 
northeast of Rio de Janeiro. 
its maximum elevation in the interior of the cen- 
tral region, sloping gently toward the coast in the 
north and toward the Rio Parana and Rio Para- 
quai in the west and south. 
The eastern edge of 
the plateau is a well-defined escarpment 
(The 
Great Escarpment) which extends from approxi- 
mately 30°S. to 12°S. 
North of 12°S. the coastal 
plain rises gently toward the inland plateau. 
The 
small climatic variations in this Area are due 
primarily to the differences in elevation. 
Typhoon or hurricane seasons typical of other 
tropical climates are nonexistent in this portion of 
the world. These violent storms breed in every 
tropical ocean in the world except the South Atlan- 
tic, an interesting meteorological fact and an im- 
portant practical advantage for the coastal areas 
of Southeast Brazil. 
Snow occurs infrequently in 
the Area; its occurrence is limited to the higher 
elevations in the extreme southern portion of the 
territory. 
Note 
Requests for solutions to specific problems in- 
volving the interpretation of the weather factor 
in the user’s unique operational terms should be 
directed to the Commander, Air Weather Service, 
MATS, USAF, Washington 25, D. C. 
The plateau reaches 
© 
2. Synoptic aspects of the climate 
a. GENERAL CIRCULATION — The climate of this 
Area is controlled 
primarily by the Southern 
Hemisphere trade winds, which originate in the 
South Atlantic anticyclone 
(FIGURES 23-1 and 
23-2). 
The 
center 
of this high-pressure 
cell 
changes geographical position in different seasons 
of the year. 
The change of position effects a 
change in the airflow over Southeast Brazil. 
In 
winter (June, July, August), for example, when 
the center of the cell is relatively close to the coast, 
- southeasterly winds are common to the northern 
portion of the Area and north to northeasterly 
winds predominate over the south. 
In summer 
(December, January, February), on the other hand, 
the center is farther out to sea, and the trade winds 
assume an easterly direction over the northern and 
central portions of the Area and a northeasterly 
direction over the southern portion. 
During the winter season the South Atlantic 
high moves to the north; consequently, the trade 
winds over the southern portion of the Area lose 
their intensity and are interrupted by migratory 
low-pressure cells moving north from the polar 
regions. 
These lows bring changing weather to 
the Area. 
In the height of the winter season a 
cold outbreak from the south may be expected 
once every 6 days. 
These storms (called friagems) 
and their associated fronts bring cooler tempera- 
tures, rain, and considerable cloudiness to south- 
ern Brazil. 
Although these storms normally re- 
main south of the 20th parallel, an unusually 
strong outbreak may advance as far north as the 
Equator. 
This is the only place in the world where 
such a phenomenon has been observed. 
Such an 
occurrence is rare even in Southeast Brazil; but 
occasionally the temperature may drop 5 to 6 
Fahrenheit degrees, and when it does the natives 
| 
shiver and are liable to catch colds because of 
this slight drop from the normal. 
_ 
For the greater portion of the Area the climate 
is essentially tropical in nature. 
The weather 
varies little from season to season; changes that 
do occur are slow and gradual. 
Regional and 
seasonal variations in climate are functions of local 
terrain rather than of changes in the circulation 
pattern. 
PaGE 23-1 
} 
| 
| | 
&
STREAMLINES 
-~5--- 
WIND SPEED IN MPH. 
SOUTH ATLANTIC 
HIGH-PRESSURE CELL 
FIGURE 23—1. CIRCULATION PATTERN, JULY 
STREAMLINES 
J 
oe §e-- 
wind SPEEDO IN MPH. 
SOUTH ATLANTIC 
HIGH-PRESSURE CELL 
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FIGURE 23-2. CIRCULATION PATTERN, JANUARY 
PAGE 23-2 
b. AIR MASSES — Three air masses are common 
in this NIS Geographic Area: equatorial, tropical 
maritime, and polar maritime. 
Equatorial air is 
found over the northern portion of the Area dur- 
ing the summer months. 
This air mass originates 
near the Equator and is carried over northeastern 
Brazil by the trade winds. 
Cumulus clouds build- 
ing up to afternoon thunderstorms, excellent visi- 
bilities except in rain showers, occasional early 
morning fog, consistently high temperatures, high 
relative humidities, and instability are character- 
istic of this air mass. 
Tropical maritime air is prevalent over this en- 
tire Area except in the north in summer and in 
> 
the south in winter. 
It originates in the South 
Atlantic anticyclone and, like equatorial air, is 
transported to the Brazilian coast by the trade 
winds. 
Subsidence within the source region re- 
duces the moisture content of the air and causes 
the principal 
difference 
between 
tropical 
and 
equatorial air—the almost complete absence of 
thunderstorm activity in tropical air. 
Although 
heavy rain seldom occurs over locations dominated 
by this air mass, the air contains enough moisture 
to follow the cloud pattern established by equa- 
torial 
air. 
The afternoon 
cloud maximum 
is 
apparent as swelling cumulus rather than cumu- 
lonimbus, and light rain showers rather than 
thunderstorms 
result. 
Other 
weather 
features 
characteristic of equatorial air are inherent in 
tropical air. 
| 
| 
Polar maritime air originates in the polar re- 
gions of the south and is carried uver the southern 
portion of this Area by migratory storm centers, 
especially during the winter season. 
Cool tem- 
peratures, fair weather, and excellent visibilities 
prevail in this air mass when the effects of frontal 
weather have passed. 
The leading edge of this air 
mass is marked by an active cold front, generating 
thunderstorms, precipitation, and extensive cloudi- 
ness in the frontal zone. 
The duration and inten- 
sity of frontal weather 
is dependent upon the 
strength of the outbreak and, to a lesser extent, the 
season of the year. 
Polar maritime air seldom 
exists as such for any length of time; it is quickly 
modified and loses its identity to the predominant 
tropical air mass of the north. 
B. 
Weather and military operations 
This Subsection is concerned with the effects of 
various meteorological elements and their varia- 
tions upon military operations, which are sub- 
divided into four groups: air, air-ground, ground 
surface, and amphibious. 
Included 
in each of 
these groups is a wide variety of specific operations. 
The discussion which follows is not, for the most 
part, broken down by specific operations, but by 
the meteorological elements as they affect each 
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AIR FORCE - OCTOBER 1954 
group as a whole. 
Climatic elements are discussed 
individually under the type of operation for which 
they appear to be of primary importance. 
1. Air operations 
a. CLoUDINESS 
— The annual average cloudi- 
ness over the entire NIS 94-I Area is between 5- 
and 7-tenths, although the cloudiness within spe- 
cific regions may vary considerably from these 
means. 
The maximum of coastal cloudiness is 
found near 16°S., where the 7-tenths annual aver- 
age is normal throughout most of the year; the 
- 
minimum of 5-tenths 
is common 
in the Natal 
region in the north and the Rio Grande region in 
the south. 
The largest seasonal range of cloudi- 
ness is generally found in the areas of minimum 
annual cloudiness, where a range from 7-tenths 
cloudiness in summer 
to 3-tenths cloudiness in 
winter exists. 
Of interest is the fact that the 
season 
of maximum 
cloudiness 
is winter 
near 
Natal, while spring has the high cloud average at 
Rio de Janeiro. 
Figures 23-11 and 23-12 give 
tabular information on cloudiness. 
| 
Clouds are predominantly cumuliform in nature 
over Southeast Brazil, though stratus-type clouds 
do occur with winter frontal conditions and along 
portions of the coast during all seasons. 
Bases of 
the prevailing cumuliform clouds are normally 
about 4,000 feet. lowering to 2,000 feet in precipi- 
tation; cloud tops extend to 15,000 feet during the 
afternoon hours at the peak of their development. 
The cumuliform clouds grow to large swelling 
cloud masses but seldom mature to the thunder- 
storm stage. 
Aircraft will generally encounter heavy turbu- 
lence in these cumulus clouds; heavy icing at 
upper-air temperatures below 0° C. is also possible. 
Flight around rather than through these clouds is 
advisable and easy to accomplish since cloud cover 
is seldom overcast. 
The conical nature of cumulus 
clouds 
makes 
circumnavigation 
easier 
at the 
higher altitudes. 
Thunderstorms, 
while 
more 
infrequent 
than 
cloud conditions indicate, can be violent in this 
portion of the world. 
At times cumulonimbus 
clouds push up as high as 50,000 feet, breeding 
Note 
Air operations are defined as those taking place 
above the frictional influence of the terrain on 
atmospheric circulation. 
Some of the specific 
operations which can be included in this cate- 
gory 
are: 
high-level 
visual 
bombing, 
radar 
bombing,. aerial reconnaissance, and fighter sup- 
port and interception. 
In most cases these op- 
erations are concerned primarily with upper-air 
meteorological phenomena such 
as cloudiness 
and aircraft icing: but in some instances, surface 
meteorological conditions can become extremely 
important. 
Detailed descriptions of surface con- 
ditions may be found in the Subsections on Air- 
ground and Ground Surface Operations. 
MILITARY 
GEOGRAPHY 
violent turbulence, excessive lightning, heavy rain, 
and possibly heavy hail. 
The danger of heavy ice 
accretion is present at altitudes above the freezing 
level. 
Flight through 
these storms 
should 
be 
avoided if possible. 
The mean number of days 
with thunderstorms is given tabularly in FIGURE 
23-13. 
| 
b. UPPER WINDS — Winds above 15,000 feet are 
more consistent in speed*and direction than winds 
at lower levels. 
The steady character of these 
winds is best presented in tabular form. 
FIGURE 
| 
23-14 shows the seasonal mean winds at altitudes 
above 15,000 feet over this Area. 
The following 
discussion pertains to winds up to altitudes of 
15,000 feet. 
Winds in this stratum of the atmos- 
phere show variation in direction and speed rela- 
tive to season and geographical location. 
(1) Winter— During 
the 
winter 
season 
(June, July, August), upper-air winds over South- 
east Brazil are predominantly easterly from 10°S. 
to the northern coastline. 
They are of sufficient 
strength to penetrate inland to the western bound- 
ary of the Area and dominate the entire. northern 
portion. 
The easterly winds continue their domi- 
nance between 10° and 20°S., but their vertical 
extent and inland penetration is less than over the 
more northerly portion of the Area. 
Vertically 
they predominate to 8,000 feet, and inland regions 
show considerable variation in direction. 
South .of 20°S. the prevailing direction swings 
- around to the north and extends up to 15,000 feet; 
— 
farther south at the boundary of the Area the 
northerly winds extend to 5,000 feet. 
The pre- 
vailing westerlies of the Southern Hemisphere are 
found above this wedge-shaped layer of northerly 
winds. 
Wind speeds in all zones seldom reach 41 
knots; they are usually in the 15- to 28-knot range. 
(2) Summer—The 
summer 
season 
(De- 
cember, January, February) is marked by a weak- 
ened circulation pattern, a consequent reduction 
in wind speeds, and more variation in wind direc- 
tion. 
North of 10°S. the prevailing direction be- 
comes northeasterly. 
Between 10° and 20°S. the 
prevailing 
direction 
remains 
easterly 
but with 
considerably more variation 
in direction, while 
south of 20°S. a prevailing northeasterly direction 
is normal. 
Summer wind speeds seldom exceed 
30 knots and are usually in the 10- to 20-knot 
range. 
C. UPPER-AIR TEMPERATURES — FIGURE 
23-15 
shows the mean upper-air temperatures for speci- 
fied altitudes and months at stations in the Area. 
Of significance is the rapid drop in temperature 
over the southern region during the winter season. 
The effect of the intrusion of cold air from the 
south is particularly evident in these upper-air 
data for levels below 30,000 feet. 
Also evident is 
PaGE 23-3 
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= 
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the fact that the freezing level is most often found 
above 10,000 feet over the major portion of the 
Area. 
As previously mentioned, 
aircraft 
icing 
problems are only of concern above 10,000 feet in 
the cumuliform clouds. 
The values given in Fic- 
URE 23-15 are average values; individual situations 
may show wide variation from the average. 
While 
averages are adaptable to general planning, they 
are of little value to a specific operation. 
d. TURBULENCE — Turbulence 
in 
Southeast 
Brazil is experienced in thunderstorms and cumu- 
liform clouds and in air heated by the earth’s sur- 
face. 
Although the turbulence created by cumu- 
lus and cumulonimbus clouds is the more danger- 
ous, it is more easily avoided. 
The turbulence 
caused by the heat of the sun being reflected from 
the earth’s surface is annoying but not dangerous. 
This type of turbulence, common to all tropical 
climates, reaches 
a maximum in the afternoon and 
becomes insignificant at night. 
Such turbulence is 
not necessarily marked by cloudiness and may be 
encountered in clear air. 
The lush vegetation of 
the Brazilian jungle has a damping effect on this 
phenomenon; over rocky or barren areas its effect 
may be noticeable at altitudes as high as 10,000 
feet, although it is more evident in the lower 
0,000 feet of the atmosphere. 
2. Air-ground operations 
a. CEILING — In Southeast 
Brazil, 
ceilings 
within the frictional layer, the lower 2,000 feet of 
the atmosphere, vary significantly with the season 
and the region. 
North of 10°S., ceilings less than 
2,000 feet occur infrequently. 
Fortaleza has an 
annual average of 2 days per year with ceilings 
2,000 feet or lower. 
This order of magnitude holds 
true for all of this portion of Brazil. 
The fre- 
quency of such ceilings increases steadily toward 
the south; typical figures show 15 days at Salvador, 
66 days at Rio de Janeiro, and 100 days at Pérto 
Alegre. 
As the number of days with ceilings 2,000 
feet or less increases, a seasonal maximum becomes 
Note 
Air-ground operations are defined as those tak- 
ing place in, or primarily influenced 
by, the 
meteorological conditions within the frictional 
layer 
above 
the 
earth’s 
surface. 
Operations 
such as tactical support, low-level reconnais- 
sance, parachute drops, chemical and biological 
warfare, and incendiary bombing are included 
within this definition. 
Although many of these 
operations may originate above the frictional 
layer, their success or failure would, to a large 
degree, depend upon the conditions at or near 
the 
surface. 
For 
example, 
aircraft 
carrying 
chemical agents might fly at a high altitude, but 
surface wind, surface temperature, and stability 
of the lower layers would determine the degree 
to which the contaminant could be dispersed. 
A description of surface conditions may be found 
in the Subsection on Ground Surface Opera- 
tions. 
PaGE 23-4 
evident. 
June, July, and August furnish most of 
these ceilings at Salvador; the same months record 
a maximum at Rio de Janeiro, while at Florianopo- 
lis the maximum occurs during September, Octo- 
ber, and November. 
In all cases, the period of 
maximum occurrence is responsible for at least 
75% of all occurrences. 
Unlimited ceilings are uncommon because of the 
extensive coverage of cumuliform clouds that per- 
sists over the Area. 
Ceilings of 5,000 to 6,000 feet 
are almost always observed, especially during the 
daylight hours. 
The usual daily pattern is a con- 
stant buildup in cloudiness to an afternoon maxi- 
mum. 
Activity, such as aerial photography, that 
is concerned with amount of cloud will find the 
early morning the most advantageous time. 
Statistical information on ceiling heights and 
cloud cover is given in Figures 23-16 and 23-17. 
These figures, concerned with established mini- 
mums for aircraft operation, identify the more 
restrictive flying regions in the Area. 
The Flo- 
rianopolis, Pelotas, Porto Alegre, and Sao Paulo 
regions, according to FIGURE 23-16, are the most 
often affected by ceilings below 1,000 feet. 
| 
b. VISIBILITY — Southeast Brazil is favored by 
unusually good visibilities; the most common re- 
striction is precipitation. 
During rainy periods, 
early morning fog is a frequent occurrence but it 
rarely lasts for more than a few hours. 
The heat 
of the day dissipates the fog be’). .'‘00 LST. 
Restricted visibilities exr* 
_ 
°zraphical a d 
seasonal variations. 
The svul «1. portion of the 
Area has a greater frequency 
_estricted visibility 
than other portions of the £ 
a. 
This particular 
yegion, in the highlands of 
ie south and close to 
the coast, experiences the .vorst flying weather in 
all of Southeast Brazil. 
This maximum 
of poor 
flying conditions is caused mostly by maritime air 
rapidly lifted by the terrain. 
The remainder of the Area is favored by unre- 
stricted 
visibility 90% of the time. 
Restricted 
visibility for 10% of the time results from rain 
showers that occur during the summer season. 
Visibility data are presented tabularly in FIGURES 
23-18 and 23-19. 
In summary, air-ground operations would sel- 
dom be handicapped by restricted visibility; the 
small percentage 
of the time that visibility is 
restricted is confined to the rainy periods. 
In the 
southern portion of the Area, poor visibility and 
low ceilings are usually a result of frontal weather 
during the winter season. 
c. LOW-LEVEL 
TURBULENCE — This 
Area, 
lo- 
cated almost entirely in the tropical zone where 
temperature variation is generally slight, experi- 
ences almost constant low-level turbulence and 
instability during the afternoon hours. 
Opera- 
— 
| 
} 
t 
‘ 
|
AIR FORCE —- OCTOBER 1954 
tional activity handicapped by low-level turbu- 
lence and instability should be planned for night 
or early morning hours. 
3. Ground surface operations 
a. PRECIPITATION — As far as precipitation is 
concerned, the climate of Southeast Brazil can be 
divided into wet and dry seasons. 
TheSe seasons 
are not simultaneous in all regions but shift from 
summer to winter in different locations throughout 
the country. 
Along the northeast coast, for exam- 
MILITARY GEOGRAPHY 
ple, the wet season is in winter, and farther south 
© 
in the vicinity of Rio de Janeiro the wet season is 
in summer; still farther south near the boundary 
of Uruguay the seasons lose their identity. 
Fur- 
ther differentiation in the wet season is apparent 
in an inland direction, where the wet season tends 
to occur in summer. 
Most stations in Southeast 
Brazil report an 
annual average rainfall of 30 to 80 inches. 
The 
heaviest amounts of rain occur in the southern 
highlands, where an annual average of 147 inches 
is normal. 
Of unusual interest is the interior of 
the northecst part of the Area. 
Here, the yearly 
rainfall mcy be as low as 10 inches per year com- 
pared to €) to 80 inches a year in the surrounding 
regions. 
For 2 or 3 consecutive years there is an 
ahunvance of rainfall, then for 2 or 3 years prac- 
tical y no rain falls. 
The paralyzing effect of these 
raini°ss years on agriculture, stock raising, and 
hun 
 -ndeavor can readily be imagined. 
Tit 
>ughout the Area, precipitation is mainly in 
the fo n of showers. 
are cc aparatively rare, the cumulus clouds com- 
mon tu fi:e Area are large enough to create numer- 
ous ra’.. showers. 
Large amounts of rain confined 
to relatively short periods of time present drain- 
age problems, especially in the highland regions. 
The more level portions of the northeast readily 
absorb large amounts of moisture, alleviating these 
problems. 
The danger of flash floods in the high- 
lands where thunderstorms are more common is 
always a hazard during the wet season. 
FIGURES 
23-20 through 23-22 present precipitation data in 
While actual thunderstorms 
tabular form. 
Mean monthly precipitation 
for 
| 
selected stations is shown repeoey in FIGURE 
23-3. 
Although snow has occurred as far north as Rio 
de Janeiro, its occurrence cannot be considered 
normal in any portion of this Area. 
The possi- 
bility of occasional snow during the winter season 
Note 
Many of the climatic elements, acting either 
alone or in combination, affect ground surface 
operations. 
The most important are precipita- 
tion, temperature, relative humidity, and surface 
winds. 
Reference can be made to Subsections 
B, 1 and B, 2 for discussions of other meteor- 
ological elements affecting surface operations to 
some degree. 
does exist in the extreme south, but even here many 
years pass without snowfall being recorded. 
For the effect of precipitation on the state of the 
ground and the resulting effect on the mobility of 
equipment and troops, reference should be made to 
SECTION 24, Topography. 
_ 
b. TEMPERATURE — This portion of Brazil has 
remarkably uniform temperatures in spite of its 
wide latitudinal range. 
Along the coast and north 
of the Tropic of Capricorn the annual average 
temperature varies between 75° and 80° F. 
In the 
extreme southern portion of the Area the annual 
average falls to 65° F. 
The 15-degree areal range 
in annual temperature is quite small considering 
the 30-degree latitudinal range of the Area. 
Throughout most of the Area the range between 
Summer and winter average temperatures is about 
10° F. 
(Ficure 23-23). 
The extreme southern 
portion of the Area experiences the only deviation 
from this general picture; here a range of 20° to 
30° F. is normal. 
Temperatures in the highland 
regions inland from the coast average 5° F. less 
than temperatures in corresponding regions on 
the coast itself. 
FIGURE 23-24, which presents mean maximum 
and minimum temperatures-for selected locations 
in Southeast Brazil, is of interes’ to planners of 
ground operations for a number of reasons. 
In- 
formation such as the expected range of daily tem- 
peratures, the limits between which the tempera- 
ture can be expected to vary, and the seasonal 
trends of temperature are readily apparent in the 
table. 
These factors are of interest to construc- 
tion, storage, sanitation, troop comfort, and pos- 
sibly many other ground 
activities. 
Generally 
speaking, the northern and central sectors experi- 
ence relatively high mean maximum temperatures 
during all months; the southern sector experiences 
its high mean maximum in the summer. 
Jet air- 
craft operating in areas where high surface temper- 
atures are frequent require longer runways than 
conventional aircraft. 
The mean maximum tem- 
peratures common to this entire Area during the 
summer and to the northern and central sectors 
during all seasons, combined with the high fre- 
quency of light surface winds, identify the Area as 
one where long runways will be necessary if jet 
operations are contemplated. 
Mean minimum temperatures are lowest in the 
southern sector and become progressively warmer 
in a northerly direction. 
Incursions of cold air 
from the south during the winter season are re- 
flected in the winter depression of mean minimum 
temperatures in southern 
sectors. 
This winter 
minimum is also evident in the central and north- 
ern sectors but is not as pronounced as in the south. 
Minimum temperatures are also relatively high 
PaGE 23-5 
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QUIXERAMOBIM 
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IMPERATRIZ 
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(77 $430 
RIO DE JANEIRO 
SOUTHEAST 
BRAZIL 
SAO PAULO 
rt 
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| 
$235 
FIGURE IN PARENTHESES IN LOWER 
SANTA VITORIA. 
LEFT HAND CORNER OF EACH GRAPH 
INDICATES YEARS OF RECORD 
> 
Area Boundary 
Z2E 
_—.. International Boundary 
lie $232 
a. 
FIGURE 23-3. MEAN MONTHLY PRECIPITATION (INCHES). 
(For tabular data see F1icurE 23-20.) 
| 
|
FORCE — OCTOBER 1954 
throughout the Area as the tropical nature of the 
Climate would indicate. 
FIGURE 23-25, a table of absolute maximum and 
- minimum temperatures, is included primarily for 
the information it presents on freezing tempera- 
tures. 
Freezing temperatures are confined to the 
southern portion of the NIS Area and are reported 
infrequently even in this region. 
The extreme low 
from the data presented is 20° F.; since this table 
is one of absolute minimums, 20° F. temperature 
can be reasonably called an unusually low tem- 
perature. 
The mildness of the temperature regime 
in the Rio de Janeiro area is indicated by the fact 
that minimum temperatures have 
never 
been 
below 50° F. in 49 years of record. 
Graphical presentation of mean and absolute 
maximum and minimum temperatures appear in 
FIGURES 23-4 and 23-5. 
| 
c. RELATIVE HUMIDITY — Relative humidities 
maintain a high annual average for most locations 
in Southeast Brazil as indicated in FIGURE 23-26. 
Excluding Quixeramobin where the annual aver- 
age is 61%, all stations listed in the table have 
annual averages of 70° 
or greater, a positive indi- 
— 
cation of high moist’ 
e content in the air masses 
that dominate the / 
a. 
Seasonal trend —_ relative humidity are hard to 
distinguish on 
° 
i basis; monthly variation 
relative 
‘is apparently a function of 
geographic 
4. °.vn 
and 
local wind 
direction. 
Generally, relative humidities are high throughout 
the region with rather nominal month-to-month 
variation. 
The combination of high temperatures and high 
relative humidities results in oppressive and un- 
comfortable living conditions in the greater por- 
tion of this Area. 
The same combination favors 
rapid decay of perishables, mildew and rust of 
equipment, and health problems due to stagnation, 
fatigue, and sanitation. 
Operations planned for 
this Area should include countermeasures against 
these conditions. 
The persistently large quantity of water vapor in 
the air causes copious amounts of dew to form in 
many places during nocturnal hours; moisture 
penetrating the soil for a depth of 4 inches has 
been measured after a particularly heavy dew. 
d. SURFACE WINDs — In Southeast Brazil, sur- 
face winds are extremely weak. 
FIGURES 23-27 and 
23-28 give tabularly the mean daily surface wind 
velocity and the prevailing direction of surface 
winds, 
respectively. 
Surface 
wind 
roses 
for 4 
months representative of the 4 seasons are illus- 
trated in Ficures 23-6 through 
23-9. 
In the 
northern and southern regions, wind speeds aver- 
age 5 to 8 knots; in the central region, the annual 
average is 3 to 4 knots. 
This entire Area has a 
MILITARY 
GEOGRAPHY 
high frequency of calm conditions; 
high wind 
speeds are related to thunderstorm activity, during 
- 
which speeds as high as 40 knots may be attained 
for short periods of time. 
Surface wind directions in Southeast Brazil are 
dependent largely on local terrain. 
Most of the 
coast is affected by land and sea breezes, which, 
though weak in character, do serve to make more 
comfortable living conditions. 
€. OVERALL EFFECT OF SURFACE WEATHER PHE- 
NOMENA ON CLOTHING, STORAGE, AND SHELTER 
(1) Clothing — Throughout the Area, cloth- 
ing requirements which are most significantly in- 
fluenced by temperature, humidity, and precipita- 
tion, differ as a result of the climatic changes asso- 
ciated with elevation and latitude. 
The latitudinal 
range is more than 30°, and altitude varies from 
sea level to almost 9,500 feet. 
In spite of these 
factors, the range of clothing items needed for 
year-round environmental 
protection 
is not as 
great as might be expected. 
The fact that most 
of the Area is within the tropics has an equalizing 
effect on clothing requirements. 
Some special 
items are required because of the prevalence of 
disease-carrying insects and pests. 
FIGURE 23-10 gives the clothing assembly most 
desirable for wear in certain regions during each 
month of the year. The regions, each of which has 
its own distinctive clothing requirements, are the 
Coastal Lowlands, discontinuous bits of coastal 
plains, and the Eastern Plateau, the highlands 
which make up most of the Area. 
The clothing requirements tabulated in F1iGuURE 
23-10 are expressed in terms of the following three 
clothing assemblies, which have been prescribed 
for worldwide use depending upon the occurrence of 
the specified mean monthly temperatures: 
MEAN MONTHLY 
CLOTHING ASSEMBLY 
TEMPERATURE 
Warm-weather 
ove 68° F. 
Cold-weather 
. 
14° to 50° F. 
For planning purposes the components of the 
clothing 
assemblies* 
are 
described 
in general 
terms. 
The warm-weather assembly is a cotton 
outfit (visored cap, shirt, trousers, and underwear). 
It also includes a lightweight woolen knit shirt, 
primarily for night wear; a sun helmet; and light- 
weight canvas high-top boots. A single woolen 
blanket is adequate sleeping equipment for use 
with this assembly. 
In the cool-weather clothing assembly, flannel 
or woolen items are substituted for the cotton shirt 
and trousers, high-top leather boots, for the canvas 
* 
Appropriate service regulations list the exact no- 
menclature and the basis for issue of the various 
components of the clothing assemblies. 
PAGE 23-7 
» 
| 
q 
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\
QUIXERAMUBIM 
{100 
EE: 
<3 8 
Yrs. Record: 8 
Yrs. Record:i6-19 
IMPERATRIZ 
CAETITE 
Yrs. Record: 
SALVADOR 
Yrs. 
VACARIA 
SANTIAGO 
SOUTHEAST 
BRAZIL 
SAO PAULO | 
| 
| 
MEAN DA.LY 
| a 
TEMPERATURES (*F) 
| 
| 
(OBSERVATIONS AT 
Yrs. Record: 44 
MINIMUM 
(OBSERVATIONS AT O7OOLST) 
SANTA VITORIA 
00 PALMAR 
aus 
Areo Boundary 
International Boundary 
| 
Yrs. Record: 
FIGURE 23-4. MEAN DAILY MAXIMUM AND MINIMUM TEMPERATURES 
(°F'.). 
(For tabular data see F1icurE 23-24.) . 
rom... 
| 
SAO Luis 
| 
| 
\ 
/ 
IBARRA DO CORDA 
so 
| 
FERNANOO 
Yrs. Record: 7 
\ 
| 
Hil 
| 
PiRapoRA 
| 
| 
| 
=< 
| 
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Yrs. Record: 12-20 
| 
| 
| 
| 
Yrs. Record:9-'5 
| 
| 
Jd 
| 
| 
| 
| 
UBERABA 
| 
100 
| | | 
| 
| 
| 
: 
| 
| 
| 
$238 
| 
| 
| 
| 
| 
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| 
RIO DE JANEIRO 
| 
| 
| 
Te) 
Yre. Record: 
q 
+ 
: 
| 
| 
| 
| 
| 
| 
|
FORCE — OCTOBER 1954 
MILITARY GEOGRAPHY 
| 
SAO Luis. 
BARRA DO CORDA 
100 + 
[FERNANDO 
100 
80 - 
rir 
QUIXERAMOBIM 
100 - 
60- 
Pele 
| 
40 - 
40 - 
| 
20- 
60+ 
| 
20- 
a 
YRS 
= 
20- 
T 
> 
YRS. Record: 9 
YRS. Record: 24 
IMPERATRIZ 
| 
| 
| 
ee 
NATAL 
100 - 
CAETITE 
80 - 
100 
40 - 
| 
YRS. Record: 
80 - 
20- Ht 
SALVADOR 
\ 
| 
> 
20- 
YRS. 
wr 
80- 
- 
| 
YRS. Record: 
UBER ABA 
a 
o 
z 
80 + 
YRS. Record: 
| 
Tre ||| 
RIO DE JANEIRO 
80 - 
YRS. Record: 7 
40 - 
20- 
o 
z 
YRS. Record: 49 
SKO PAULO 
SOUTHEAST 
BRAZIL 
60- 
1004, 3 
1] 
ilies 
60- 
| 
— 
> @ 50 
ABSOLUTE 
TEMPERATURES (°F) 
YRS. Record: 44 
"GANTA VITORIA 
(OBSERVATIONS AT 1400 LST) 
< 
‘ 
ae 
YRS. Record: 34 
@ 
MINIMUM 
a0 
(OBSERVATIONS AT O700 LST) 
International Boundary 
YRS. Record: 35 
; 
MAXIMUM 
MINIMUM 
FIGURE 23-5. ABSOLUTE 
AND 
TEMPERATURES (°F.). 
(For tabular data see F1icurE 23-25.) 
a 
| 
| 
a 
&
FERNANDO DE NORONHA 
TERESINA 
(7-9) 
j 
(2-8) 
(2-4) 
| 
\ 
| 
| 
SALVADOR 
CAETITE 
| 
| 
PIRAPORA 
| 
(2-5) 
TEOFILO 
UBERABA 
(2-8) 
(9-11 
JANUARY 
PERCENTAGE 
| 
FREQUENCY 
¥, 
CALM 
| 
| 
10010 
$0. 
| 
PERCENTAGE FREQUENCY 
SCALE 
| ven 
FIGURE IN PARENTHESES INDICATES 
YEARS 
OF RECORO 
aus Areo Boundary 
SANTA VITORIA DO PALMAR 
—-— 
international Boundary 
FIGURE 23-6. SURFACE WIND ROSES, JANUARY 
PAGE 23-10
AIR FORCE — OCTOBER 1954 
MILITARY GEOGRAPHY 
d 
( 
| 
) 
| 
| 
| 
\ 
mee 
J 
| 
| 
| 
+ 
4,— 
FERNANDO DE NORONHA 
(7-9) 
| 
| 
| 
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SALVADOR 
| 
(9) 
| 
-10) 
(2-5) 
TESFILO OTON, 
i 
AL, 
RIO DE JANEIRO 
SOUTHEAST 
BRAZIL 
| 
OSES 
f 
SURFACE WIND ROSE 
(6 -9) 
APRIL 
GUARAPUAVA 
TAGE 
(6-9) 
| 
| 
PERCENTA 
| 
= 
FREQUENCY 
| 
CALM 
PORTO ALEGRE 
PERCENTAGE FREQUENCY 
(9-4!) 
| 
SCALE 
MRUGUAIANA 
| 
32- 
FIGURE IN PARENTHESES INDICATES 
YEARS OF RECORD 
Areo 
Boundary 
FIGURE 23-7. SURFACE WIND ROSES, APRIL 
i 
=
NIS 
94-I 
FORCE — OCTOBER 
| 
| 
| 
: 
) 
| 
/ 
| 
| 
) 
| 
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BARRA DO CORDA 
-4) 
FERNANDO DE NORONHA 
TERESINA 
NATAL 
(4) 
\ 
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| 
| 
(2-10) 
l2 
| 
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SALVADOR 
| 
| 
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— 
PIRAPORA. 
TEOFILO OTON: 
UBERABA 
(6-6) 
| 
(2-8) 
we 
RIO DE JANEIRO 
| 
SOUTHEAST 
BRAZIL 
(9-11) 
R 
WIND ROSES 
it 
SAO PAULO 
SURFACE 
WIN 
t 
(6-9) 
JULY 
“3 
GUARAPUAVA 
= 
PERCENTAGE 
(6-8) 
| 
FREQUENCY 
| 
| 
10010 
30° 
$0 
| 
PBRTO ALEGRE 
| 
PERCENTAGE FREQUENCY 
ay 
URUGUAIANA 
©. 
(9-41) 
SCALE 
» 
(4-8 
| | FIGURE IN PARENTHESES INDICATES 
YEARS 
OF RECORD 
que 
ees Areo Boundory 
SANTA viTORIA 
—.. Internotional Boundary 
FIGURE 23-8. SURFACE WIND ROSES, JULY 
PAGE 23-12 
| 
| 
| 
e 
‘ 
| 
| 
‘ 
‘ 
- 
=
— 
a7 
Arr ForcE— OCTOBER 1954 
MILITARY 
GEOGRAPHY 
BARRA DO CORDA 
QUIXERAMOBIM 
(2-3) 
(2-4) 
TERESINA 
(2-8) 
SALVADOR 
(9) 
é 
CAETITE 
| 
| 
(2-10) 
PIRAPORA 
(2-8) 
© 
TEOFILO OTONI! 
(6-8) 
UBERABA 
RIO DE JANEIRO 
(2-5) 
| 
ii) 
j 
Fa 
SOUTHEAST BRAZIL 
SURFACE WIND ROSES 
OCTOBER 
GUARAPUAVA 
FREQUENCY 
| 
CAI.M 
| | 
10 010 
30. 
$0 
| 
PERCENTAGE FREQUENCY 
FIGURE IN PARENTHESES INDICATES 
afm 
YEARS 
OF RECORD 
aus 
Areco Boundary 
SAMTA 
00 PALMAR 
international Boundary 
| 
Ficure 23-9. SURFACE WIND ROSES, OCTOBER 
| 
| 
one 
| 
| 
| 
| 
| 
| 
| 
| 
| 
| 
| 
| 
| 
| 
| 
| 
I 
| 
| 
| 
fis 
| 
| 
| 
| 
| 
| 
/ 
sko wis” 
(2-4) 
| 
| 
| 
\ 
FERNANDO DE NORONHA 
| 
| 
(7-9) 
| 
\ 
| 
| 
/ 
| 
| 
| 
| 
: 
| 
| 
| 
| 
| 
; 
| 
| 
| 
| 
|
boots, and a high-necked, long-sleeved sweater for 
the woolen knit shirt. 
A hooded, water-repellent, 
wind-resistant 
jacket and 
leather 
gloves with 
woolen inserts are included. 
A woolen sleeping 
bag with a water-repellent case is adequate sleep- 
ing equipment for use with this assembly. 
The cold-weather assembly includes the items 
of the cool-weather assembly plus a pile jacket to 
be worn under the water-repellent, wind-resistant 
jacket; 
water-repellent, 
wind-resistant 
cotton 
trousers to be worn over the woolen trousers; a 
woolen muffier; and white parka, trousers, and 
mittens to be worn over the outer clothing items 
in snow-covered revin’s. 
Winter underwear 
is 
substituted for the ~o..on underwear; a cotton 
visored cap with pul: town flaps for the cotton 
visored cap; and boots .imilar to the U.S. Army 
combat, rubber, insulated boot with one pair of 
woolen cushion sole socks for the high-top leather 
boots. 
A mountain-type sleeping bag (down- and 
feather-filled) with a water-repellent case is nor- 
mally used with this assembly. 
A lightweight poncho is desirable with each as- 
sembly for protection against rain. 
These clothing assemblies have been computed 
on the assumption that the individuals wearing 
them will be living in the open for 24 hours a 
day. 
Requitements for individuals in permanent 
installations may differ somewhat; for instance, 
a raincoat may be more practical than the poncho, 
and the service-type shoes with one pair of me- 
diumweight woolen socks and a pair of overshoes 
might be more desirable than the high-top leather 
boots. 
The prevalence of insects and pests (mosquitoes, 
flies, ticks, lice, fleas, gnats, scorpions, centipedes, 
and tarantulas), and snakes make certain special 
items necessary. 
For example, repellents, insect 
bars, headnets, mosquito gloves, and similar items 
afford some protection against insects and pests. 
High-top boots or leggings afford some protection 
against snakes. 
NIS 
94-I 
AIR FORCE —- OCTOBER 1954 
Numerous swamps along the coast and in the 
interior, particularly in the southern portion of 
the Area, may impose a requirement for some 
type of waterproofed footwear during the winter. 
Blowing dust and sand is a nuisance in the 
northern interior, particularly during the sum- 
mer. Some type of face and neck shield gives some 
protection against this condition. 
The long periods of brilliant sunshine in the 
Area suggest a requirement for tinted glasses. 
Generally, winter is the sunniest season except 
in the extreme northern and southern portions, 
where summer is the sunniest. 
High humidities cause rapid deterioration of 
untreated cloth or leather items throughout the 
year along the coast and during summer 
in 
the interior. 
(2) Storage — Extremes 
of 
temperature, 
precipitation, high humidity, and strong winds 
are the main environmental factors to be con- 
_ sidered for protection of open-stored items in the 
NIS 94-I Area. 
Open-stored subsistence 
supplies, unless pro- 
tected, 
are 
subject 
to damage from 
alternate 
freezing and thawing during the winter in the 
southern portion of the Area, particularly above 
2,000 feet on the plateau. 
Also, they suffer dam- 
age from high temperatures throughout the Area 
except at higher elevations and, during the win- 
ter, in the southern portion (above 2,000 feet on 
the plateau). 
Protection of open-stored items against rain is 
desirable throughout the Area during the entire 
year, except during the summer in the extreme 
north. 
Except in the interior during winter, 
stored items are subject to damage from rust 
and mildew because of high humidity. 
Flood plains adjacent to rivers are dangerous 
for use as storage sites, especially during the rainy 
seasons. 
Marshes and swamps, mostly in the 
south, also limit the availability of storage sites. 
Wood for dunnage is available throughout most 
23-10. CLOTHING REQUIREMENTS 
REGION 
aN | FEB | MAR | aPR | may | gun | guL | avo | sep | ocr | Nov | pEc 
CoastaL LOWLANDS: 
Noven 
Frio............. 
Ww 
Ww 
Ww 
WwW 
WwW 
WwW 
Ww 
WwW 
W 
Ww 
WwW 
WwW 
South of Cabo Frio............. 
WwW 
WwW 
WwW 
Ww 
C 
C 
C 
C 
C 
C 
WwW 
EASTERN PLATEAU: 
Northern portion: 
Below 2,000 feet.............]| 
W 
Ww 
Ww 
w 
Ww 
Ww 
Ww 
Ww 
WwW 
2,000 to 5,000 feet............ 
W 
WwW 
WwW 
C 
C 
C 
C 
C 
W 
Above 5,000 feet............. 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C. 
C 
C 
Southern portion: 
Below 2,000 feet..............]| 
W 
W 
WwW 
C 
Cc 
C 
C 
C 
C 
WwW 
2,000 to 5,000 feet............ 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
Above 5,000 feet............. 
C 
C 
C 
C 
D 
D 
D 
D 
D 
C 
C 
C 
W — warm weather clothing assembly; C - cool weather clothing assembly; D — cold weather clothing assembly. 
‘PaGE 23-14 | 
| 
|
the year. 
and wall tent provide adequate protection through- 
1% of the obse 
AIR FORCE — OCTOBER 1954 
of the Area; it is scarce or lacking in the north 
and central interior and in the extreme south. 
(3) Shelter — Shelter is needed throughout 
Tents similar to the U.S. Army squad 
out most of the Area. 
Heat is desirable at higher 
elevations throughout the year and in the south 
during winter. 
Tents are needed for protection 
against rain and cool temperatures as well as 
for shade. 
The prevalence of insects and pests 
throughout the Area makes screened tents de- 
sirable. 
Timber for construction of improvised shelter 
and for framing or flooring of tents is available 
throughout most of the Area; it is lacking or 
scarce in the north and central interior and in 
the extreme south. 
| 
4. Amphibious operations 
a. NoRTH oF Nata — Off the coast of Forta- 
leza, northeasterly winds prevail from January 
through April, and southeasterlies, from June 
through November. 
than 11 m.p.h. during all seasons. 
The northeast 
trades are strengthen: . by a sea breeze during the 
day, and a weak < .thwesterly land breeze de- 
velops for a few } 
.rs during the night. 
Gales 
(winds speeds ov 
28 m.p.h.) occur in less than 
Southeast :'v 
ells and seas prevail 50% to 
10% of the tir... from March through October, 
50% of the time from December through January, 
and 35% to 40% of the time in November and 
February. 
Northeasterly swells and seas are at 
a maximum in November, when 60% is observed, 
and at a minimum in July and August, with 20% 
being observed. 
During other months, northeast- 
erly swells and seas prevail about 30% to 40% 
of the time. 
Slight to moderate swells and seas 
prevail 82% to 98% of the time except from Jan- 
uary through April, when heavy or confused swells 
and rough seas are reported in 10% to 17% of the 
observations. 
Mean sea-surface temperatures of 79° to 82° F. 
are reported throughout the year. 
b. NATAL SOUTH To 20°S. — Off the coast south- 
ward to the latitude of Ilhéus, southeast trade 
winds predominate during all seasons, with north- 
Note 
Amphibious operations include all phases of op- 
erations involving the movement of troops and 
equipment onto a beach and the associated pro- 
tective 
measures. 
The 
discussion 
of coastal 
weather covers such pertinent elements as sur- 
face winds, swells and seas, and temperature. 
Discussion 
of other 
pertinent 
meteorological 
elements such as cloudiness, visibility, and pre-— 
cipitation may be found in the Subsections on 
Air, Air-ground, and Ground Surface Operations. 
MILITARY GEOGRAPHY 
The mean wind speed is less — 
east to southeast winds occurring 90% to 95% of 
the time. 
to prevail during the remaining 30%. 
Land and 
sea breezes are weak, and the land breeze does 
not exist at all south of Salvador. 
On the coast, 
wind directions are variable due to topographic 
features. 
Mean wind speeds average 11 m.p.h. 
Gales occur in less than 1% of the observations. 
Swells and seas from the northeast to south- 
east quadrants prevail throughout the year, being 
observed 80% to 95% of the time, with slight to 
moderate intensity. Heavy or confused swells and 
rough seas are experienced 17% to 10% of the 
time from January through April and less than 
9% of the time from May through December. 
North 
of 10°S. the sea-surface temperatures 
average 78°.F. from July through November and 
81° F. from December through June. 
Farther 
south the temperatures remain about 80° to 81° F. 
from December through April, decreasing to 73° F. 
during the period June through November. 
c. SouTH or 20°S. — Winds offshore are pre- 
dominantly northeast during all seasons except 
south of Pérto Alegre from May through August, 
when winds from the southwest quadrant prevail. 
Mean wind speeds are 8 to 10 m.p.h. from Vitéria 
to Santos, increasing steadily southward to a mean 
of 11 to 14 m.p.h. 
Wind conditions on the coast are characterized 
by a high frequency of calms at sheltered ports, 
prevailing wind directions varying with the specific 
location, and occasional high winds of a local 
nature. 
Mean wind speeds are under 10 m.p.h. in 
all seasons. 
Gales occur in less than 5% of all 
observations. The greatest frequency of gale winds 
are observed from May through August between 
Cabo de Sao Tomé (21°59’S., 40°58’W.) and Cabo 
Frio (22°53’S., 42°01’W.) and in the vicinity of 
Rio de Janeiro. 
When squalls are observed they 
normally last for 5 to 6 hours. 
Gale winds are 
occasionally associated with the thunderstorms of 
southern Brazil’s winter season and the more in- 
tense cyclones that penetrate the coast from more 
southerly latitudes. 
Swells and seas from the northeast to south- 
east quadrants occur 70% to 85% of the time 
from September through November and from.Feb- 
ruary through March, with 40% to 65% in the 
remaining months. 
From the west quadrant, 
swells and seas are observed 20% to 25% of the 
time in December, January, July, and August. 
Swells and seas of slight to moderate intensity 
prevail 55% to 70% of the time. 
Percent occur- 
rence of heavy or confused swells and rough seas 
is 25% to 35% from June through August and 
Pace 23-15 
South of Ilhéus this condition holds | 
70% of the time, with a tendency for north winds 
|
less than 19% the remainder of the year except - 
for a secondary increase in December. 
Mean sea-surface temperatures range north - 
south 79° to 72° ¥. from December through April 
and 77° to 62° F. from May through November. 
23-16 
NIS § 
~ 
D. 
Climatic data tables 
The climatic data tables referred to in Subsec- 
tion B are contained in this Subsection. 
Most of 
“the data are limited to one, two, or three observa- 
— 
tions per day. 
Some of the data are limited to 
short periods of record. 
Data on ceiling heights 
and visibility restrictions are limited by both short 
periods of record and paucity of stations at which 
they are recorded. 
Due to rounding off of decimal values, annual 
totals or means may not agree exactly with the 
sum or mean of the monthly values. 
The meteorological stations referred to in this 
Section are indicated in FicguRE 23-29, a map of 
station locations with an accompanying list giving 
latitude, longitude, and elevation of each station. 
The coordinates given are those of the meteorologi- 
cal stations and not necessarily those of the cities, 
settlements, or other geographical features for 
which they are named. 
~ 
The data contained in the tables in Subsections 
B and D were obtained from unclassified sources. 
- 
» 
) 
‘ 
‘ 
| 
‘ 
| 
: 
’ 
,
AIR FORCE — OCTOBER 1954 
MILITARY 
GEOGRAPHY 
FiguRE 23-11. MEAN CLOUDINESS (%) 
na 
Data not available. 
* 
Near but outside NIS 94-I Area. 
PAGE 23-17 
STATION 
jan | FEB | MAR | 
| May | gun | 
| ava | sep | ocr | nov | pec | ann 
|YRSREC 
11-18 
CE: ee 
a 
ee 
54. 
na 
na 
2-4 
os 
ct 
2-7 
Ber monsonte.. 
i. ss: 
. 
16-21 
9-11 
15-21 
Er ia 
ae 
. 
2-3 
14-21 
67. 
~=—«60 
6-8 
Ny foe 
ee 
ae 
ore 
10-14 
64. 
na 
na 
2-3 
ci 
ee 
kG 
58° 
Diamantina........ 
, ee 
3-5 
sy 
Seb 
7-8 
MC 
es 
ee 
Or ea 
core 
= 66 
10-12 
SESS 
er ae eee 
583 
IE os 
AS ean 
6-9 
SEES 
Me eee 
8-11 
a...) 
17-20 
MRS epi 
s ay 
na 
na 
na 
na 
nee 
ee be Eas 
17-19 
I 
oe 
ay 
12-16 
eke, 
ce 
er 
ye 
he 
5} 
Presere G6 Mats... .5........ 
ee 
ee. kk Frees 
3-11 
(SSCS 
EE OE 
6) 
20-23 
+50 
9-10 
a os 
9-13 
SDE 
2-3 
sie ianens vee 
of 
2-5 
Guiseramobim. 
; 2... ......%. 
28-30 
i 
15-20 
SS ane 
ae ren 
19-20 
Me ee TO. 
40-42 
eee 
2-4 
Ee 
#66 
3-4 
We 
ak: na 
na 
na 
na 
10-13 
Santa Vitéria do Palmar...... 
na 
10-12 
PM ne 
ce ts 
14-18 
OS ee 
nee 
ae 
na 
I ies 
pes he 
24-27 
15-17 
ORR eesrerecesrnrrseceimennenn 
na 
na 
2-8 
a 
wy 
9-12 
Urussanga........ 
“6 
na 
pare 
aa ore 
3-8 
? 
-
NIS 94-1 
Arr Force 
OcToBer 1954 
FicurE 23-12. MEAN NUMBER OF CLEAR DAYS (CLOUD COVER =2-TENTHS) 
BTATION 
JAN | FEB | MAR| APR | MAY | JUN | guL | ava 
| seP | ocr | Nov | 
ANN | YRS REC 
Fernando de Noronha........ 
ia 
°3 
] 
MS Siac cise 
eee es 
Guaramiranga.......... 
l 
142 
% 
l 
are 
aera rarer 
162 — 
] 
Pérto Alegre......... es 4 bg 
an 
NS Se 
ae eee 
] 
l 
l 
FicgurE 23-13. MEAN NUMBER OF DAYS WITH THUNDERSTORMS 
STATION 
| FEB | MAR | aPR | May | sun | 
| ava | sep | ocr | Nov | pec | 
| YRS REC 
EEE 
EE 
EE 
we 
] 
ey 
cia es 
l 
i 
se: oe bas 
= 
] 
l 
Barra do Corda..... 
l 
na 
Belo Horizonte... . 
we 
- 
na 
l 
l 
l 
] 
4-5 
Campos...... 
pe 
eas 
0 Oa 0 
l 
] 
Fernando de Noronha........ 
l 
rn 
- 
Wes 
na 
nana 
na 
=~*na 
=~*na 
| 
na 
ESSE 
Se 
oe 
] 
l 
117 
] 
] 
Nazaré da Mata............. 
ee rs 
ee ee 
os Bsn vine wi 
] 
l 
aa 
] 
Porte hegre: 
rrr rrr 
Quixeramobim.............. 
] 
a 
i 
ae 
l 
SE 
OS eet 
l 
] 
7-8 
ee 
na 
Data not available. 
* 
Near but outside 94-I Area. 
- 
ee...
~ 
AIR FORCE 
— OCTOBER 1954 
MILITARY 
GEOGRAPHY 
FigurRE 23-14. AVERAGE WINDS AT SPECIFIED ALTI- 
TUDES, BY DIRECTION AND SPEED 
(DEGREES/KNOTS) 
ALTITUDE| WINTER | SPRING |SUMMER|AUTUMN 
feet 
North of 10°S....| 
20,000 | 330/5 
360/4 
010/3 
30,000 |} 090/6 
090/5 
0090/4 
090/5 
10°S. to 20°S.....| 
20,000 | 330/7 
 360/3 
010/3 
30,000 | 270/6 
270/3 
V/4 
270/5 
South of 20°S....| 
20,000 | 290/15 
270/9 
270/12 
300/8 
30,000 | 270/25 
270/20 
270/15 
270/20 
V - Variable. 
Figure 23-15. MEAN TEMPERATURE 
(°C.) AT SPECIFIED ALTITUDES 
ALTITUDE| 
ALTITUDE| JAN | APR | guL | ocr 
STATION 
| 
san | apr | sun | ocr 
BTATION 
feet 
Belo Horizonte........... 
10,000 
10,000 
18 ,000 
—-8 
-10 
-7 
18 ,000 
—4. 
-—6 
30,000 | —32 
-32 
-—34 
-—33 
30,000 | —32 
-—31 
-—32 
40,000 | —53 
-52 
-—52 
-—852 
40,000 
| —52 
-—54 
—53 
45,000 | —64 
-—-63 
-—62 
-—6l 
45,000 | —64 
-—-66 
-—64 
—66 
65,000 | —72 
-—70 
-—69 
—69 
10,000; 
#8 
10,000 
18,000 
—-8 
-4 
-6. 
18 ,000 
-8 
-—16 
—12 
30,000 | —32 
-—30 
-—32 
-—30 
30,000 | —34 
-—37 
40,000 | —53 
-52 
-—54 
-—53 
40,000 | —53 
-—54 
-—52 
—50 
45,000 | —64 
-66 
—64 
—67 
45,000 | —61 
-60 
-—58 
—53 
55,000 | —76 
-—77 
—76 
55,000 | —67 
-—-63 
-—62 
—60 
--| 
10,000 | 
Rio de Janeiro........... 
10,000 
30,000 | —32 
-—32 
-—33 
-—32 
30,000 |} —32 
-—34 
-—38 
—35 
40,000 | —52 
-—52 
-—52 
—52 
40,000 | —53 
-—53 
-—52 
-—5l 
45,000 | —64 
-—-64 
-—63 
—62 
45,000 | —63 
-—62 
-60 
—56 
55,000 | —73 
-—72 
-—70 
55,000 | —70 
.-—66 
-—-66 
—64 
10,000 
Santa Vitéria do Palmar...| 
10,000 
18,000 
-4 
-6 
-6 
18,000 
—-8 
-10 
-—-18 
-—14 
30,000 | —32 
-—31 
-—32 
30.000 | —36 
-—38 
-—44 
—40 
40,000 | —52 
-52 
-—53 
-—53 
40,000 | —53 
-—55 
-52 
—50 
45,000 | —64 
-—-65 
-—64 
—64 
45,000 | —60 
-—-59 
-—56 
—52 
55,000| 
—75 
-74 
—72 
—74 
55,000 | —64 
—61 
-60 
—58 
Figure 23-16. PERCENTAGE FREQUENCY OF SPECIFIED CEILINGS AND VISIBILITIES 
STATION 
| 
gan | ren | mar | apr | may | sun | suL | aua | sep | ocr | nov | DEC 
bi 
Camocim.....| 
Ceiling 
<1,000 
feet 
or} 
0.2 
0.0 
0.2 
0.9 
0.0 
0.2 
0.0 
0.0 
0.0 
0.0 
visibility <3 miles. 
| 
Ceiling <500 feet or visi- | 0.0 
0.0 
0.0 
0.0 
0.3 
0.0 
0.2 
0.0 
0.0 
0.0 
0.0 
0.0] 
bility <1 mile. 
| 
Noronha. 
visibility <3 miles. 
Ceiling <500 feet or visi- | 0.0 
0.0 
0.0 
0.6 
0.2 
0.1 
0.4 
0.0 
0.0 
0.0 
0.0 
0.0] 
bility <1 mile. 
visibility <3 miles. 
Ceiling <500 feet or visi- | 0.1 
0.0 
0.0 
O.1 
O.5 
0.4 
O.4 
O.2 
O.2 
0.0 
0.0 
0.0 
bility <1 mile. 
visibility <3 miles. 
| 
Ceiling <500 feet or visi- | 0.1 
0.0 
0.0 
0.6 
0.8 
0.3 
O.0 
O.1 
0.5 
0.1 
O15 
O.3] 
bility <1 mile. 
| 
Parnamirim...| 
Ceiling 
<1,000 
feet 
or | 1.0 
0.9 
0.7 1.8 
1.8 
7.8. 
2.3 
1.1 
0.1 
O.1 
visibility <3 miles. 
Ceiling <500 feet or visi- | 0.2 
0.1 
O.1 
O.1 
bility <1 mile. 
9.0 
6.07 
» 
a 
PaGE 23-19 
| 
-
AIR FORCE —- OCTOBER 1954 
NIS 
JAN | FEB | MAR | APR | mAY | gun | gut | ava | sep | ocr| nov | pEc 
x 
| 
FO 
m= 
WY SOT 
Sian 
SSH 
@¥G 
SSS 
SSS 
COW 
iD 
—— 
COS 
coco. 
ooo 
—) 
oo 
= 
SON 
SHA 
SSS 
SOS 
tones 
Coo 
cen 
COO 
ese 
SHO 
SOS 
SOS 
SOS 
SSCS 
RANGE| 
JAN | FEB | MaR| apr | may | gun | gut | ava | sep | ocr | nov | 
jAN | FER | MAR | APR | May | sun | 
| ava | sep | ocr | nov | 
FigurRE 23-17. MEAN NUMBER OF DAYS WITH CEILINGS <1,000 FEET 
Figur. 
23-18. MEAN NUMBER OF DAYS WITH VISIBILITY <1 MILE 
Figure 23-19. PERCENTAGE FREQUENCY OF SPECIFIED VISIBILITIES AT 0900 LST 
ON ATM 
VVV' 
VVV 
IVVV 
con Fonznooow 
MOMMA SNM 
WOOD 
ad 
Eg 
eli 
Q 
Ega M5 
- 2 
- 
Q 
& 
< 
PQ 0 By 
Ay Ay AY 
= 
man 
‘ 
Q 
& 
.0 
| 
.0 
| 
‘|
MILITARY 
GEOGRAPHY 
AtR FORCE 
OCTOBER 1954 
YRS REC 
ANN 
42.1 
na 
FicgurE 23-20. MEAN PRECIPITATION (INCHES) 
© 
jan | rep | maR| apr | May | sun | gut | ava | sep | ocr | nov | vec 
2.8 
2.1 
3.1 
5.8 
7.0 
4.2 
3.3 
9.8 
1.8 
11.9 
1.5 
(12.8 
2.6 
na 
na 
5.4 
5.7 
5.2 
3.3 
3.8 
2.7 
5.8 
8.7 
6.0 
4.5 
10.6 
5.9 
. 4.9 
10.7 
STATION 
Foz do Iguacu........ 
Fernando de Noronha. . | | 
Cal .pos. . 
Caraveras....:... 
Caxias do 
Barra do Cords. 
| 
Belo Horizonte. . . 
Barra. 
. 
Garanhunes....... 
Guaramirange........ 
Guarapuava...... 
Iguape. . 
Nazaré da Mata............. 
Imperatriz. 
.. 
Itapeva. 
Itaqui 
Jofio Pessoa......... 
Paranagué...... 
© 
| 
= ON 
CO 
Ge 
33 N 
NNN 
NN OO 
= 
WOONNr 
wea 
COON 
OO 
= 
= 
= 
= 
— 
— 
wom 
= 
cor 
WH 
~ 
= 
N 
CH 
PaGE 23-21. 
na 
na 
9.6 
na 
na 
6.9 
na 
2-3 
14: 
14-004 
4.4 
44. 
£84: 
BA: 
) 
15.0. 
12.1 
10.6 
7.7 
2.1 
2.1. 
2.2 
2.02.8 
10.2 
18.3] 
87.8 
AS 
BS: 
AL: 
BA: 
1661-09. 
410-8
~ 
NIS 
94-I 
FIGuRE 23-20 (Continued) 
AIR FORCE 
OCTOBER 1954 
STATION 
| FEB | maR| apr | may| sun | 
| ava | ser | ocr | nov | pec | ann’ 
|yRsREC 
pants Vitona Go Paimar......| 
3.6 
4.1 
#42 
8.86 
4.3 
#38 
2.4 
3.11] 
47.0 
16.6° 16.6 
14.2. 
13:3 
6.3 
7.8. 
6.8 
7.7. 
10.9 
12.2 
14.3 
14.6 | 142.0 
na 
Data not available 
FIGURE 23-21. MAXIMUM 24-HOUR PRECIPITATION (INCHES) 
STATION 
san | FEB | MAR | apr | May | gun | 
| ava | sep | ocr | Nov | pEc | ANN | YRSREC 
] 
3-1] 
] 
Fernan: 
.ic Noronha........ 
] 
] 
mee eh 
es 
) 
ee 
ne: 
Santa Vitéria do Palmar..... 
. ee 
* 
Near but outside 94-I Area. 
** 
<0.5 inch. 
; > 
|
AIR ForcE-OctToBer 1954 
= 
MILITARY 
GEOGRAPHY 
Ficure 23-22. MEAN NUMBER OF DAYS WITH PRECIPITATION =0.01 INCH 
+ 
BTATION 
san | rep | maR| apr | 
sun | sur | ava | sep | ocr | Nov | pec | ann” 
|yYRSRE 
Aracaju...... 
127 | 13-20 
ia 
eg 
) 
9. 
Oy 
ce ea 
] 
] 
| 
2-6 
ee ere 
5. 
116 
9-11 
ee 
1] 
£19 
106 
18-2] 
108 
9-11 
103 | 13-20 
] 
] 
3-4 
3 ee "oer ae 
q 
1] 
128 | 17-19 
Caravelas... 
180 
6-8 
] 
] 
1] 
104 
Caxias do 
| 
1] 
1] 
137 
na 
na 
2-3 
SN ie 
a 
] 
6h 
a 
1] 
eee 
11] 
3-5 
Fernando de Noronha... 
. 
q 
103 
Paormemoooe..... 0.6. 
1] 
131 
17-19 
WOOGIE. ee 
102 
1] 
109 
1] 
150 
8-10 
Guarabira. . . 
ee 
105 
(uaramiranga........:..:. 
1] 
1] 
1] 
180 | 10-12 
NS te 
142 
1] 
| 
Sa 
116 | 10-14 
81 | 8-10 
er 
1] 
176 
DE 
ee 
ere 
126 
a 
a as 
<a 
129 
res 
a 
1] 
93 | 17-19 
ee 
ss he Gs 
RG 
ek ee 
17. 
193 
235 
1] 
70 | 12-16 
SESE EERE, Ce | 
202 
ee 
fess oe okey 
179 
147 
paeers Ga Mata.........:.., 
. 
175 
9-10 
116 
9-14 
| 
12. 
-10 
120 
101 
I 
ee 
123 
. 
192. 
2-3 
SIR 
ga 
1] 
] 
79 | 26-28 
Gweramonim.............. 
79 =| 26-28 
ESN 
Soe ne 
1] 
167 
15-20 
1] 
165 
| 
21-24 
eR 
re 
1] 
1] 
128 
1] 
110 
I icetrrtiniiriecnncineeincinincismnan 
143 
— 
NE SLA i 
113 
I es 
es ee 
I 
a 
aa 
101 | 14-18 
go 
oe 
150 
161 
126 | 15-17 
reine 
2-7 
134 
9-12 
na 
na 
na 
~*na 
na 
(Ee 
Oe 
100 
3-7 
na 
Data not available. 
* 
Near but outside 94-I Area. 
PAGE 23-5
‘ 
NIS 
94-1] 
FIGURE 23-23. MEAN DAILY TEMPERATURE (°F.) 
AIR FORCE — OCTOBER 1954 
eg? 
STATION 
| reB | Mar | apr | may 
gun | 
| avo | sEP | ocr | nov | pec] 
ann | yRsreEc 
8] 
79 =| 14-21 
RSA 
era 
RCR 
2-4 
556 
na 
na 
na 
2-7 
GO 
ie... 
19: 
8] 
80 | 12-14 
Ree Sermons... 
70 | 21-24 
ep 
he 
9-11 
8] 
8] 
82... 
] 
S::...4 
74 | 19-21 
6-8 
72 | 11-15 
Dee. 
8] 
8a 
&3 
na 
2-3 
61° 
3-5 
Fernando de Noronha....... 
17-19 
Prrenopos..:.......032...;. 
69 | 17-19 
Fortaleza......... 
8] 
Franca..................... 
7] 
Garanhbuns.................. 
71 =| 10-12 
SS 
ee ee 
8] 
ry 
Guaramiranga......... 
10-12 
I ee 
a 
hg 
62 | 11-14 
8] 
8] 
8-10 
NE os 
g 
MS 
he ea 
ee 
I ea. 
68 | 17-19 
as 
fe 
..<.. 
Ja oat&o...... 
> Jenudria....:. 
a 
| 
13-16 
8679 
OEE EE 
ee mes 
8] 
8] 
2-6 
8] 
8] 
Nazaré da Mata..... HOSS 
erie 
9-10 
TEES 
oO aes 
ee 
9-13 
SEE LIE 
EEE 
Be 
9-13 
ee 
ae ee 
Wee, eee 
2-3 
eat 
2-5 
8] 
«885 
83 | 28-31 
EG 
as 
a 
8] 
8] 
ae 
79 | 15-20 
68 | 18-20 
aa... 
oe 
ee 
| 79-81 
So 
ce a 
1] 
ES Oe 
Ta 
aaa: 
BR 
61... 
ep 
ce 
68 | 14-17 
EE 
a ea 
ES 
oe nes 
pol gO ees 
74 | 15-17 
2-8 
na 
| ee 
3-8 
na 
Data not available. 
* 
Near but outside NIS 94-I Area. 
PAGE 23-24 
| |
i= 
* 
AIR FORCE — OCTOBER 1954 
FIGURE 23-24. MEAN DAILY 
MILITARY 
GEOGRAPHY 
MAXIMUM (OBSERVATIONS AT 1400 LST) AND MINIMUM apices AT 
0700 LST) TEMPERATURES (°F.) 
STATION 
JAN | FEB | MAR | apr | may | suN | yur | ava | sep | ocr | NOV | DEC | ANN | YRS REC 
ASGGEIE. 
6 Rs 
Max 
13-20 
RPGR 
3 i 
Max 
Min 
ee 
Se 
RPRPEROUR ci fies 
‘Max 
2-4 
Min 
ae 
ee 
na 
2-4 
Max 
Min 
>) 
ae 
61 | 588 
Max | na 
9] 
na 
na 
2-6 
Min 
60 «= «(C&D 
2-6 
Barra do Corda......... 
Max 
. 
Vi 
9] 
9-1] 
Min 
oo. 
= 
9-11 
Belo Horizonte......... 
Max 
8] 
8i 
80. 
-| 
18-21 
Min 
18-21 
Ce 
a a 
Max 
| 
9-11 
| 
Min 
| 
<a 
9-11 
owe ewes 
Max 
| 
12-20 
~ | Min 
12-20 
Cee os 
Max | 88 
91] 
] 
Min 
] 
Max | 87 
| 
17-19 
| 
Min 
oe. 
17-19 
Max 
8] 
6-8 
71. 
6-8 
ba e8 ina 
Max 
82. 
9-14 
? 
| 
Min 
oS: 
9-14 
Min 
| 
ae 
50. 
Max} 
na 
88 | na 
2-3 
Min 
| 
na 
na 
ae 
na 
2-3 
Curvelo....<.-. 
Max | 85 — 87 
8] 
Qi 
Min 
54. 
63 | 
10. 
\ametOhS oe 
Max 
3-5 
Min 
3-5 
«nando de Noronha...} 
Max| 
£82 
82 | 16-19 
Min 
16-19 
‘orianépolis....°...... 
Max 
17-19 
Min 
os. 
6... 
17-19 
i 
ag 
Max 
RS 
a 
Max 
Min 
Max | 82 
8-12 
Min 
8-12 
Guarabira... 
Max 
=—ss«&@9)] 
& 
| 
Min 
Guaramiranga.......... 
Max 
10-12 
Min 
10-12 
Guarapuava............ 
Max | 79 
73 | 11-14 
Min 
. 
| 
11-14 
EEL 
NTE 
Max] 
8-10 
Min 
72:---+99 
8-10 
Max | 87 
#86 
17-20 
Min 
| Ee 
8 | 
17-20 
NE ren 
Max | 87 
Min 
os 6. GSS 
Max | 90 
Min 
Max] 
80 | 17-19 
Min 
17-19 
Max | 91 
Min 
PAGE 23-25 
+e 
Ge 
Se} 
Be 
t 
| 
i 
-
‘BTATION 
JAN | FEB | MAR | apr | May | sun | yuu | ava! sep | ocr | Nov| pec] 
ANN | YRS REC 
Max 
Min 
DU. ore 
OR 
Max | 85 
~=—s«B 
Min 
Max | 86 
 & 
12-16 
JOnO TUMOR... 
os ook 
Max | 87 
Min 
3. 
9h 
m 
RS oo 
ae 
Max | 87 
8] 
2-6 
Min 
2-6 
I 
Max | 87 
18-19 
| 
Min 
7] 
18-19 
Nazaré da Mata........ 
Max 
9-10 
| 
Nir 
9-10 
ae 
as 
ieee 
i3 
9-13 
Mi. 
9-13 
en 
6s eG 
Max 
Min 
61. 
Pe eo 
Max 
| 
913 
Min 
9-13 
Pérto Alegre............| Max 
|]. 
7) 
j 
Min | 68 
rors Baer... 
SS: 
Max | 84 
2-3 
Min 
2-3 
SEES 
here rete 
sete Max | 92 
9] 
9} 
2-5 
Min 
70, 
na 
Go 
a 
na 
2-5 
Quixeramobim.......... 
Max | 92 
&8 
90 | 26-28 
Min 
75 | 26-28 
ga 
ee 
Max | 86 
8] 
4-9 
Min 
4-9 
Rio de Janeiro... ..... 
Max 
| 
38—40 
Min 
66. 
68 | 38-40 
mee treeees. 2... 
Max 
Min 
6] 
oi Si 
Max | 87 
1] 
Min 
Min 
Sante Rosa.......... 
Max |] 91 
te 
- 7% 
| 
Min 
Santa Vitéria do Palmar.}| 
Max 
| 
8] 
Min 
SS 
Se 
ee 
aes 
Max | 86 
Min 
MN GINNING 
oR eee 
Max | 82 
8] 
| 
14-18 
| 
Min 
5] 
oS... 
14-18 
Max 
8&6 
Min 
oa 
Max 
67. 
. 
Min 
-~. 
eae 
Teal Ov = 
Max | 86 
14-17 
Min 
14-17 
NN i 
ee 
Max 
9] 
2-8 
Min 
ee 
2-8 
RN Se 
oe 
Max | 83 
9-12 
Min 
566 
9-12 
Urussanga........ 
Max/|/na 
na 
na 
na 
ona 
na 
na 
Min 
na 
TETRA 
ERE TS Max 
| 
: 
Min 
I ore 
lhe sc gy Max | 82 
3-8 
Min 
3-8 
NIS 
94-I1 
FIGURE 23-24 (Continued) 
AIR FORCE 
OCTOBER 1954 
na 
Data not available. 
* 
Near but outside the 94-I Area. 
PAGE 23-26 
‘ 
if 
y! 
f 
w 
-
AIR FORCE 
—- OCTOBER 1954 
MILITARY 
GEOGRAPHY 
Figure 23-25. ABSOLUTE MAXIMUM (OBSERVATIONS AT 1400 LST) AND MINIMUM 
(OBSERVATIONS AT 0700 LST) TEMPERATURES (°F.) 
— 
a 
- 
Pe... 
BTATION 
jaN | FEB | MaR| aPR | May | sun | gut | ava | sep | ocr | Nov | 
| ANN | yRs REC 
Ra oS 
Max | 89 
| 
Min 
a. 
o.oo 
| 106 
104 = 111 
Min | 44 
33.—Cti‘é‘SS 
Barra do Corda......... 
Max 
~~ 
te: 
Gelh6hUM:.lUC 
UN 
103 
5-8 
Min | 66 
5-8 
Belo Horizonte......... 
Max | 95 
ee 
eee, 
Min | 58 
= 
{| Deere 
ee 
Max | 95 
: 
Min | 59 
EL, Fel 
e S Max | 94 
| 
J 
: 
Min 
#69 
l 
Ee 
he ee Max | 100 
102 | 102 
Min | 63 
46... 
—68 
Max 
Min | 60 
Caxias do Sul...........] 
Max | 96 
Min } 41 
sl 
COU 
Min | 52 
55. 
Fernando de Noronha...| 
Max | 86 
: 
, 
Min 
68. 
Florianépolis........... 
Max | 93 
ae 
e 
91 | na 
Min 
Fortalesa.........:. 
Max | 91 
Min 
a 
Max | 92 
Min | 52 
4] 
33° 
Max] 
101 
104 
104 
na 
a 
i 
Min | 67 
Guaramirr. 
: 
Max | 87 
Yu 
Min | 60 
NS 
a 
oe 
Max | 93 
91 | 93 
Min | 46 
BN oe 
oe 
ee 
Max | 99 
100 
102 
100 | 102 
Min 
67 | na 
Eee 
ee 
ae Max | 101 
91 | 101 
Min 
| 
Data not available 
PN ae 
Max | 95 
103 
98 | 103 
Min | 66 
‘61 
Max 
{105 
104 
104 
101 
102 
106 
106 
Min | 42 
Max | 107 
104 
104 
. 
{* 
Min | 47 
. 
DEG ae 
Max | 69 
Min | 40 
PIA rire 
Max | 91 
Min | 65 
a‘. 
PAGE 23-27 
| 
| 
|
NIS 
94-1] 
FIGURE 23-25 (Continued) 
AIR FORCE — OCTOBER 1954 
STATION 
san_| FEB | MAR | apr | may | sun | sur | ava | sep | ocr | Nov | DEC 
ANN | YRS REC 
Max | 98 
100 
102 
We. 
Wi 
| 
Min 
53. 
PR | eee 
Max 
Min 
~=6.66 
63. 
We 
er ee 
Max | 89 
9] 
o::°hCt(cCé 
“| 
Min 
Nazaré da Mata........ 
Max | 96 
Min 
Pe 66 
ee 
Max | 95 
Min 
. 
ee 2 
4] 
el Neer 
Max 
| 
9] 
Min 
| RIAs Ratnam ar ae 
Max | 100 
102 
102 
» 
| Min 
PIG eis 
ei cc es Max | 96 
100 
100 
#100 
100 
Min 
Porto Alegre..:...... 
Max | 105 
105 
102 
ve 
. 
100. 
106 
105 
Min 
25. 
Quixeramobim.......... 
Max | 99 
Min 
= 69 
Rio de Janeiro. 
........ 
Max | 102 
9] 
100 
102 
100 ~= = 102 
102 
Min 
Rie Grane. 
« «icc evince Max | 106 
100 
98 | 106 
Min 
NS SES LEONE ADOT 
Max 
1] 
| 
Min 
=: 68 
Max |} 106 
104 
103 °&100 
9) 
41° 
104 
106 
106 
| 
Min 
:.. 
Banta 
Max | 103 
103 
103 
100 
104 
104 
Min 
| 
29: 
4] 
Santa V.tér:a do Palmar.| 
Max | 106 
107 ~~ 102 
100 | 107 
Miz 
ME 
Max | 102 
100 
#101 
8] 
100 
102 
‘ 
| 
Min 
20... 3) 
Max | 93 
9] 
&&6 
Min 
oe 
Max | 90 
9] 
9] 
9] 
9] 
9] 
Min 
aa 
ee 
ete 
Max | 93 
. 
Min 
4... 
Tedfilo ()toni.......... .| 
Max | 93 
) 
Min 
i eet | 
Max | 94 
#96 
100 
100 
Min 
ee ee 
Max |] 91 
Min 
ES 
ERO 
et ner 
Max | 95 
9] 
Min 
| 
30° 
$2 
na 
Data not available. 
* 
Near but outside 94—-I Area. 
PAGE 23-28 
| 
| 
‘ 
J 
¢ 
¥ 
>
— 
AiR ForcE — OCTOBER 1954 
MILITARY 
GEOGRAPHY 
Figure 23-26. 
DAILY RELATIVE HUMIDITY (%) 
ATION 
yan | FEB | MaR| apr | may | gun | 
| ava | sep | ocr! Nov | 
YRS REC 
80. 
686 
RRS 
raaeat roetnarars 
1] 
SS ok 
cb 
ee ices 
. 
Fernando de Noronha........| 
865 
FlorianGpolie.... 
7... 00.56. 
-Franca..... 
SS 
ee 
Guaramiranga... 
ere. 
se 
NS. of 
3... 
ee 
Oo Foe 
ee 
MN 
6 ee 
ee 
Jaboat&o................. ..| 
«=«._: 87 
: 
a 
ee 
86 - 
na 
na 
ES 
ee eat ear 
= 
Paseo Fundo........... 
&2 
a 
ee 
oe 
8] 
=§ «63 
DS 
a 
na 
eiperamemm............. 
«74 
SR 
ee 
8] 
81. 
SSS 
EEE LL EEE 
1] 
Santa Maria........ Sue a 
San.a Vitéria do Palmar...... 
woes 
ee 
wale 
7s. 
pS ee a 
a 
74: . oe 
* 
Near but outside 94-I Area. 
FiaurE 23-27. MEAN DAILY SURFACE WIND VELOCITY (KNOTS) 
STATION 
gan | rep | man | apr | May | gun | 
| ava | ser | ocr | Nov | pec | 
| YRSREC 
Fernando de Noronha........ 
10.3. 
16.8. 
24.0. 
13.8 
13.4. 
13.61. 
-13.4 
* 
Near but outside 94-I Area. 
PAGE 23-29 
‘
FieuRE 23-28. PREVAIL‘NG DIRECTION OF SURFACE WIND (SUMMATION OF 0700, 14900. AND 2100 
LST OBSERVATIONS) 
AIR ForcE — OCTOBER 1954 
STATION 
san | 
| Mar | apr | may! aun | sun | sve | ser | 
| nov | vec | ann” 
Rec 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
2-4 
SE 
S8E 
S8E 
S8E 
NE 
NE 
NE 
NE 
S8E_ 
S8E 
§8E_ 
SE 
SE 
Barra..:.... 
N 
N 
N 
N 
Ss 
Ge 
t& 
& 
N 
N 
N 
GO 
.. 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
2-3 
os 
$$NE 
NE 
NE 
SE 
NE 
NE 
NE 
8E: 
NE 
NE 
NS 
NE 
-NE 
NE 
NE: 
NE 
NE 
.NE. 
NE 
NE 
SE. 
SE 
SE 
SE 
.8E 
SE: 
SE. 
8E- 
8E 
SE 
N 
N 
N 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
9-11 
Car velas 
NE 
NE 
C 
NE 
NW 
C 
C 
C 
N 
NE 
NE 
NE 
NE. 
6-8 
oho 
roe 
C 
C 
8E 
C 
E 
E 
E 
E 
E 
E 
C 
E 
E 
SE 
SE 
SE 
SE 
NW 
NW 
NW 
NW 
SBE_ 
SE _ SE 
_S8E 
SE 
SW 
SW 
SE 
SE 
§8W 
SE 
NE. 
&E 
SE 
Fernando de Noronha......._. 
E 
E 
E 
E 
§ 
E 
E 
E 
E 
E 
Florianépolis..:........: oes 
N 
§ 
§ 
S 
Garanhuns................. 
E 
E 
SE 
NE 
E 
NE 
E 
E 
E 
NE 
SE 
5E 
E 
SE 
SE 
S8E 
SE 
S8E 
SE 
SE 
SE 
-8E 
S8E 
8E 
SE 
is 
C 
E 
E 
E 
E 
E 
E 
E 
E 
E 
6-9 
Ilhéus...... 
NE 
NE 
E 
E 
GW. 
NE 
NE 
NE 
E 
INR 6 
ee 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
> & 
SE 
SBE 
SE 
NW | BE 
C 
C 
SE 
C 
C 
C 
C 
C 
C 
6-9 
E 
E 
E 
> 
E 
E 
E 
E 
E 
SS 
cc 
Oe 
ee 
NW 
NW 
NW 
N 
W 
NW 
W 
NW 
NW 
NW 
NW 
NW 
NW 
Se 
. BE. 
SE... 
BE 
SE 
8E.S8E 
8E 
8E 
SE 
eee 
E 
E 
E 
E 
E 
E 
E 
E 
E 
=: 
fs 
E 
E 
TS 0 
C 
C 
C 
C 
C. 
C 
C 
C 
C 
C 
C 
C 
C 
ee 
NE 
E 
E 
C 
C 
ea 
E 
E 
E 
NE 
NE 
E 
2-6 
NE. 
NE 
NE 
NE 
C 
C 
C 
NE 
NE 
NE 
NE 
NE 
6-10 
NE 
NE 
NE 
NE 
NE 
NE 
NE 
NE 
NE 
NE 
NE 
NE 
NE 
N 
N 
N 
NE 
8W 
N 
NW 
N 
NE 
NE 
N 
E 
ESE 
ESE 
E 
E 
W 
WwW 
E 
ESE 
ESE 
ESE 
ESE| 
ESE 
Propri4....... 
E 
E 
E 
SE 
SE 
8E 
E 
E 
E 
E 
E 
2-4 
.NE 
NE 
8E 
8E 
8E.8E.8E. 
NE 
NE 
NE 
NE 
NE 
N 
N 
N 
N 
N 
N 
N 
N 
C 
C 
C 
C 
N 
Rio 
... 
NE 
NE 
NE 
NE 
NE. 
NE 
NE 
NE 
NE 
.NE 
NE 
NE 
i 
E 
E 
E 
E 
E 
E 
E 
E 
E 
E 
E 
E 
E 
SN 
ee as 
N 
N 
N 
NE 
NE 
NE 
NE 
WE 
NE 
NE. 
NE 
NE 
NE 
NE 
-NE 
NE 
&-9 
B&o Luis 
C 
C 
C° 
C 
C 
NE 
NE 
NE 
NE 
NE 
NE 
NE 
NE 
2-4 
SBE 
C 
C 
C 
C 
C 
St 
--8E 
C 
2-6 
000 
SESE" 
BE" 
BE 
BE" 
BEE 
NE 
NE 
8E 
SE 
6-8 
C 
C 
C 
C 
E 
E 
E 
NE 
C 
os 
ae 
C 
C 
C 
C. 
C 
C 
C 
C 
RS 
ae C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
C 
3-7 
na 
Data not available. 
* 
Near but outside 94-I Area. 
& he 
Pacr 23-30 
| 
} 
; 
| 
el 
PA 
-
LIST OF STATIONS 
é 
LATI- 
LONGI- | ELEVA- 
LATI- 
LONGI- 
|ELEVA- 
TUDE* 
TUDE* 
TION 
' TUDE* 
TUDE* 
TION 
18 38 
48 11 
3.036 
7 06 
34 52 
177 
28 56 
49.29 
na 
35 44 
151 
11 05 
43 09 
1,339 
7 44 
35 15 
271 
5 30 
45 15 
267 
26 28 
51 58 
3,643 
22 53 
8 06 
39 34 
163 
14 04 
42 29 
28 15 
52 24 
1,995 
2 54 
40 50 
31 45 
52 21 
21 45 
41 18 
17 21 
44 56 
1,650 
17 42 
39 09 
30 O1 
Si is 
18 10 
47 57 
2,805 
16 26 
39 05 
na 
10 09 
36 11 
5 16 
39 15 
259 
Curvele...... 
18 45 
44 25 
8 04 
34 48 
18 15 
43 36 
4,147 
SON 
Z2 28 
44 28 
1,424 
Fernando de Noronha........... 
3 51 
32 25 
137 
22 54 
43 14 
27 35 
48 34 
115 
52 05 
3 43 
38 30 
12 59 
38 31 
25 33 
54 38 
509 
29 41 
53 4 
466 
20 32 
47 24 
3,399 
54 27 
1,181 
8 54 
36 31 
2,782 
Santa Vitoria do Palmar........ 
33 31 
53 21 
6 48 
35 28 
330 
SEE 
54 53 
1,398 
25 23 
51 27 
3,635 
47 54 
2,805 
Iguatu..... 
621 | 39 18 
17 51 
41 30 | 1,083 
12 10 
39 45 
23 58 | 4852 | 2,228 || 
8 07 
34 59 
165 
26 53 
52 23 
na 
na 
Data not available. 
* 
** 
Near but outside NIS 94-I Area. 
Coordinates give locations of weather stations and do not correspond necessarily to those for populated places. 
a 
P
é 
( 
\ 
Ke 
Paracatu 
- 
Pl; 
/ 
- 
\ 
\ 
\ 
} 
\ 
\ 
\ 
Grande 
~~ UBERABA 
| 
| 
\ 
| 
Aquidauana 
Grande 
residente Epitacio 
| 
Apucarana 
| 
.Sorocaba 
ULO Santo 
Santos 
| 
| 
| 
* Ponta Grossa 
\ 
A 
z do Iguacu 
RO lou 
bd 
CURITIBA 
FOZ DO IGUACY 
[GUARAPUAVA 
| } 
XANKERE 
Blumeneu 
| 
» 
i} nites 
; 
FL 
PSANTA ROSA 
FLO \ANOPOLIS 
SANTIAGO 
/ 
aria 
/ 
ad 
\ 
PORTO 
| 
28°52! 
/ 
2. 
ILHAS MARTIM VAZ ) 
20° 
/ 
be 
2 Miles 
2 Kilometers 
a 
4s 
i 
| 
| 
Concepcion 
Paysandi 
29°20’ 
Gualeguaycné 
gio 
{ 
/ 
\ 
GUA, 
f 
The transportation shown on this map is 
ty 
generalized end ber orientation purposes only 
Minas 
Rocha 
Boundories are not necessarily those 
recognized by the U.S. Government, 
Kilometers 
|
| 
\ 
RAY 
porat 
| 
OWindpolis 
| 
ISLAND POSSESSIONS OF 
Ponte 
| 
ARGENTIN 
a 
| 
33°50/ 
33°48’ 
32°24’ 
de Fora 
Sdo Jodo da Narra 
/ 
ATOL DAS ROCAS 
CABO DE SAO | 
Tome 
OF JAN 
| 
| 
CS 
£_Kilometers 
QIMETA 
RASA 
32°28/ 
32°26’ 
3°50’ 
My 
24) 
| FERNANDO DE 
NOO OE 
STATION LOCATIONS 
METEOROLOGICAL STATION 
| 
28°50/ 
Locations are shown only for stations for 
which data are presented in text or tables 
GENERAL BASIC INFORMATION 
HA DO} SUL 
- 
Internal administrative boundary 
® 
National capital 
29°18" 
MACE!O 
internal administrative capital 
NDADE 
Selected railroad 
Selected road 
em Intermittent stream 
{ 
100 
200 
300 
400 
500 
/ 
Statute Miles 
200 
300 
400 
500 
Kilometers 
GPO—SSO 
STATION LOCATIONS 
FiGURE 23-29 
) 
> 
/ 
/ 
A 
> 
h 
- 
4 ~ T
wis 94-1 
a4 
| 
od 
/ 
\ 
FORTALEZA 
Tucurui 
rh 
Ay 
FOR TAL EZA 
N 
/ 
J 
GUARAMIRANGA 
f 
| 
| 
Oeiras® 
f 
Cajazeiras 
Patos 
\ 
< 
y 
} 
- 
f 
— 
Paulistana 
a 
Pesqueira 
Pedro Afonso 
awh 
~ 
Garanhune@” 
( 
Senhor do Bonfim ¢ 
\ 
\ 
f 
Natividade 
*Peixe 
‘ 
wo
| 
| 
- 
/ 
| 
CAE 
LOSSARY 
> 
bata 
int 
cape, 
porn 
¢ 
» 
cabo 
-- 
_ 
island 
Jf 
f 
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WEATHER AND CLIMATE 
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AIR FORCE — DECEMBER 1954 
Nis 
94- i] 
TABLE OF CONTENTS FOR SECTION 23 
Page 
A. General weather and climatic conditions 
. 
23- 
1. Introduction 
23- 
2. Synoptic aspects of the climate . 
23- 2 
a. Climatic seasons 
23- 2 
b. Year-to-year variation in precipitation . 
n° 
c. Migratory cyclones and anticyclones 
. 
23- 3 
d. Air masses 
23- 3 
e. Effect of topography . 
23- 3 
3. Weather and military operations . 
23- 4 
1. Air operations | 
; 
23- 4 
a. Individual climatic factors . 
23- 4 
(1) Cloudiness 
. 
23- 4 
(3) Aircraft icing and upper-air temperatures. 
..... 
. 
23- 7 
(4) Winds aloft. 
23- 8 
b. Combinations of climatic ieciore 
23- 8 
2. Air-ground operations 
23- 8 
a. Individual climatic factors 
. 
23- 8 
(1) Low cloudiness 
aa- 8 
(2) Visibility . 
23- 9 
(3) Turbulence . 
23- 9 
b. Combinations of climatic eles 
23 - 10 
3. Ground surface operations . 
23-11 
a. Individual climatic factors 
. 
23-11 
(1) Precipitation 
23 - 11 
(2) Temperature and relative humidity 
23 - 11 
(3) Surface winds . 
23 - 14 
(4) Visibility . 
23 - 17 
(5) Flood conditions . 
b. Overall effect of surface 
on 
age, and shelter . 
23-17 
(1) Clothing . 
23-17 
(2) Storage 
. 
23-18 
(3) Shelter 
23-18 
4. Amphibious operations 
. 
23 - 18 
a. Wet season 
23 - 18 
b. Dry season 
23 - 19 
C. Meteorological facilities and organization 
23 - 19 
1. Organization . 
23 - 19 
2. Operation 
. 
23 - 20 
D. Climatic data tables 
. 
. 
23 - 20 
E. Comments on principal sources 
. 
33 - 26 
_ 
PAGE 23-i 
|
LIST OF FIGURES 
| 
Page 
Fig. 23-1 
Map 
Precipitation and airflow, February 
23- 2 
Fig. 23-2 
Map 
Precipitation and airflow, August 
23- 2 
Fig. 23-3 
Map 
Annual number of cloudy days 
23- 5 
Fig. 23-4 
Map 
Annual number of clear days 
23- 
Fig. 23-5 
| 
Map 
Seasonal variation in clear days 
23- 6 
Fig. 23-6 
Map 
Days with thunderstorms 
_ 
23- 7 
Fig. 23-7 
Diag. 
Days with visibility <3 miles at Belém 
23- 9 
Fig. 23-8 
Map 
Days with fog 
23 - 10 
Fig. 23-9 
Map / 
Mean monthly precipitation 
23-12 
Fig. 23-10 
Map 
Days with precipitation 50.01 inch 
23 - 13 
Fig. 23-11 
Map 
Lowest observed temperature 
23 - 14 
Fig. 23-12 
Map 
Daily temperature variation 
23-15 
Fig. 23-13 
Map 
Mean relative humidity 
23 - 16 
Fig. 23-14 
Table 
Clothing requirements 
23 - 18 
Fig. 23-15 
Table 
Mean precipitation 
23 - 21 
Fig. 23-16 
Table 
Highest, lowest, and mean annual precipita- 
23 - 22 
| 
tion 
Fig. 23-17 
Table 
Number of cloudy days. 
23 - 22 
Fig. 23-18 
Table 
Number of clear days 
| 
23 - 23 
Fig. 23-19 
Table 
Days with total cloud cover =2-tenths at 
23 - 23 
specified hours 
Fig. 23-20 
Table 
Days with thunderstorms 
23 - 24 
Fig. 23-21 
Table 
Maximum 24-hour precipitation 
23 - 24 
Fig. 23-22 
Table 
Days with precipitation =0.01 inch 
23 - 25 
Fig. 23-23 
Table 
Absolute maximum and minimum tempera- 
23 - 26 
tures 
Fig. 23-24 
Table 
Mean daily maximum and minimum tem- 
23-27 
| 
peratures 
Fig. 23-25 
Table 
Days with calm 0900 LST 
| 
23 - 28 
Fig. 25--26 
Map 
Station Locations 
follows 23 - 28 
This Section was prepared for the NIS under the general 
supervision of the Directorate of Intelligence, USAF, by the 
Air Force/Air Weather Service in coordination with the Joint 
Meteorological Committee. 
Material on amphibious opera- 
tions was prepared by the Office of Naval Intelligence and 
material on clothing, storage, and temporary shelter by the 
Office of the Quartermaster General. 
PAGE 23-ii 
‘ 
‘ 
( 
‘ 
-
AIR FORCE — DECEMBER 1954 
MILITARY GEOGRAPHY 
23. 
Weather and Climate 
A. 
General weather and climatic conditions 
1. Introduction 
The NIS 94-II Area lies almost wholly within the 
Tropics. 
Pronounced day-to-day and season-to- 
season changes which characterize the temperate 
latitudes are absent. 
Cooler air from the South 
Temperate Zone occasionally reaches Northwest 
Brazil in winter. 
Such outbursts of cool air are 
infrequent, however, and are not pronounced when 
compared to those affecting North America. 
A comparison of conditions resulting from the 
location of the tropical portion of Mexico, in the 
Northern Hemisphere, and that of Northwest 
Brazil, almost entirely in the Southern Hemi- 
sphere, explains 
this difference 
in the winter 
weather patterns. 
J .e huge land mass of North 
America extends n 
chward from Mexico into the 
polar regions, or ’, ,roximately to 70°N. 
Cold air 
periodically flo... 
across this land mass 
ii winter. 
‘ui. 
(4. not all of these outbreaks 
reach the .; 
, there are an appreciable num- 
ber of occasions when the polar air does reach 
Mexico, bringing showers and cooler weather. 
In contrast, the continent of South America nar- 
rows toward the Antarctic and terminates at about 
55°S. 
In its passage over the open sea, the cold — 
air from the Antarctic is warmed to a temperature 
generally above 32° F. before it reaches the tip of 
South America. 
The air continues to flow north- — 
ward and undergoes further modification as it 
moves across the relatively narrow land mass of 
Argentina. 
These factors tend to limit severely 
the number of occasions when cool air is able to 
penetrate 
the tropical 
lowlands 
of Northwest 
Brazil. 
| 
While the comparison just cited is limited to the 
northern and southern winters, another compari- 
son pertains to the northern and southern sum- 
mers. 
Both Mexico and Northwest Brazil have 
Summer 
rainy seasons. 
The 
rainy season 
of 
Nore 
Requests for solutions to specific problems in- 
volving the interpretation of tlre weather factor 
in the user’s unique operational terms should be 
directed to the Commander, Air Weather Service, 
MATS, USAF, Washington 25, D. C. 
- Mexico generally reaches 
a maximum about Au- 
gust, and that of interior Northwest Brazil, about 
February. 
The summer maximum in each area 
results from the intrusion of warm, moist air from 
the Atlantic. 
During summer in the Northern 
Hemisphere, moist tropical air flows toward lower 
pressure over Mexico and brings copious rainfall. 
During the Brazilian summer, lower pressure de- 
velops over Northwest Brazil. 
In response to this 
pressure gradient the moist trade winds approach- 
ing the northeast coast are induced to flow far 
into the interior. 
The moist air becomes unstable 
over the heated land, and frequent showers and 
thunderstorms occur. 
The role of the trade winds decreases in both 
areas 
during 
their respective 
winters. 
Higher 
pressures build up over the interiors and the flow 
of moist air gradually diminishes. 
An additional 
climatic control tends to further decrease the 
amount »f rainfall received in interior Northwest 
Brazil in winter. 
The mountains and highlands 
located in southeastern Brazil impede the low-level 
flow of moist oceanic air which is directed toward 
Northwest Brazil from the southeast. 
- 
In summer, similar shielding effects are afforded 
by the mountains north of the Amazon Basin. 
From December through February when the north- 
east trade winds prevail and most of Northwest 
Brazil is experiencing rainy weather, the regions 
shielded 
by the Guiana Highlands experience a dis- 
| 
tinct dry season. 
| 
FIGURE 23-1 shows the mean monthly precipita- 
tion in February, when the flow of moist air from 
the 
tropical 
Atlantic 
is well 
developed. 
The 
shielding effect of the mountains in British Guiana 
is well illustrated at Boa Vista, in north-central 
Brazil, where the average February precipitation 
is only 1.3 inches. 
The mean precipitation during August, when 
the predominant airflow is from the southeast, is 
illustrated in Ficure 23-2. 
Immediately west of 
the highlands of eastern Brazil, precipitation is 
light. 
The air picks up moisture as it drifts north- 
westward across the Amazon Basin, and rainfall 
amounts increase over the northern and western 
portions of Brazil. 
OPpY 
SANITIZED COrL 
23-1 
Content UNCLASSIFIED 
| 
| 
—
$0 
FEBRUARY 
more. 
FIGURE 23-2. MEAN PRECIPITATION 
(INCHES) 
AND AIRFLOW, 
AUGUST 
2. Synoptic aspects of the climate 
a. CLIMATIC SEASONS — There are certain sea- 
sonal changes in the climate of this NIS Geo- 
praphic Area. 
Because of the scarcity of other 
types of data, the following discussion of seasonal 
trends is based on rainfall and temperature data. 
Over the southern portion of Northwest Brazil, 
the rainy season begins in late spring and extends 
through summer into early fall. 
In winter, or 
23-2 
more exactly from May through September, pre- 
cipitation is very light. 
Progressing northward across the Amazon Ba- 
sin, the rainy season sets in at an increasingly 
later date. 
Along the 6°S. parallel, the rainy 
season generally reaches its peak in February or 
March. 
Farther north, March through April are 
the rainiest months, while at Boa Vista, one of the 
northernmost precipitation stations, 
June marks 
the midpoint of the rainy season. 
| 
As can be seen from the tabular data in FIGuRE 
23-15, the dry season is well marked at many 
points in this Area. 
Of the 57 stations listed, 25 
have months in which the average precipitation is 
1 inch or less. 
At most of these 25 points, this 
low average is maintained for 3 consecutive months. 
The data show also that at a majority of the 
stations the wet season is pronounced. 
For ex- 
ample, 47 of the 57 selected stations have at least 
1 month with an average rainfall of 10 inches or 
At Benjamin Constant, in extreme western 
Brazil, there are 8 months with an average of 19 
inches or more. 
At a majority of the stations, 
however, there are 3 to 5 such months during the 
year. 
The 
decrease 
in precipitation 
is often 
abrupt. 
At Formosa and Goias, in the southeast 
portion of this Area, precipitation decreases sharply 
from April to May. 
| 
Seasonal changes in temperature are not as dis- 
tinct as those for precipitation. 
This is true par- 
ticularly over the Amazon Basin, where the aver- 
age maximum temperature vaiies from a little 
above 90° F. in June through November to a little 
below 90° F. from December through May. 
The 
Slightly higher temperature in winter results from 
the lighter rainfall and minimum cloudiness of 
winter. 
The minimum 
temperature 
varies 
be- 
tween 70° and 75° F. during the year. 
Over the southern portion of the Area the sea- 
sonal variation in temperature is more pronounced. 
Average maximum temperatures vary from about 
90° F. in summer to 80° F. in winter, while the 
minimum temperatures va. 
’ from 70° F. to some- 
what less than 60° F. 
Duri. ¢ outbreaks of cold 
air from the south, freezing 
-..eratures, although 
rare, are occasionally experienced in the south. 
b. YEAR-TO-YEAR VARIATION IN PRECIPITATION — 
Many of the stations show a marked variation in 
annual precipitation from year to year. 
FiGuRE 
23-16 gives tabularly the highest, lowest, and 
mean annual amounts received during a 25-year 
period. 
Those places that receive relatively large 
amounts 
(over 80 inches) 
annually rarely ex- 
perience a drought. 
However, those with annual 
averages close to 50 inches or less occasionally re- 
ceive only half that amount. 
| 
yet 
| 
| 
bow 
199 
“ 
| 
pos 
| 
| 
yuo 
ong 
| 
| 
| 
110 
\ 
| 
ie 
| 
\ 
| 
| 
\ 
| 
| 
/ 
| 
FIGURE 
23-1. MEAN PRECIPITATION 
(INCHES) 
AND AIRFLOW, 
| 
| 
TAY 
Indy 
| 
fe 
¥ as 
| 
og 
| 
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OF, i 
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| 
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yp q7 
| 
| 
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| 
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| 
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| 
| 
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AtrR ForRcE — DECEMBER 1954 
Rainfall amounts for a given month also vary 
significantly from year to year. 
For example, at 
Cuiaba in March the average is 8 inches but as 
little as 2 inches and as much as 15 inches have 
been recorded. 
Although the average for June at 
Pérto Velho is 1.4 inches, as much as 4.0 inches 
and as little as 0.1 inch are reported: 
Similar 
variations have occurred at other stations in the 
Area. 
Cc. MIGRATORY CYCLONES AND ANTICYCLONES — 
Low-pres“ure systems occasionally skirt the ex- 
treme southern portion of 
Northwest Brazil. 
Over 
the major portion, however, only their indirect ef- 
fects are felt. 
The low-pressure centers generally 
make their first appearance over Argentina and 
then travel eastward over the Atlantic Ocean. 
The 
center of higher pressure which normally follows 
the low takes a northward course along the eastern 
coast of South America. 
Ordinarily, the center of 
higher pressure cannot be followed north of Rio 
de Janeiro. 
The indirect effect felt in the Amazon 
Basin consists of a northward flow of cooler, drier 
air. 
Its depth has been measured and on one oc- 
casion reached the 3,f ,0-foot level. 
The advance 
of the leading edge 
the cold air can be followed 
northward. 
Wave 
r secondary low-pressure sys- 
tems rarely form 
..: 
this edge or cold front, but 
showers and th 
-ms are common. 
Over the suuth 
of lows are 1..0r% ulrect and dynamic. 
Warmer air 
from the north flows toward the southern portion 
of the Area as the low develops. 
This flow is in 
turn replaced by one of cooler air from the south 
as the low moves eastward. 
Showers occur along 
the frontal surface between the two air masses. 
The frontal surface marks the leading edge of the 
cold air and is generally oriented northwest to 
— 
southeast. 
Its direction of movement is normally 
toward the northeast. 
| 
The intensity of lows and consequently the 
strength of the opposing air currents vary. 
Oc- 
casionally they are well developed and rain occurs 
over a wide region. 
At such times the rush of 
cooler air northward will carry to the Equator. 
An 
examination of the Brazilian daily weather maps 
indicates that the majority of the lows are weak. 
It is difficult to estimate their frequency, although 
published Brazilian summaries indicate that high- 
pressure centers move across southern Brazil at 
the rate of 4 or 5 per month. 
d. AiR MASSES — Three main air-mass types 
affect Northwest Brazil. 
The first of these con- 
sists of warm, moist air which flows into Brazil 
from the tropical North Atlantic during summer 
when pressures are relatively low over the interior. 
This airstream has had a long trajectory over the 
MILITARY 
GEOGRAPHY 
. portion of the Area the effects 
ocean and is fairly deep. 
The air becomes un- 
stable 
as 
it flows 
across 
the heated 
interior. 
Cumulus clouds form during the late morning, 
frequently 
building 
into 
cumulonimbus 
with 
thunderstorms by afternoon. 
The flow varies from 
weak to pronounced and is sporadic in nature. 
Under the influence of those low-pressure centers 
which cross Argentina, the flow of warm air often 
reaches the southernmost portion of this NIS Geo- 
graphic Area. 
The second air mass is also tropical in nature 
and is present during the winter. 
It has its origin 
in the South Atlantic high-pressure cell, which 
frequently extends into Brazil during the winter. 
The air flows northwestward from this cell across 
the eastern Brazilian Highlands. 
It is warmed as 
it descends the western slopes and arrives over the 
Amazon Basin as fairly warm, dry air. 
Lower 
_ pressures over the Guiana Highlands cause the flow 
to continue northward. 
Over the Amazon Basin 
this relatively shallow air mass is capped by sub- 
siding warm air associated with the high-pressure 
cell. 
Convective activity and shower conditions 
are therefore at a minimum during winter. 
The 
influence of the subsiding warm air does not extend 
to extreme northern Brazil, however; here heavy 
showers are commonplace as the air moves up- 
slope out of the Amazon Basin. 
The third air mass affecting Northwest Brazil is 
composed of cold air which periodically flows to- 
ward the Tropics from the South Temperate Zone. 
These outbreaks of cold air have their greatest 
frequency in winter, when they occasionally bring 
freezing temperatures to the extreme southern 
portion of the Area. 
Their influence decreases 
northward, and only once or twice a year do they 
reach the Equator. 
Showers and thunderstorms accompany the flow 
of cold air as it moves northward. 
If the flow is 
weak, thunderstorm activity is sparse and the de- 
crease 
in temperature 
is moderate. 
In either 
event, the air is less humid for several days after 
the frontal passage. 
The flow of cold air normally 
does not last for more than a day ortwo. 
The stag- 
nating air mass forms rather quickly and gradually 
loses its invigorating quality of dryness. 
e. EFFECT OF TOPOGRAPHY — Three mountain 
systems, the Brazilian Highlands to the southeast, 
the Andes to the west, and the Guiana Highlands 
to the north, affect the climate of Northwest Bra- 
zil. 
There are also three low-level openings to the 
Amazon Basin. 
The first of these is the mouth of 
the Amazon Basin through which Atlantic mari- 
time air enters the lowland interior. 
The second 
opening lies in the south and serves as a pathway 
PAGE 23-3 
-
for cold air to flow from Argentina toward the 
Amazon Basin. 
Through the third opening in 
-the northwest, moist air flows out of the Amazon 
Basin toward the plains of Colombia. 
Of the three mountain systems affecting the cli- 
mate of the NIS 94-II Area, the Brazilian High- 
lands are probably the most significant. 
These 
highlands impede the free exchange of air at low 
levels between the Atlantic Ocean and the interior 
lowlands. 
This role isa secondary one. Of greater 
significance is the fact that, during winter, cooler 
air forms over the plateau and favors the extension 
of the South Atlantic high-pressure cell across the 
Brazilian Highlands. 
From this extended 
cell, 
relatively dry air flows across the Amazon Basin 
during the winter. 
In addition, the warm air 
present at upper levels tends to suppress convec- 
tion and shower activity. 
Asa result, rainfall over 
the highlands and in the Amazon Basin, particu- 
larly the southern portion, is rather light in winter. 
During summer when the sun reaches its southern- 
most position, the warmer temperatures aid the 
- 
establishment of lower pressure over the highlands. 
Moist air from the Amazon is then able to reach 
these highlands. 
Convection is not impeded by 
the presence of a temperature inversion at upper 
levels, and showers or thunderstorms are frequent. 
The Andes Mountains likewise influence the cli- 
| 
mate of Northwest Brazil, although their role is 
less distinct. 
The Territério do Acre, in extreme 
western Brazil, lies on the approaches to the Peru- 
vian Andes. 
The flow of air onto these approaches 
during the northeast monsoon produces heavy 
rains. These rains as well as the heavy rains which 
fall on the Andean slopes of Colombia, Ecuador, 
and Peru feed the tributaries of the Amazon River. 
The southern Andes play a somewhat different — 
role. 
They tend to disrupt the circulation around 
low-pressure centers which approach the coast of 
Chile from the Pacific area. 
These lows normally 
regenerate over northern Argentina and then move 
eastward. 
Cooler air sweeps northward into Brazil 
after the lows move to the Atlantic. 
Were it not 
for the blocking action of the Andes of Chile, 
cooler air from the Pacific would more frequently 
affect southern Brazil. 
Climatic influences attributable to the Guiana 
Highlands are discussed in the introduction to 
this Subsection. 
It was pointed out that, during 
the season of northeast airflow, many points on 
the lee side of these highlands experience distinct 
dry seasons. 
In contrast, during the period of 
‘southeast airflow, many points on the windward 
slopes receive heavy precipitation. 
PaGE 23-4 
B. Weather and military operations 
This Subsection is concerned with the effects of 
the various meteorological 
elements and 
their 
variations upon military operations, which are here 
divided into four broad groups: 
air, air-ground, 
ground surface, and amphibious. 
The discussion 
is not, for the most part, broken down by specific 
operations, but by the meteorological elements as_ 
they affect each group as a whole. 
The meteor- 
ological information 
is, therefore, organized 
to 
highlight conditions that may be considered as fac- 
tors in planning. 
Discussion of the effects of 
weather on specific operations is avoided since the 
weather factor in an operation is subject to change 
with the changing requirement of the operatior 
itself. 
| 
1. Air operations 
a. INDIVIDUAL CLIMATIC FACTORS 
| 
(1) Cloudiness —Cloud 
conditions 
in the 
NIS 94-II Area are frequently favorable for a vari-. 
ety of aerial operations. The level at which a visual 
mission can be carried out depends, to a large ex- 
_ 
tent, on cloud type as well as coverage and height. 
Unlike areas in the temperate latitude , an ex- 
tended overcast in this Area is unusual. 
T' 2 most 
common type of cloudiness is the towerin, cumu- 
lus, which is evidence of instability in 9° air. 
During the afternoon, particularly in sumr __, this 
type 
of 
cloudiness 
frequently 
culmins 
:s 
in 
thunderstorm activity. 
The frequency of cloudy skies varies co:isider- 
ably across Northwest Brazil. 
Ficure 23-3 pre- 
sents in graphic form the mean annual number 
of cloudy days, and Ficure 23-17 gives tabular 
data showing the monthly values. 
Most of the 
| 
stations in the southern portion of the Area have 
100 or more cloudy days annually. 
The average is 
also high in the northwest portion. The frequency 
of cloudy days appears to decrease downstream in 
NoTE 
Air operations are defined as those taking place 
above the frictional influence of che surface ter- 
rain on the atmospheric circulation. 
Some of 
the special operations which may be considered 
in this category are: high-level bombing, aerial 
reconnaissance, and fighter aircraft support and 
interception. 
These operations are largely in- 
fluenced by, or may be subject to, modification 
because of conditions of cloudiness, upper-level 
winds, thunderstorm activity, or ice accretion. 
In most cases, these operations are affected pri- 
marily by upper-air meteorological phenomena. 
In some cases, meteorological conditions on the 
surface may be extremely important. 
Surface 
conditions that are considered in combination 
with upper-air phenomena are treated in this 
Subsection; otherwise they are presented in the 
Subsections on Air-ground and Ground Surface 
Operations. 
| 
| 
- 
\ 
\ 
\ 
\
AtIR FORCE 
— DECEMBER 
1954 
MILITARY 
GEOGRAPHY 
the Amazon Basin, except near the coast where 
averages again become high. FiGurE 23-3 also in- 
dicates that cloud conditions depend, to some de- 
gree, on exposure of the individual station; rather 
large variations in cloud conditions between neigh- 
boring stations are apparent. 
FIGURE 23-4 presents graphically the mean an- 
nual number of clear days, and the monthly fre- 
quencies are given tabularly in Ficure 
23-18. 
Days in this category can be considered favorable 
for visual operations. 
A comparison of FIGURES 
23-3 and 23-4 reveals that over most regions there 
are appreciably fewer clear days than cloudy days. 
The effects of loca 
c« nditions on the number of 
clear 
days 
are 
pz." vnced; 
for example, 
at 
Imperatriz there are 14” clear days annually, while 
at Carolina, not too far to the north, there are 
only 63 such days. 
There is a distinct seasonal trend in cloud con- 
ditions. Minimum cloudiness occurs during win- 
ter, the season of minimum rainfall. 
FIGURE 23-5 
- showing the monthly frequency of clear days high- 
lights this variation at 14 selected points. 
In addition to the seasonal variation, there ex- 
ists a pronounced day-to-day variation in cloudi- 
ness. 
During winter, each outbreak of cooler air 
from the south is attended by an increase in cloudi- 
ness. 
Thunderstorm clouds attend the passage of 
the front followed by a short period of a day or 
two with stratus clouds. 
During the next 2 or 3 
days, clear skies are present, after which there is 
a return to the more familiar cumulus types. 
During summer, bands of cloudy, showery weath- 
er move 
across 
Northwest 
Brazil 
at irregular 
‘ntervals. 
These bands are generally ascribed to 
the presence of the intertropical front or conver- 
gence zone. 
Outside these bands fair-weather cu- 
mulus are predominant. 
There is little information on the daily varia- 
tion in cloud amount. 
Limited data indicate that 
cumulus clouds begin to form in the morning, 
reach a maximum during the afternoon, and tend 
to dissipate 
after sunset. 
Ficure 
23-19 
gives 
tabularly the average number of days with total 
cloud cover equal to or less than 2-tenths at 0900 
and 2100 LST. 
Low stratus clouds occasionally form over the 
tropical forests about the time of sunrise. 
How- 
ever, the cloud layer lifts and then dissipates 
within an hour or two after sunrise. 
Limited ob- 
servations indicate that the stratus layer does not 
form over the rivers along which many of the air- 
fields are located. 
FIGURE 23-3. MEAN ANNUAL NUMBER OF CLOUDY DAYS (CLOUD 
COVER $}8-TENTHS) 
FIGURE 23-4. MEAN ANNUAL NUMBER OF CLEAR DAYS (CLOUD 
COVER =2-TENTHS) 
(2) Thunderstorms and turbulence — Tur- 
bulent air conditions are frequently present over 
this Area during all seasons. 
Cumulus clouds, 
which provide visual evidence of this turbulence, 
range from isolated patches to towering cumulus 
associated with thunderstorms. 
The small patches 
contain moderate turbulence and can be circum- 
navigated. 
Thunderstorms, 
however, 
contain 
areas of extreme turbulence; they too can normally 
PAGE 23-5 
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ANN. AV. 32 DAYS 
PARINTINS 
ANN. Av. 66 DAYS 
JFMAMJJASOND 
JFMAMJJASOND 
ANN. Av.16 DAYS 
/ 
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BELEM 
SAO 
LUIS 
ANN Av. 4 DAYS 
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JFMAMJJASOND 
JFMAMJJASOND . 
CRUZEIRO DO SUL 
ANN AV. 
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ANN. AV. 41 DAYS 
JFMAMJJASOND 
VILHENA 
ANN. AV. 89 
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BARRA DO CORDA 
—110 
ANN. AV. 42 DAYS 
“JFMAMJJASOND 
TERESINA 
JFMAMJJASOND 
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AQUIDAUANA 
ANN. AV. 85 DAYS 
ANN. AV. 75 
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ANN AV. 66 DAYS 
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ANN AV. 115 
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FIGURE 23-5. SEASONAL VARIATION IN CLEAR DAYS (CLOUD COVER =2-TENTHS). 
(For tabular data see Ficure 23-18.) 
be avoided during daylight flight. 
It is more dif- 
ficult to avoid the turbulence at night, although 
the greatest lightning activity generally outlines 
the storm center. 
There is a definite seasonal variation in thunder- 
storm activity. 
The greatest frequency occurs 
from October through April, when moist air from 
the tropical Atlantic flows into the Area. 
FIGURE 
23-6 presents graphically the average number of 
days with thunderstorms at stations within or near 
the Area. 
Similar data are given tabularly in Fic- 
URE 23-20. 
At most stations, June, July, and 
August have 
the 
least number 
of days with 
thunderstorms. 
The influence of the ocean 
is 
evident at Belém, where there are 64 days with 
PAGE 23-6 
thunderstorms annually and substantial activity 
in all months. 
There are very few data available on diurnal 
variations. 
Much of the literature states that 
thunderstorms are more likely to occur during the 
afternoon. 
However, those thunderstorms asso- 
ciated with outbreaks of cold air from the south 
are independent of the time of day, although they 
tend to be more violent in regions where the ar- 
rival of the cold air or cold-frontal passage takes 
place during 
the afternoon 
or early evening. 
Frontal passages are more commonplace in the 
southern portion of the Area. 
At Belém, near the coast, 4 years of hourly ob- 
servations show that the time of greatest thunder- 
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