Evening star. [volume] (Washington, D.C.) 1854-1972, 1897-08-28
CYcLONESOF THE SEA
September the Month Of the Most
' Typhoons.
LIKE TIE WEST INDIAN HURRICANE
Description Of These Storms Of the
Pacific.
THEIR PROBABLE CAUSE

THEIR PROBABLE CAUSE
The photographic Office of the Navy De-
partment has computed some highly in
teresting data on the subject of typhoons
and their paths. These typhoons. stories
of the destructive powers of which reach
this country occasionally, are always more
frequent In the coming month than any
month Of the year. The photographic Of
flee calls the attention of mariners in east
Asiatic waters of the Pacific to the fact
that the approaching season marks the
period of maximum frequency of typhoons,
and urges extra precautfon to guard
against the terrible risk of damage and
disaster which almost invariably results
from conflict with one of these storms.
DR.. w. Doberck, director of the Hong Kong
observatory, has prepared table cover
ing the thirteen years from 1888 to 1896,
showing the frequency of these storms and
their monthly distribution. This table.
shows that during that time there was
only one typhoon each in the months of
January and March, none in the month of
February, only four in April and six in
December. For the other months Of the
year the total number Of typhoons of a de-
st, uctive nature were as follows: May, 10;
June. "a; July, As: August. 43; September.
81; October, 81; November, 3d.
Like the West Indian Hurricanes.
The typhoon of the western Pacific ocean
Is in many respects the counterpart OF the
West Indian hurricane of the Atlantic.
Both classes of storms have their origin in
the vicinity of tropical groups of islands.
and under similar barometric conditions;
both undergo the same slow development
and exhibit the same tendency to recurve
upon reaching the northern limit of the
northeast trades
The typhoon, or tropical cyclonic storm of
the Pacific. is due primarily to the appear
ance, generally within the sea inclosed by
the Philippines. the western Carolines and
the Mariana Islands, or within the China
sea, of a local area of low barometer,
brought about by the inequalities in the
temperature conditions of the atmosphere.
In its incipient stages, the deficiency of at
mospheric pressure throughout this area
may be slight, amounting only to a few
hundredths of an inch. Acc ording to vary
ing conditions. such a depression either
may be diSsipated, or 1t may deepen, and
ultimately develop into a well-defined storm
center, giving rise to winds of hurricane
force. At the center, and during the height
of the storm, the barometric pressure may
fall as low as $3.50 inches. The space, how
ever, over which this exceedingly low bar
ometer prevails is generally small, some
times not more than a few miles in extent.
Around this central low. which consti-
tuteS the heart of the storm, the winds cir
culate in a direction contrary to the mo-
ton of the hands of n watch. not in cir
cles, however, but in spirals, which con-
t.nualIy approach the center; the curve
described-by the air being similar in many
respects to the familiar path followed by
the water in escaping from a circular basin
by a central opening in the bottom. To
the north of the storm center We thus
have easterly and northeasterly winds; &c
the south, westerly and SouthweSterly
winds; east of the center, southerly and
i.southeasterly winds will prevail; west of
the center, northerly and northwesterly.
The strength of the wind diminishes as we
go outward, the winds of the typhoon
force rarely extending further than 800
miles frem the storm center - =.
!. If the storm center remained stationary
la vessel hove-to under storm canvas would
no steady shift of the wind. but
would simply feel the force of the gale in
crease until it's full violence was attained.
after which it would gradually blow itself
out. all from one quarter. Such, however,
il never the case. In addition to the move
nient of the air around the storm center,
there is a progressive movement of the
center itself, carrying with it its circulat-
Fling system of Winds In low ATTITUDES the
direction of this motion for all typhoons
has a westerly component, some storms
continuing this course and entering the
mainland of Cochin China; others recurve
toward the northeast and skirt the shores
Of Japan.
Theory of Cyclonic Storms.
The present theory of tropical cyclonic
storms requires that there shall exist at
the center, toward which the incurviug
surface winds are directed, a rising column
Of warm, moist air. Upon reaching the
higher levels of the atmosphere. the water
vapor borne aloft by this air is condensed
into Clouds which are carried by the now
outward curving winds away from the
center on all Sides These clouds. then.
which are formed at great height. and
are of the cirrus type, radiating in long
feathery streamers from the region of the
now ascending column, constitute for the
sailor the best indication of the approach
ing typhcon, sometimes making their ap-
pearance when the storm center is 800
miles distant. AS the center approaches
the density of the cloud canopy deepens,
until the belt of nimbus. from which tor
rents Of rain descend, is attained. The
width Of this belt in front of the center
is in general about $50 miles: in the rear
1t is less.
The first barometric indication of the ap-
proach of a typhoon is the disturbance of
the diurnal range In these low ATTITUDES
a good mercurial barometer. during settled
weather, should show a decided maximum
about 10 am. the reading at that hour
standing between 1886 and 1886 inches
(75S2 to 1907 millimeters). while about p.
m. there should be corresponding mimi
mum, the reading at that hour being about
0. 10 inch (2.5 millimeters) less than 10 a m.
The same thing Is repeated at 10 pm. and
Am. Ii the Afternoon maximum IS appre-
ciably below 29S5 inches or IL the descent
between this and the afternoon minimum
is markedly greater than one-tenth Of an
inch, the weather should be watched with
great care. Several successive days of
light, variably winds and Gains: a period
of hot, sultry weather; increasing moisture
of the atmosphere, shown by the diminish
ing difference between the wet-and-dry-
bulb thermometer; increasing amount of
cloud and an ominous heaving of the sea,
are alT conditions forerunning the occur
renee of a typhoon.
Characteristic typhoon tracks for the
month of August show that these storms
mort hwestward racurva and then ad