The enterprise. [volume] (Wellington, Ohio) 188?-1899, 1891-09-30
WEATHER PREDICTIONS.
The way the Government Ascertains wha
the weather viii be. An Expla-
nation of. Che Maps.

the weather viii be. An Expla-
nation Of. Che Maps. II
The following in regard to the maps is-
sued by the weather bureau is in reply to
letter by Postmaster Hustled to the sig
nal officer at Cleveland, asking him for
my information that would make the
maps more Ineligible to the common
people:
Observations are taken at the same mo-
ment of time = s q. m. end 8 p. m, 10th
time = throughout the United
States, the Canadas and the northwest ter
rltory. Within twenty minutes the obser.
vations are corrected and enciphered and
fled at the telegraph office. As soon as
the reports begin to arrive at q station the
observer on duty deciphers the reports |
and enters the data upon prepared stem
Gil
The dotted circle represents the station;
clear circle represents cloudless wealth
er; the circle with one bar through II
partly cloudy weather; two bars crossing
each other cloudy weather; three bars
crossing each other rain; three bars horri-
zontal TO each other snow. The arrow
shows the direction Of the wind and flies
with 1t. Absence Of arrow denotes calm.
The first set Of figures is the tempera.
ture and the second set the velocity OF
the wind In miles per hour and third set
is entered just to the right whenever a
velocity Of twenty-five miles or higher has
occurred since the preceding observation.
This method Of entering data Is not inva-
riable, as different observers use different
elements, selecting those which will best
subserve public interests, but each map
b.s Its explanatory notes.
These elements above quoted show the
weather conditions actually obtaining al
the moment of observation. In the right
hand margin is given the stations report
ing rainfall and the amount thereof--the
map issued In the morning showing the
amount In the twensyfour hours ending q,
8 a. m. on the date Of issue and the after
noon map showing the amount In the
twelve hours ending al 8 p. m. ~
| The dotted lines crossing the map are
isotherms and connect places hgying the
same temperature and each isotherm L
designated at each extremity. Thus the
dotted line marked at the end 60 degrees
is the isotherm Of 90 degrees Fahrenheit
and signifies that along that line the tenn,
perature Is 90 degrees. Between II and
the isCtherm marked 70 degrees, that the
temperature throughout the region be-
tween the two lines Is between 90 and 70
degrees; and between 90 degrees and 90
degrees that II Is between so and 90 de
grees-the same rule applying throughout
the range of the thermometer.
The solid lines crossing the map are iso
bars and connect places having equal bar
ometric pressure and are drawn for every
tenth Of an inch. All barometer reading
ure reduced to standard Of temperature
80 degrees, and elevation, sea level, I;
make them comparable. Each isobar 4
designated at It's extremity, the figure
there appearing representing the pressur
! the atmosphere exerts upon the earth an,
! its inhabitants and is equal to that whicl
would be exercised by layer Of pur
mercury Of 0 thickness corresponding ;
the number Of inches marked against tn
isobar, Thus, 29.5 indicates that alon
! that line the pressure is equal to that Of
} column Of mercury Of the same height.
5 Storms are divided into two genert
: classes, one in which deficiency In. pref
;. sure occurs, commonly known as "low,
: and another which appears In th
. form Of an area Of excesslv
: pressure and Is called hlgl
Q The wind around low blow SPIRAL
8 into It's center In the direction contrary
0 the hands Of watch, and blow out Iron
r the crest Of high In the direction Of III
Il hands ot watch. Both these classs
s Of storms generally travel across the couI
o try from west To east, but with varying ',
II locities. The low is usually preceded |
d warm weather and rains and the high vii
1t cooler and fair weather; bet these cond
tions are much modified by local pecul
o. critics.
le The shaded red area appearing on
Of morning map signifies that with
Of that area the minimum 1owesD teI
ID peraiure was ten or more degre
ie higher that morning than the preceedin
III and the blue shaded area shows the regi
Of where the temperature has fallen ten
nd erees or more since the preceding moi
en- Ing. The perpendicular black lines Z
Id close the area where rainfall Of one.qua
90 er inch or more has fallen In twentyfo
Dr. hours, ending at a. m. on the date Of
ed sue. On the afternoon map the shad
temperature areas show the change
M maximum (highesD temperature, and I
lat rain area, the amount Of rain in twel
he hours ending at 8 pm.
ith 10 theleft hand margin is given the 70
ty, cast for the state telesraphed from Wa
TO ingtor, below that appearing the force
he for the station and vicinity prepared
ny thr lccql forecast official or obrcryer