The Washington times., 1914-05-03

E. H. BOWIE.
the poles. to move much faster than
the earth beneath them. There is
thus a constant movement of the
atmosphere from west to east,
movement which becomes more
marked the nearer one gets to the
poles
OF course, the wind does not al
ways blow from west TO east. Sur
face conditions. such as those enum-
Grated in the daily reports from var
iOuS stations, cause innumerahle
variations and eddies. These are
the winds we feel.
If the high and low pres
sures Travelled an exact course 1t
would be only a problem in simple
arithmetic TO determine when a GER
tain condition would prevail in any
given place. But storms are affect
ed by mountain ranges, by large
bodies of water, by abnormal heat
arising from large stretches of open
country such as prairies or deserts,
by friction with the earth'S sur
face, and by friction of air currents
upon each other so the weather
mans problem becomes a difficult
one because of the number of fac
tors involved.
East Wind Means Storm.
Air from every direction will rush
into a low pressure section. If the
disturbance is toward the west an
easterly wind will be created until
normal conditions prevail. when the
wind again will come from the west.
From this fact arises the seaman's
deep respect for an easterly wind
as a trouble breeder" while he
r-tr,
of clear weather.
To the land lubber an east wind
means rain. Since air is flowing
into an area from every point it
must go somewhere. 1t can only
rise, and as it does that it coOls and
contracts, and in that process the
moisture is condensed and rain fol-
lows.
In the same bulletin is an inter
esting explanation of the relation of
mo sture and temperature to the
weather.
Everyone has noticed that rain
in winter means Warm weather, in
summer cool weather. This arises
from the fact that heat travels more
easily through clear skies than
through clouds and moisture. In
the day time heat reaches the earth
from the sun, at night it leaves the
earth to be absorbed in the at
mosphere.''
In summer, therefore, when the
days are longer than the nights. the
earth is being heated for a greater
part OF the twenty-fOur hours than
IT is being cooled. In consequence
the clearer the weather and the
easier it is for heat to travel, the
hotter ii grows. In winter the re-
verse is true. The cooling time is
longer than the heating, and the
clearer II is the colder il grows"
The forecaster then must look TO
the pressure of the atmosphere as
the key to his weather, and must
calculate all the other conditions
that enter in to effect the course OF
areas OF pressure. He must have
before him reports of conditions in
a wide scope or he only can look
ahead a few hours. The entire map
of the United states is used in the
forecast for thirty-six hours sent
out each morning. and the forecast
FOR fOrty-eight hours, given out
each evening. And in the weekly
forecasts" which only pretend to
he a statement OF general prospects.
the map of the Northern hemisphere
IS employed.
Forecasts Sent Far and Wide.
But making the forecasts is not tine
final step. They must be prepared
for the public For out-of-tOwn
points they are toIeEraphed. For
nearby places they are pointed.
The actual work Of typesctting is
done in a corner Of the same room
where the forecastcr works. Almost
as fast as the predictions are dicta-
ted they are set in type, by the So
called Iogotypc system. which. by
combining letters and phrases uni
formly used in the bulletins. enables
a compOsitor 10 set by hand as fast
as a linotype machine could be oper-
ated.
IT, weather man" which may
be seen hang NJ in pOstotilCeS, also
is prepared IN this room. 4 copper
base with indeHtations TOR various
weather stations IN which a pieco
of type indicating the condition
there is inserted is used in making
up the map. An impression is then
taken. and It is copied and sent
broadcast.
Issuing the tw!ce-a day forecasts
is the routine work Of the bureau.
But the part which gives most diff
hcultv, and which is increasing in
practical usefulness. is tn" Issuance
of special cold wave, frost. storm,
and flood warnings. IT was csti-
mated that. in the severe storm
that swept the Atlantic coast about
six weeks aG", the warnin" brought
back 10 port enough vessels that
would have been carGht
in tn" gale and damaged to pay the
annual appropriation for the bureau
for the years.
The special service is beinr con-
stantly extended. Special bulletins
now are issued for the cotton. corn,
and wheat. sugar, rice. tobacco.
cattle, and fruit regions. Even cram
berry and broom corn growers are
provided SOr.
According to Charles +. Marvin,
chief of the bureau. u constant cf-
fort is be!nc made to improve the
service in respect to forecasts for
longer periods and "A greater per
Centa"" a. accuracy
Make Predictions SPECIFIC.
we ave also working toward mole
specific forecasts. hc said. "Foruirr-
r.. v" raN" q = neral prcdictiuu for
On" section. II is lnuc'I ca cr. Iur
"NaupIr. L. give "a ""n~raI ,rc..ast
for all of New i:uEiHnq th.n 10 ;,r,.-
dict foI each Of tie. S"NrrIl SIHJ,.S