New-York tribune., 1919-03-02

indicates TO him his altitude above a.,
level cor the ground. but accurately onlr
when he knows the barometer readjrc :.
sea level COR the ground. AS the aviatoy
ascends the barometer reading decrease,
("falls'D about one inch for each 900 fec.
OF ascent the barometer reading nj 90.
level being about thirty inches But II.
air density is about the only air conditioa
that varies with the same general regular.
lty with the ascent above the ground -.
dlHerent places on the earth's surface. A.
the aviator ascends the sustaining nowor
and the resistance Of the air both do
crease, and at high attitudes his breatbinr
becomes affected
The wind velocity varies irrcgularlv with
the altitude, but usually increases verr
rapidly for the first 500 feet. and then abo,,
two miles per hour 1000 feet above tina,
altitude
The wind direction shifts as the avjato,
rises, usually slightly toward the right q,
the surface directions, but at very high al.
titudes in general eastwardly.
The moisture in the air is yariahle u;.,
the ascent, since it bears close relst;o,
to the temperature. At certain temnsrs.
ture depending on the amount Of jnvis;ho
water vapor in the ar) cloud forms: snd
1t is necessary to know the possible cloud
conditions. since they play very imnor.
tant role in airpane warfare.
The changes in air conditions (excent TO-
air densities) with the ascent above the
ground vary for different localities, espe.
clally for the winds. SO that hiers who hav.
practlsed in one locality have to get accps.
toned to the new conditions at another
place.
The departments of meteorological infor.
nation were maintained in all the contend.
ing forces and became very important stra.
tegic factors. America had its own exnsr,.
on the field for both navy and army. tbs
two helds being quite different in their de.
mands for information
1t was necessary, not only for nlann;nc
aeroplane ofensives but also aeroplane de.
lenslves, to have a day ahead a KNOWLEDGE
OF the air conditions at sea level several
hundred miles TO the west. northwest and
southwest of the flying field. because tbe
cyclones and antcyclones which control
the Atlantic Ocean This necessitsted ob.
tanning this information by wireless from
vessels at sea and by telegraph from the
extreme coast stations. 1t was said that
Agassiz could draw the outline Of q fish
from the study of single scale, so too the
skilled meteorologist could draw with a
certain amount Of success a weather map
Tor Western Europe for the next dav if he
had but single reading Of barometer
made on shpboard four or five hundred
miles off the coast. In lieu of the barometer
reading to the westward the movement Of
the locally observed high lying clouds was
the best substitute.
The daily weather maps for Western
Europe, supplemented by hourly reports Nv
wire wireless telegraph, formed n neces-
sary adjunct for all military and naval air
flying. Such weather maps have been made
both in England and France for many years
These weather maps, supplemented by the
knowledge Of local weather conditions, were
most carefully studied by the aviators and
formed the basis for flying plans. Germany
had its own weather maps as we'll as The
Allies, but the Allies had an advantage. for
they could follow the weather conditions
into Germany far better than the Germans
could foretell the weather on the British
or French coasts kilograms from Scan
dinava or wireless messages from their sub
marines were the only methods except from
observations of the upper clouds by which
the Germans could forctell approaching
weather.