APPLIED METEOROLOGY FOR THE AVIATOR
_Activities of the Weather Bureau in Relation to
Aëronautics._--Naturally the progress of aërial navigation has at all
times been rather closely connected with the Weather Bureau. For over
a decade the Bureau has not been content with surface observations
but has maintained laboratories for the study of the upper air. The
results of its observations are considered a mine of information for
the student aviator. Prof. Charles F. Marvin, the Chief of the Weather
Bureau, is a member of the National Advisory Committee for Aëronautics,
and chairman of a subcommittee engaged on the determination of the
problems of the atmosphere in relation to aëronautics.[E]
[E] Monthly Weather Review, 1915, 32:500. Washington.
The first official coöperation between the Weather Bureau and the War
Department aviation school was inaugurated in the year 1914 by Dr.
W. J. Humphreys, Professor of Meteorological Physics, when he was
detailed to give a course of lectures. It was during this course that
he lectured on “Holes in the Air.”[F] This paper has been reprinted as
a textbook for the aviation school.
[F] Popular Science Monthly, 1914, 44:18–34, N. Y.
_Early Studies in Aëronautics._--Unofficially, however, the coöperation
extended back some fifteen years prior to that time, when the writer
was in charge of the local office of the Weather Bureau at San Diego,
and assisted the aëronautical engineer, Octave Chanute, in his
observations and experiments on San Diego Bay.[G] At this time hundreds
of photographs of sea-gulls, pelicans, and other soaring birds were
made, and both birds and photographs studied and analyzed. Ever since
then more or less interest has been taken by the writer in aërial
navigation. During an assignment to the Central Office the work of
the Wright brothers was observed and studied. The association with
the late Octave Chanute and his friends, the Wrights, during their
experimental flights at Fort Meyer, Virginia, in September, 1908, is
counted among the many pleasant memories of the Washington visit. It
was here that was witnessed the first flight with a passenger (see Fig.
4), Mr. Orville Wright taking up with him Major (now Colonel) George O.
Squier, the present head of the aviation branch of the army. Such was
the infancy of the flying-machine that at that date no fatalities had
occurred. A few years later the writer had the pleasure of accompanying
Mr. Glenn Curtiss while he was determining a site for his school, which
was finally located on North Island. (See Fig. 6.) Shortly afterward,
from this place, Harry Harkness made record amateur cross-country
flights in an Antoinette monoplane.
[G] “Climate and Weather of San Diego,” Carpenter, 1913, 57–59,
San Diego.
_Active Work of the Weather Bureau._--During the score of years that
the writer has been in charge of the San Diego and Los Angeles stations
of the Weather Bureau, interest in flying has been cumulative. Efforts
have been made to furnish aviators with available data so that at the
present time a day seldom passes without conference With officials or
students of Government or private flying schools in this vicinity.
_Lectures on Meteorology as Applied to Aviation._--Through the War
Department, October, 1915, on request of the commanding officer of the
Signal Corps aviation school, at San Diego, the writer was directed by
the Chief of the Weather Bureau to deliver two lectures of which the
following are outlines:
“_What the Weather Bureau Offers the Aviator_”
(Illustrated by 37 lantern-slides from photographs by the author)
Introductory:
Weather service once part of the Signal Corps, U.S.A.
Transfer in 1891 to the Department of Agriculture.
Distribution of weather stations in the United States:
Character of data obtainable:
Advance data from the daily map such as
Position of high and low areas.
Weather conditions from sub-stations in vicinity.
The weather map:
How constructed.
How distributed.
Specimen maps showing differing conditions in California.
Winds, velocity and frequency:
On-shore.
Off-shore.
Discussion of air conditions December 20–22, 1914.
The international weather map.
Relation to weekly forecasts.
Cardinal climatic features:
Ascending winds and types producing them:
Cloud, fog, precipitation.
Descending winds:
“Northers” and dust-storms.
Thermograph and hygrograph traces.
Factors in the meteorology of southern California:
Influence of latitude:
Sea.
Mountains.
Desert.
Path and distribution of storm areas.
Knowledge of local climatology necessary in flying.
Local winds discussed:
“Woollies” (descending wind eddies).
“Chubascos” (south coast thunder squall).
“Santa Anas” (northeasterly and desiccating).
“Wilmingtons” (northwesterly line-squall).
“_Practical Meteorology for the Aviator_”
(Illustrated by 72 lantern-slides from photographs by the author)
Historical:
Original work begun in Scotland, year 1749.
Characteristics--
English work; Dines’ minute meteorograph.
French work; Dr. Berson’s balloon ascent of 6½ miles.
German work; detailed data in low altitudes.
American work began with Franklin.
The Upper Air:
Definition:
“Stratosphere” is (according to some authorities) the
dynamical laboratory of the atmosphere where the
main causes of pressure originate.
Results in America:
Balloon meteorograph (Fig. 3).
Charts showing rate of increase in wind velocity with
elevation (Chart No. 4).
Wind, temperature, pressure, humidity at maximum airplane
height of 26,242 feet.
Stratosphere:
Lower level in winter than in summer.
Lower temperature in summer when surface pressure is
high.
Definition:
“Troposphere” is the physical laboratory where cloud
and rain are produced by local causes and induced
by the effect of the dynamical changes in the upper air.
Conditions within 6 or 7 miles of the earth’s surface.
Clouds and their Meaning:
Cirrus:
Height and composition.
Formation:
Perpendicular shafts of clouds indicate rapid changes
in weather.
Horizontal layers, no change and clouds will dissipate.
Cirro-stratus, threatening in winter.
Cirro-cumulus, fair and foul varieties differentiated.
Cumulus with strong uplift.
Alto-cumulus, cause of parallel rows.
Fracto-cumulus, wind indicator, Point Loma “woolly.”
Stratus.
Alto-stratus, favorable for flying.
Strato-cumulus, long shallow rolls, threatening in winter.
Cumulo-nimbus, unsafe air conditions for flying.
Fracto-nimbus, waterspouts and their causes.
Velo cloud, examples, cause, effect, distribution, density.
Fog, examples of great fog-belts.