Evening star., 1921-04-07
EXPLAINS FRANKS
PLAYEDBY Winds
Geographic Bulletin Says Air.
planes Will Never Go 500
Miles Per Hour.

tlon plays queer pranks with the at
mosphere." says a bulletin issued by
the National Geographic Society, "but
scientists find the various swirls fol-
lowing fairly definite laws. The
worlds winds and their complexity
are due in general to two forces: The
rapid rotation of the earth, which is
impaired to the air surrounding it.
/ and notifications of this motion, due
! earth's surface.
! II the temperature differences did
not play part in the matter, it is
probable that there would be only
west winds in the embperate and
| polar zones, and no winds at all in
! the tropics. The situation would be
somewhat like that brought about
( in glass of liquid at a soda foun-
| tam IN which rotary stirrer is
introduced. The liquid swirls faster
and faster until finally it attains prac-
! tically the speed of the rotating rod.
/ So, but for temperature differences,
| the earth would have the great sea
! OF air which surrounds it swirling
with 1t practically at the speed with
which the earth moves. at the. equa-
| tor-approXimately thousand miles
an hour. But, since both the earth
/ and the air at the equator would be
moving al the same speed, there
would be no wind there.
Air Would Outrun Earth.
AS one went from the equator he
would find wind blowing harder
and harder as he approached the
poles. This wind would be from west
! to east. the direction in which the
| earth is turning: and would result
from the fact that the air was turn
ing through space actually faster
than the earth. For while the sur
face of the earth at the equator is
moving at about a thousand miles an
| hour, being on the rim of the wheel
so to speak. the surface in the tenn
perate zones. being nearer to the
huo, is moving at slower speed.
| But the air above the equator, swirl
ing at thousand miles an hour,
| would communicate it's speed to the
| air on each side of it and would tend
| to throw the entire atmosphere to
spinning at the rapid equatorial rate.
AS result. it would outrun the earth
| between the equator and poles and
create mighty west wind.
AS matter of fact much of this
assumption is true. The earth does
lmpart its rotary motion to the at
mosphere in general, but because of
| counter influences and side currents
\ que TO temperature differences. the
assumed calm is not found in the
| tropics Instead, the earth outruns
the air somewhat there. and the air.
dragging as the earth spins under
4
| east-the famous trade winds. But
| even though the atmosphere is amov-
| ing eastward more slowly than the
earth at the equator. it is moving
faster than the earth in the TEMPER
ate zones. and there the prevailing
\ winds are from the west
| Air Stream Seven Miles Up.
| Temperature differences, of course,
change the general directions of these
| planetary winds. especially at the
surface of the earth. But in the
| United States at an elevation of six
may be found blowing from the west
| at from sixty to seventy-fve miles an
| hour.
| There seems to have been much
oVeroptimism in regard to speeds
| that can be attained by aircraft with
the help of these planetary winds. IL
mas been stated On some instances that
| IN upper currents moving at 300 miles
an hour aeroplanes with powerful
motors could reach speeds Of 400 or
that no winds have been found in the
upper air by the United States wealth
er bureau in many years of observa-
tion that much exceed 100 miles an
hour' and the normal speed of the
west winds at high attitudes over the
United States is between sixty and
seVenty-five miles an hour, If such
| tremendous speed as that suRgested
| - 10 pc attained by aeroplanes, there
| fore. the motors will have to be re-
sponsible for the greater part of il.
The winds of highest velocity have
been found about six or seven miles
above the sea at the level Of the high
est clouds. Both above and below this
| level the speeds fall off.
Balloons Furnish Evidence
The rates Of motion have been check
ed by observing the drift F special r,1h
Der balloons. The observations are
made through telescope instruments
| from the ground. Similarly the drift of
clouds has been observed and measured
thousands of such observations have
! peen made. ranging from slight dis
tances above sea level to the upper
! reaches of the clouds. and, in the cases
OF balloons. far beyond the cloud zone
one balloon sent up by the weather bu-
reau reached height of nearly twenty
miles.
! THE winds of the upper attitudes in
addition to keeping the atmosphere stir-
red up. affect weather in another way
under exceptional conditions. When vol
canoes throw dust and ashes into the
upper air-sOmetimes fifteen or twenty
miles up-the planetary winds quickly
spread the particles, forming an enyei-
ope entirely inclosing the globe. This
sheath screens Off many of the short
heat waves coming from the sun, but
does not interfere materially with the
passage outward of the longer heat
waves radiated by the earth. The earth.
therefore, loses heat in two ways, and
as result the average temperature all
over the world is lowered for some time
after the more violent volcanic erup-
fiopSv