Perth Amboy evening news., 1921-10-21
WHY THE WINDS BLOW

T the layman, the worlds rota-
ticn plays queer pranks with the at
mosphere,' says a bulletin issued
from the Washington, ID. c., head
quarters of the National Geographic
Society, "but scientists find the va
rious swirls following fairly def
mite laws. The worlds winds and
their completely are due in gen.
eral to two forces; the rapid rota-
ton of the earth which is impaired
to the air surrounding it, and modi-
fications of this motion due to diff
ferences in temperature on the
earth's surface.
IF the temperature differences
did not play a part in the matter,
it is probable that there would be
only west winds in the. temperate
and polar zones, and no winds at
all in the tropics. The situation
would be somewhat like that
brought about in a glass of liquid
at a soda fountain into which a
rotary stirrer is introduced. The
liquid swirls faster and faster UNI
til finally it attains practically 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
it practically at the speed with
which the earth moves at the equa-
tor-approXimately a thousand
miles an hour. But since both the
earth and the air at the equator
would be moving at the same speed
there would be no wind there.
Air Would Outrun Earth
"As one went from the equator he
would find a wind blowing harder
.-I L.,lA ne, he .~npAnaho1 tho
poles. This wind would be from
west to east the direction in which
the earth is turning, and would re-
suit from the fact that the air ".
turning through space actually fas-
ter than the earth. For while the
surface of the earth at equator is
moving at about a thousand miles
an hour, being on the rim of the
wheel SO to speak, the surface
in theN temperate zones, being
nearer to the hub is moving at a
slower speed. But the air above
the equator, swirling at a thousand
miles an hour would communicate
its 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 a re-
suit it would outrun the earth be-
tween the equator and the poles
and create a mighty west wind.
LAS a matter of fact much of this
assumption is true. The earth does
impart it's rotary motion to the at
mosphere in general, but because
Of counter influences and side cur-
rents due to temperature differen-
ces, 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 it, makes winds
blowing from the east-the famous
trade winds. But even though the
atmosphere is moving eastward
more more slowly than the earth
at the equator. it is moving faster
than the earth in the temperate
zones. and there the prevailing
winds are from the west.
Great Air Stream Seven Miles CI
Temperature differences, OF
course change the general direc'
lions of these planetary winds. es-
pecially at the surface of the earth
But in the United States at an ele-
vation of six or Seven miles a near
ly constant wind may be found
blowing from the west at from sc
to rs miles an hour.
There seems to have been muck
over-optimism in regard to speeds
that can be attained by aircraft
with the help of these planetary
winds. 1t has been stated in some
Instances that in upper current:
moving at three hundred miles al
hour, aeroplanes with powerful mo
tors could reach speeds of four OF
Eve hundred miles an hour. Th'
difficulty is that no winds hav,
been found in the upper air by tn
United States Weather Bureau il
many years of observation tina
much exceed 100 miles an hour
and the normal speed of the Yves
winds at high attitudes over tn
United States is between 60 ant
rs miles an hour. If such tremen
dous speed as hat suggested is Il
be attained by a~eroplanes. there
fore the motors will have to b.
responsible for the greater par
of il.
'.The winds of highest v~elocit!
have been found about six or sever