Evening star., 1933-04-06
AKRON DESTROYED
|. BY VERTICAL Wind
Phenomenon Causes Thun-
der Lightning and Hail
Says Geographic Society.

Down drafts that sucked the Akron
to its doom of Barnegat Light again
direct attention forcibly to the fact that
winds blow up and down as we'll as hori-
zontally. It was a vertical wind" that
destroyed the dirigible Shenandoah
over Ohio in 1925.
Far from being unusual, such "verti-
cal winds lie at the heart of some of
our best known weather phenomena"
according to a bulletin from the Ma
t&pnal Geographic Society.
EVERY flash of lightning that you
see. or that you hear as thunder, anu
due to a vertical wind,'" says the
bulletin. ''These are the results of
violent upward and downward blasts.
If you consider as well the gentler ris-
ing and falling currents-the vertical
breezes' they might be called-you must
take in practically the whole field OF
weather.
Nearly every surface wind, what
ever its direction or speed, Is moving
along to replace air that has risen.
Clouds are built by rising air. On
weather maps the swirling circles that
denote lows and highs are in the
final analysis the representations of
upward and downward currents.
Production Of High"
"Where cold air from the upper
regions flows down it congresses the
surface atmosphere and produces a
high: where the air, because of heat,
Is rising, it relieves the pressure and
forms a low Most weather changes
are due to the interplay of forces be-
tween highs and lows which bring
in their train changes In wind, temper
ature and humidity.
Most spectacular Of all vertical
winds Is the thunder storm. As the
tracer bullet marks the flight of pro-
jectileS for q marksman, so the tower
ing black thunder head marks the up
ward rush of the invisible wind. Often
the violent, upsurging growth Of these
boiling clouds can be observed before
ones eye.
Thunder clouds are generally local
affairs and the wind that has rushed
upward must come quickly earthward
again to restore the atmospheric bal
ance. In the rear of thunder storms,
therefore, strong downward currents are
usually encountered. It was such an
upward then downward rush Of air that
played an important part in the de-
struction of the Shenandoah, and
which likely figured in the Akron disas-
ter.
Origin Of Great Charges.
until recent years the origin of
the great charges of electricity in
thunder clouds baffled science. Now it
is generally believed that they are
caused by the upward gusts of air
that these are in truth the dynamos of
the sky.
"The building up Of the electrical
charges Is supposed to be brought about
by the gusts blasting raindrops to
pieces, the smaller fragments carrying
negative charges upward while the
large droplets with positive charges re-
main behind. Hostile forces are set
up and when the strain becomes too
great 1t Is relieved by lightning fash
When the negatively-charged upper
cloud floats away before the strain Is
relieved, the flash Is to the earth.
Vertical winds are also credited
with the production Of hail, and their
onion-like structure bears out the
theory Raindrops carried upward by
the less violent gusts, according to this
theory, are frozen in the cold upper
air. Sinking to the seething cloud,
they take on more moisture on the lower
levels and are again carried to the
freezing region The more skyward
round trips made by the pellet before
it drops earthward, the larger the hail
stone"