Evening star. [volume] (Washington, D.C.) 1854-1972, 1926-09-21

portions are considered more danger
GUS because the wind velocities are
somewhat larger. They never
originate on land. and if they run
ashore they weaken and are trans
formed into eXtratropical cyclones
They are never in the South Atlantic.
"They originate in the doldrums, 8
to II degrees from the Equator on
either side. On the Northern Henri
sphere they curve to the right at 80
| degrees north.
THE fundamental principle Is i'm
connection with convection, which is
the effect of the earth's rotation on
moving air"
| Convection means a perpendicular
current of air)
Convection is most vigorous i'm
| stagnant, Overheated, moisture-laden
| air. Moist air rises, expands, grows
cooler and reaches it's dew-point-be-
| comes cloudy, and precipitation fol-
| lows. Latent heat is liberated by the
| condensation of water vapor into
| rain, and this will lessen the rate of
| cooling in the rising air and cause
81 greater rise.
Cooler air forcing its way in. to re-
place the rising air. would he defect
ed to the right in the Northern Hem
| isphere by the earthS rotation and
approach the center in a counter
clockwise turning spiral.
This rotation of air around the
center would cause centrifugal force.
which would hold the air away from
the center, thus causing a still lower
barOmetric pressure. This increase
in the difference between the center
and surrounding region would cause
a further rise of air in the center.
This would cause more clouds, more
precipitation, more latent heat and
still more vigorous rise.
This in turn would cause still more
air to come toward the center, which
would make the whirl more vigorous.
causing more centrifugal force, and
still lower barometric pressure In the
center. This, again, would drive the
whole circle with still more vigor,
and in this way the violence becomes
greater and greater until the tropical
cyclone is the result. The air rising
in the center would continue to rise
until cooled, due to the expansion. to
the temperature of it's surroundings,
when It would spread out laterally,
still carrying a slight excess of mois-
ture with it. 1t would then settle
down in surrounding regions, caus-
| ing a slightly higher barometer"
Within only the last two or three
years have mariners attempted TO
profit by the warnings of the weather
/; forecast. 1t is related that q small
freighter called the Kittery, on the
| Hampton Roads-West Indies run, in
1924 paid special attention to plot
ting the radio weather signals sent
| out twice daily from Arlington. Va.
| The signals were recorded on a blank
weather map on board ship. and by
means of them the skipper noted the
| paths OF approaching low barometers,
, and so 'evaded q great hurricane In
, August, 1924. A month later, the same
/ means warned the Kittery OF the ap-
| preach of storm, and the skipper
| found a clear-Weather passage down
the coast west of the Bahamas. He
! took that route and enjoyed fair
weather all the way, while a storm
ragged so severely east of him that It
| took 81 lives on the Island Of Tor
| tola.
| Within the last fortnight demon
| stration of map broadcasting by radio
has been made at Arlington and the
| Weather Bureau. This will enable
every ship at sea to receive by radio
| broadcast detailed weather map
daily, which will show just where the
| danger routes are nav hours ahead.
and enable ships to run out Of the
| danger zone.
| The first signal by the Weather
| Bureau of the coming OF this recent
| storm was sent on last Tuesday. The
storm center then was off the Virgin
Islands. Later it was noted not far
from the Bahamas, travelling toward
Florida at the rate of IL miles an
hour, with a velocity of wind exceed
ing 100 miles, and warnings were en-
phasized by the Weather Bureau. It
arrived in all fury Saturday night.
Thus shipping could have had four
days to get out Of danger. Land
points also were warned. but nothing
can be done with buildings IL they
are In the line of destruction.
lCoDyright. 1896. by Paul v. CouanA1