Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-08-10

all hearts Then, suddenly, from
nowhere it seems, light breeze springs up.
Directly the breeze heightens into a wind
which rises higher and higher. Birds flee
screaming Rain begins to descend in tor
rents In this moment the hurricane breaks
with indescrbable fury.
But what touches off a tropical hurricane?
Scientists are familiar with the conditions OF
the atmosphere which form the setting OF
hurricane. but they have never been able to
put their finger on the precise thing that sets
It OF.
..The weight of evidence is overwhelming"
declares Dr. Herbert Janvrin Browne, oceano-
graphic meteorologist OF washington, u u
that during hurricane seasons marked drops
in solar radiation precede at short intervals
and bring on West Indian and other hurricanes
of the tropical and subtropical oceans in zones
of Gains low rainfall and high surface temper
atures.
This means that it is now possible to fore
cast tropical hurricanes several days In adj
vance of their origin-something never before
nossible-and in the near future scientists may
determine the places of their origin, paths,
force and direction"
Dr. Browne arrived at his conclusions-Whch
he calls THE Law of Tropical Hurricanes =
quite recently, after several years OF study OF
hurricanes in all parts Of the world, together
with the Immediately preceding and follow
ing six or eight days of solar constant figures
He used hurricane records covering period
of 81 years, supplied by the United States
Weather Bureau; pilot-chart data, supplied by
the photographic ONCE, United States Navy,
and standardization data, supplied hy the
astrophysical laboratory Of the Smithsonian
Institution, of which DR.. Charles c. Abbot is
head.
drop in solar radiation Is the thing that
~u,IlIs the trigger" of o hurricane, Dr. Browne
contends And to show how it does it, let us
build I'D a hurricane, hguratively, and touch
it off,
TT~HE first thing required is high tempera-
Il ture at the surface of the ocean-in order
tn uroduce the required moisture in the lower
air Second there must be cold air above,
either from q nearby cold-water area or some
other cold-air source. Our hurricane is now
ready to go. It remains only to be set on
This is accomplished by supplying sharp
drop i'm solar radiation. This drop causes
cessation of virtually all winds Of a horizontal
character up to the levels of condensation.
The cessation of these winds permits the
humid air rising from the sea to enter booly
into the cold-air area aloft for swift condensa-
ton, with the release Of great latent heat,
resultant from . sharp drop in pressure. Thus
is the hurricane touched on" 1t now moves
swiftly and spirally across the ocean, gaining
momentum and widening rapidly as the humid
air continues to ascend spirally to the low
pressure aloft, equivalent TO a partial vacuum
Conditions of the atmosphere WHICH bring
on high rainfall, with sustained wind activity
before and afterward, will, says DIR. Browne.
result in dynamic atmospheric readjustments
without necessarily producing hurricane"
AS proof Of this he cites the Bay of Bengal
during the Indian southwest monsoon, when
rainfall is notable. In other oceanic areas on
or In close proximity to the Equator, true hurri-
canes do not take place he states. The reason
lies i'm the fact that the earth's curvature near
the Equator is too slight to produce rotation
and accelerate the spiral formation necessary
to it's full development and progress.
There are four great hurricane areas in the
world. More hurricanes occur in the Pacific,
east of the Philippines than anywhere else.
Second-ln numbers-is the North Atlantic,
west from the Cape Verde Islands to the West
ern Caribbean The Bay Of Bengal ranks
third. Fourth place goes to the oceanic waters
around Australia-the South Indian Ocean
especially the southeastern part Of that ocean.
Other important hurricane spots are in the
Southern Pacific and off the coast of Mexico.
The South Pacific area may also be a great
hurricane belt scientists declare, but it is too
little traversed TO be classified definitely.
In the North Atlantic the point of origin
of hurricane must be over warm water near
cold water This condition is found near the
Cape Verde Islands and the southern limits Of
the Az0rean coId-water area. In both these
areas cold air exists aioft for the condenSa-