Evening star., 1946-04-01
By W. n. Shippen, Jr.

| weather IOrecaSCerS assigned t(
the atomic bomb tests at Bikin
next July have tackled their toughest
forecast since D day in Europe.
On this occasion, however, they
must deal not only with normal
uncertainties, but with a relatively
unknown force capable Of creating
its own weather in the form OF
dangerous clouds, storms, winds and
waves.
The most critical task of Army
and Navy meteorologists is to set
a time for the explosions when the
course of atomic clouds expected
to mushroom into the stratosphere
can be predicted with reasonable
certainty.
On the day the bomb is dropped
winds should be uniform in direc-
ton at all levels from the surface
of lagoon to $4,000 to 10000 feet
Another ideal condition would be
several days of dry weather after
each of the two tests
Rain helps to precipitate radio
active particles from an atomic
bomb cloud.
Cross Winds Undesirable.
Cross winds could rip such a cloud
into sections and drive them in sew
eral directions. Under certain at
mospheric conditions the clouds
might create their own rain squalls
with resulting danger to the per-
Sonnel Of the Crossroads Operation
All of these possibilities are being
explored and guarded against by
radiation security officers and a staff
of aerologists who will interpret in
formation from hundreds of sources
ships, airplanes, free balloons and
land stations.
Although the six-week delay sets
the tests in a period of increasing
showers and thunderstorms, Vice
Admiral w. H. P. Blandy, task force
commander, expressed confidence
last week that his meteorological
staff can pick favorable days for the
explosions in time to wind up" the
whole experiment by September /
Typhoons often develop in the
Marshall islands area in summer
and fall, with resulting humidity
rain squalls and towering cloud
banks, but the storms usually gather
dangerous wind velocity only after
they move westward toward the
Philippines or the China coast.
Planes to Be Used.
The Navy's typhoon reconnais-
sance unit will be reinforced be-
fore the tests by two l2-plane squad
rons whose Liberator bombers are
being modified for weather patrol
work.
The hulls of the big planes are
being storm proofed. stripped of
armaments and fitted with extra
fuel tanks and meteorological in
struments, including radar scan-
ming sets capable of spotting heavy
rain storms through clouds or dark
ness.
Based in the Marshalls, the. Ma
rianas. the Philippines and on Oki-
nawa, the squadrons will fly weather
patrol to augment reports relayed
from three Army B-29's equipped
to make observations at very high
attitudes.
These will be sounded by air.
planes and free balloons capable of
ascending into the stratosphere. The
balloons are tracked by visual in
struments from the ground and by
radar in the upper levels to de-
termine speed, altitude and direc-
ton.
Will Enter Atomic Cloud.
Some will be equipped with radio
tranSmitters to send back tempera-
ture, pressure and humidity read
ings. Others especially designed
for the tests will penetrate the
atomic cloud to broadcast evidence
of radio activity.
From the Stratosphere to the sur
face, the movements of radioactive
dust, moisture or other matter re-
leased by the explosions will be
tracked from all angles as long as
1t remains suspended in any identi-
fable quantity. experts said. The
principal danger from the ennis
sions is at the instant of explosion,
and thereafter the energy of the
suspended particles is slowly dissi-
pated, according to observers who
surveyed bomb damage at Hiro-
shima and Nagasaki.
Experts believe the bomb clouds
will tower higher over Bikini than
they did over Nagasaki and Hiro-
shima because the stratosphere
base, or the point where the tenn
perature stops dropping as the alti-
tude mounts, is higher in southern
than northern latitudes.
Holman Heads Team.
Responsibility for translating vast
amounts of data, assembled by a
network covering tens of thousands
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