Evening star., 1950-08-21
Scaling Laws Provide
Measure of A-Bomb

measure OF A-DOmD
Many Serious Misconceptions
Removed by New Formulas
By Thomos R. Henry
The magnitude of an atomic explosion
is not direct measure Of the extent of
damage it will cause by shock waves,
heat or radioactivity.
However, the area of devastation can
be calculated by series Of So-called
scaling laws" - mathematically some
what complicated, but calculated to re-
move some serious misconceptions.
Simplest are those dealing with the
shock waves, the moving walls Of air
from the great ball Of fire which imme-
diately follow blast and which are
responsible for the greatest part Of the
devastation.
Assume that an atomic explosion
equivalent to 10000 tons of TINT sets up
shock waves which will knock down
solidly constructed buildings at a dis
tance Of $500 feet. This does not mean
that blast equivalent to that of 80, 1000
tons Of INT will cause the same degree
of damage over radius so per cent
greater, or about 4,25o feet. Actually.
the just published scaling laws show. the
damage zone will be extended only 23o
feet. 80
The proposed hydrogen bomb has been
estimated potentially to be 1000 times
more potent than the present uranium
bomb. Naturally, this does not mean
that its damage would extend over an
area 1,00o-fold greater. II the total de-
struction radius Of the present bomb is
half mile, that of the proposed bomb.
according to the present theory would
be somewhat less than so miles.
Laws Are Major Revelations.
These scaling laws are one Of the
major revelations in the far-reaching
report on the effects of atomic weapons
issued by the Atomic Energy Commis-
sion Admittedly they are somewhat
theoretical, since it is impossible to test
them by actual experiment.
Quite different scaling laws must be
applied to the great heat waves which
accompany the shock waves, setting fire
to everything infiammable In their path
For a conventional atomic bomb heat
and shock will move together and devas-
tate about the same area in the same
time. The heat tends to dissipate into
the surrounding atmosphere much more
quickly, however, so that for very large
bomb of the proposed hydrogen type the
extent Of fire damage would not be very
much greater than that due to the con-
ventional bomb.
Separate scaling laws, which involve
considerable mathematical complica-
tions, must be applied for each Of the
types Of radioactivity accompanying a
bomb explosion - beta, alpha, gamma
and neutron. For the first two types the
range of damaging activity would not be
very much greater regardless Of the
magnitude Of the explosion.
Can't Alter Weather.
Atomic bombs cannot materially alter
weather.
The enormous energies released are.
after all, puny, compared with those
necessary to create or stop rain and
thunder.
This is the conclusion of Atomic Energy
Commission experts. -. -.
There has been considerable specula-
,tion over the possibilities, especially If a
bomb were exploded over water. First, it
was thought that large amounts Of rnois-
ture in the air, such as is common in
tropical areas, together with the moisture
evaporated from the surface of the water
might result in thunderstorm forma-
ton. Second. there was possibility that
the great number Of particles shot into
low clouds would serve as nuclei for the
condensation of rain drops.
But nothing of the sort has been OBJ
served in atomic explosions to date.
Thunderstorms require the transport
aloft of great masses of moist air over
wide areas and considerable periods. The
effects OF an atomic explosion are almost
instantaneous. They are unable to pro-
duce the sustained reactions necessary
for thunderstorm formation. Even if the
atmosphere is on the verge Of thunder
storm conditions anyway. it is pointed
out. the sudden impulse Of an atomic
explosion cannot precipitate thunder
storm because the energy release is so
rapid that the atmosphere is unable to
rearrange itself, within the limited time.
so as to take advantage Of the addition
energy.
The number of particles shot into the
upper atmosphere, it is stressed, would
not be sufficient to make much difference.
The suggestion has been made that
hurricanes, tornadoes or cold waves
might be dispelled by the sudden release
Of the large amounts of energy from an
atomic bomb. Actually, the experts re-
port. the amounts of energy necessary
for any such result are far beyond any,
thing at present attainable.
There was intermittent rain over the
explosion at Hiroshima but this was due
to the widespread fires which sustained
moist air long after the blast itself.
Similar showers were caused by burning
cities and forests In Europe during the
last war.
"A careful examination Of all the
available evidence" says the report.
would lead to the conclusion that an
atomic bomb burst has a negligible effect
on weather"
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