will fall first,
near the explosion.
Lighter ones will he carried on winds,
hundreds or perhaps thousands of miles,
hefore settling to the qround
naturally from the force of qravitv, or more rapidly should they become mixed
in a weather front and be brought down in a rainfall.
qenerally referred to as "local fallout."
and lands within a few hours,
that is,
or days.
isotopes of many kinds,
i,e.,
This is what is
It is heavily radioactive in nature
[It contains "mixed fission products"”-strontium,
cesium,
iodine,
giving off heta and aamma radiations of different energies.
zinc,
cobalt,
Generally this
local fallout can be seen in a cigar-shaped pattern, with the lightest
activity at the outer edges and the heaviest toward the center.
Not all of the fallout,
days.
however,
comes down in the first few hours or
This is the material which has heen injected into the stratosphere
{a zone beainning at ahout 40,000 feet).
The particles which have ascended
to this heiqht and above in the towering cloud are very fine and lidqht, like
particles of smoke.
These radioactive particles will he circulated about
in the stratosphere--which rarely has clouds and in which the temperature
is relatively constant--until it has spread out all over the earth.
This
Material will take months and years before it has returned to the earth's
Surface,
The radioactivity, which may be spread throughout the world more
or less uniformly,
will return to the earth in the sane manner,
although it
is possible that some areas of the world will receive heavier amounts of this
fallout than others.
How this radioactivity, once it has returned to the earth, comes to he
‘consumed and retained hy man is due to one of the unicue properties of
radioactive materials.
Mg 0282
18