Heteorological Factors Affecting Spread of Radiosctivity fron Nuclear Boxbs
By
lester Hachta
U. S& Weather Bureau
Washington 25,
D.C.
Novenber 15, 1956
A talk delivered at the Washington Academy of Sciences
Introduction
Ths fissioning of a nuclear weapon is the first step in a chain
of events which my ultimately result in the ill-effects of radioe
activity on man,
The dispersal from test site to hu-an environment
or food takes place largely through atmospheric transport.
The ©
problem, however, is more than the application of the usual winds to
carry the particulate debris.
It will bs apparent that eddy diffusion
amd precipitation, for example, also play an inportant role.
Nost persons who have treated the entire radioactive fallout
spectrum have found it convenient to divide the history of the partie
culate fallout into three categories.
First, that which deposits
out in the first dsy, or less. This is designsted as local fallout
since in this short time the horizontal displacement cannot have
been very great.
The second class 4s deposited betwasn about 1 day
and a few months. For lack of a better word, it will ba termed
internediate fallout, Finally, ths fallout celivered beyond a few
months is called delayed fallout.
Because the particles are injected
4n the stratosphere and found ovar much of the globe, it is also
referred to as "world-wide stratospheric fallout*.
It is ths purpose of this discussion to point out the mstsorologl=
calconsiderations which account for ail-ofthe atmospheric transport
offa"Edris. Remarks on local end internediate ranges will be brief,
thile those pertaining to delayed fallout, more extonsive. |