WECLASSVELEY
i
2.
The basic
a,
assumotiors °:f
The whole c.cud
the met’ x
ur‘tc its he. gt’
at the time of cetomatior.
In any heigtt
ace
This
.ave> 7 the
.&
*y) lows:
oy
he
:* «tantlization, is formed instantaneously
4 e+ at
initia
we cali the "initial cloud",
-.:us,
the concentration (radioactivity
per unit volume, is distributed ax o-t:.g to the Gaussian law
Gh, ry &e
7
ty) hl
exp
oe
where cih) is the - an ural concemra.,o at heigtt h, r is the radial
horizontal dista'ca, and a
is a “s reac parameter” (analogous to
standard deviation: t at is a.sc 023 dered to be a function of height.
From this assumptior
in a slice c* un"
Throughout @ .
normally wit’
particles,
>
t+ follows '"s°
0 # total amount of radioactivity
vertical thick:esany suc’.
8
layer, ‘re castoactivity is distributec
respect 2c the Logarditr;:
“his
at
falls with speed:
1
ary distance .
ic tne vange 7.
exp
O (hoo 2
tre
° the rate of fall cf the
*raction of radioactivity that
° «+ df is given by
to
els
oo. 40
|
a
Teolh, a@oé.
|
_fth,
nh
STR
ae
-
where f(hi is tne fari-rate fo: pari. .es of greatest radioactivity,
and. (also consiietec to be a funct:o.
% neight} is the standard
deviation of «ne .ogarithm cf fai.-ra*es, weighted according to radioactivity.
f(h) and © (Fi @re vonstact thrucut c+ ayer.
The rate of fal.
° an’ partic 4 -emA: 13 :o1stant until it reaches the
ground,
Any particle hat starts from t-e ertca. axis wiil follow a path strictly
tre wind patver', «
4r accordance wit:
at the same rate ‘rom the same
central parti .e
°
.¢ all otner particles that fald
eve. wo: diffuse laterally fram the
sur? # way ‘ha’
t’*
gaussian distribution is maintained.
ee! ACCITIFD
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