340
KNOX
neously mixed only in the lower fifth of the cloud. A similar prescription of activity—particle size is used for the base surge. Figure 4
summarizes the parameters governing the activity—particle size dis-
tributions in the two clouds at the time of cloud stabilization. These
parameters governing the activity—particle size distributions in the
G
r
[
=—— 0.8(1) Fe
!
wm (1)
In Tm (1) 4
om (1)
~
wb (2)
In 7 (2)
a, (2)
'
wm (2)
In te,
(2)
i
a, (2)
4
Quy (2.
0.8 wy, (2)F,
2m
we (1)
i te 02m (1) Fe beth
HC)
SURFACE
ZERO
A
Fig. 4—Schematic drawing of an idealized cloud from a subsurface
detonation showing spatial relations of the activity—particle size distribution assumed in the model.
cratering fallout model have been determined by mathematical experimentation with the model in the re-creation of the observed fallout
patterns for the Sedan and the Danny Boy shots. Results of these calibration calculations will be discussed in a later section.
Terminal Fall Velocity of Fallout Particles
The vertical fall velocities of the fallout particles are modeled as
the terminal fall velocities of smooth spheres of density 2.5 g/cm? in
an International Civil Aeronautical Organization standard atmosphere
as computed by McDonald’ for both the Stokes’-law region and the
aerodynamic region (wherein the Reynolds number exceeds 1). If some
fallout particles are a cluster of small spheres attached to a large
central particle, these complex particles are assumedto fall with the
speed of the equivalent smooth spherical particle of the same mass.
Experimental evidence has been obtained by Rapp and Sartor’ to support this assumption.