RADIOACTIVITY IN PRECIPITATION
551
of station 8, which had an initial strong rainfall rate of 1.32 in./hr, the
initial rainfall rates were moderate, generally less than 0.5 in./hr.
At all the stations the rainfall rates increased after the initial burst.
At stations 5, 6, and 10, the initial samples had the maximum beta
concentration, whereas at station 8 the concentration decreased from
an initial secondary maximum then increased to a maximum. The
beta~concentration profiles at stations 7 and 9 were similar in that the
beta activity at these stations increased to a maximum in the second
samples taken at these stations and then decreased to a minimum.
Aside from the general inverse relation between rainfall rate and beta
concentration, three of the six stations (stations 6, 8, and 9) showed
such an inverse relation at the time of later maximums or minimums
in beta concentration, but two of the three cases (stations 8 and 9) are
not well defined,
The ratios of particulate to dissolved beta activity were maximums
in the initial samples at stations 6 and 10. These values were 1.23 and
1,33, respectively, The ratios at the other stations were quite low,
around
0.5.
Table
1
shows
that, with few notable exceptions, the
particulate beta concentration is considerably low at most stations,
with the average of all samples for this storm being 82.3 pc/liter and
the ratio of particulate to dissolved beta activity being 0.85.
The major cells that crossed the network are shown in time
Sequence in Fig. 27. The area of maximum intensity, 48 db, passed
between three to eight miles south of station 8 and at this time had
radar tops at about 52,000 ft. This shows stratospheric penetration of
more than 10,000 ft since the tropopause height was around 41,000 ft
(see Table 2). The time cross sections of radar tops show that there
was no tropopause penetration over the collectors.
By a relation of the data of Fig. 27 to the rainfall collections, it
is seen that at station 6 the beta concentration was at a minimum as
the echo-intensity maximum crossed the station. This was the only
station that
appeared
to be
crossed by an intensity center in the
storm, and the corresponding beta concentration was the minimum for
that station and for that cell. This area of the storm was dissipating
as it progressed eastward over station 7, and the rainfall-rate maximum had decreased but was still of a relatively strong intensity.
Instead of a minimum in the beta concentration, there was a maximum
associated with the rainfall-rate maximum.
The cell structure that crossed station 8 was rather complex.
Figure 27 shows that as the intense echoes were approaching from the
west development was occurring east of and over the station. Figure 18
shows
that the beta concentration was not at a minimum when the
rainfall rate was at a maximum, but that the minimum concentration
occurred when the maximum echo intensity was inits closest proximity
Or
to station 8 and the rainfall rate was still strong. The absolute maxi-