RADIOACTIVITY IN PRECIPITATION
937
Fig. 7. Low-level wind flow over Oklahoma was southerly, veering to
southwesterly up to the tropopause, A single, late-afternoon storm
crossed the collection network. This storm was not associated with a
squall-line, although squall-line activity occurred about 18 hrlater
200 miles southeast of the collection network,
16
12
16
12 16 20 24
12 08 04
04
08
\_28 24 20
12
P
167
Fig. 7—-Surface synoptic chart for O0000Z on Apr. 24, 1964.
The storm approached the network from the south—southwest with
an apparent speed of 35 knots. Figure 8 shows radar-echo intensity
contours as the storm entered the network at 1709 CST. The radar top
of the 48-db intensity maximum was 56,000 ft and, as can be seen
from Table 2, had penetrated more than 15,000 ft into the stratosphere,
It is from this region of the storm that multiple samples were ob-
tained, Smaller cells continued to develop in the western portion of the
storm but were of little consequence in this complex storm.
Figures 9 and 10, the rainfall-sample cross sections and echointensity and radar storm-top cross sections, respectively, for station 8 show that the beta activity in samples varied inversely with the
storm height, the intensity, and the rainfall rate. The cell that deposited the rainfall was weakening as it crossed station 8. The radar
top had decreased to 42,000 ft, which was its height over station 8
when the rainfall was a maximum. Figure 11 illustrates the radarintensity contours at this time. The arrow indicates the axis of maxi-
mum rainfall from the cell with the head marking the northern extent
of the strong rainfall for this dissipating cell.
The ratio of particulate to dissolved beta activity increased after
the initial sample and was generally in phase with the rainfall inten-