CONVECTIVE STORMS AND SCAVENGING
931
volved the following: determinations in rain samples of total dissolved
and total suspended beta activity and of ®°Sr and *°Sr; a feasibility study
on hailstones from the May 26, 1963, Midwest City storm; development
of beta scintillation spectroscopy techniques; and evaluation of the ef-
fect of dust on the rain collectors on the radioactivity levels found in
the rain samples. Modifications were made for the 1964 season. Measurements of the radioactivity of dust were discontinued, and there
were no hail collections. The decreased level of atmospheric ®Sr ac-
tivity led us to discontinue that analysis in view of the greatly increased
number of rain samples obtained by the sequential collectors. Em-
phasis in the 1964 analyses was in determining the beta activity in the
rain samples. Strontium-90 analyses were made on most of the rain
samples but not all because of the time and the cost involved. Gammaactivity determinations were made as time allowed in the course of the
other analyses.
Preliminary results of the 1964 operational season are presented
in the paper by Hall.* Analyses are still in process; therefore conclusions drawn from the 1964 data are merely tentative.
*See paper by Samuel J. Hall, this volume.