WMOD00313

• Title: Cloud Physics Studies in Utah During 1978
• Date: 9/1/1978
• State: UT
• Weather Modification - Doc Type: Report

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concentration measured by the probe was 15 2-1, but approximately 17%
of the time concentrations > 10 2-1 were encountered. The average 2D-P
concentration measured by the probe was 2.5 2-1, but 15% of the time
2D-P concentrations were> 5 2-1.
Figure 4.1. 19b summarizes the results along the 3 km leg (-70C to
-90C). From 1650 to 1750 the average FSSP liquid water content was only
O. 1 g m-3. The average JW value was < 0.1 9 m-3. The average concen-
trations measured by the 2D-C probe increased from 5.6 2-1 at 4.5 km, but
along 22% of the leg, 2D-C concentrations exceeded 10 2-1. Concentra-
tions measured by the 2D-P probe showed an average value of 0.9 2-1 (in
comparison to 2.5 ~-1 at 4.5 km), and there were essentially no concen-
trations > 5 ~-1.
The measurements of liquid water indicated a slight decrease in
average value from the upper to the lower legs, but large liquid water
contents were encountered more often on the lower leg. Ice particle
concentrations measured by the 2D-probes decreased by a factor of three
from the upper to lower leg.
Figure 4.1.20 is a flight track on which observations of ice nuclei
are indicated. It may be noted that during the penetration at ~ 1648
discussed in Figure 4.1.14, concentrations greater than 5 ~-1 were ob-
served 30 to 40 percent of each individual minute. Concentrations of
ice nuclei were observed within a number of convective elements during
the northbound leg. One significant plume of ice nuclei was encountered
between 1725 and 1730. A smaller plume was observed between 1715 and
1720, and one small indication of nuclei was encountered at 1707 during
the southbound leg. During the climb out from Provo between 1753 and
1755, some small concentrations of ice nuclei were observed at the +1 to
-2QC level.

SUfr~Y - Flight #2~ 12 March
There was convective instability present behind the frontal system
and it was being released over the Wasatch Range. Significant concen-
trations of supercooled water and low concentrations of ice particles
and ice nuclei were observed during the southbound leg. During the higher
and hence colder northbound leg, and during a number of penetrations of

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39 .