WMOD00313

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

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vertical velocities within this convective element were not different
from those outside the cloud. This indicated that this convective ele-
ment was probably mature and did not possess strong well-defined vertical
velocities. A qualitative observation was that the vertical velocity
fluctuations were greater within this element than they were on either
side of the element. 8eincreased by approximately 2 K within this con-
vective element.
The analog trace at the top of Figure 4.1.14 indicates that concen-
trations of ice nuclei were observed during the latter third of the pene-
tration and that these ice nuclei were observed to persist for a minute
or two after the penetration. This does not indicate that the ice nuclei
were only in the northern part of the convective element and extended to
the north side of the convective element, but considering the response
time of the NCAR ice nucleus counter it is obvious that ice nuclei existed
at various locations within the element at this level. The NCAR counter
shows that there were significant concentrations of ice nuclei within
this cloud on the order of 8 to 10 t-1. We were unable to determine the
exact locations within the convective element where the nuclei actually
occurred, but it is certainly clear that ice nuclei were present in the
top of this cloud at an altitude of 4.7 km.
The 2D images observed from 1735 to 1738 indicated that particle
characteristics varied significantly between the edge and the center of
the cloud. On either edge of the cloud, the particles were almost en-
tirely plate-like and stellar-like, and many particles were as large as
1 mm in diameter (see Figure 4.1.17). In the center of the cloud, there
were also plate-like and stellar-like particles. In addition, there were
some columns and capped columns (see Figure 4.1.18). Particles near the
center of the cloud were rarely I mm in size. Perhaps there was less time
for growth within the updraft regions of the cells.
The probability distributions in Figure 4.1.19 show the liquid water
contents and ice particle concentrations along the constant elevation legs
flown along the Wasatch Range.
Figure 4.1. 19a shows the results along the 4.5 km (~ -170C) leg.
The average liquid water content was 0.35 g m-3, although there were no
occasions when liquid water contents were in excess of 1 g m-3. The
maximum JW value was around 0.2 to 0.3 g m-3. The average 2D-C

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