WMOD00310

• Title: Cloud Physics Investigations - University of Wyoming - 1977-1981
• Date: 11/1/1982
• State: WY
• Weather Modification - Doc Type: Report

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estimated using the technique described by Paluch (1979). The potential

for the formation of penetrative downdrafts, via mixing of

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environmental air through cloud top and evaporative cooling, was

addressed using the potential buoyancy plots found in Cooper et al.

(1982b,c) . These diagrams used composite aircraft soundings near the

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target cloud to assess the maximum negative buoyancy possible from

mixing cloudy air (containing adiabatic liquid water content) with

envirorunental air until all of the cloud liquid water was evaporated.

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Fig. 2.15 is a composite of the maximum negative buoyancies for the

20 HIPLEX-l clouds. Also shown is a representative temperature scale

and the adiabatic liquid water content assuming a cloud base pressure
of 700 rob and temperature of 30C. The data in this figure show that a

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strong potential for the formation of negative buoyancy exists in
200

300

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400

:0
E 500
w
a:: 600
:J
U)
U)
w
a:: 700
a.
800
900
1000
-4 -2 0 2 4

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T-Tenv (OC)

LIQUID WATER CONTENT (g/m&)
Fig. 2.15: Composite of the potential negative buoyancy plots for the 20
HIPLEX-l clouds. The minimum potential buoyancy results from mixing of
the adiabatic parcel with envirorunental air at the indicated altitude
in the proportion required to just evaporate the liquid water in the
cloud parcel. A representative envirornnental temperature scale is
shown, and the adiabatic liquid water content expected for cloud base
pressure of 700 rob and temperature of +30C is also plotted (LWCAD).

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