WMOD00291

• Title: Bulk Parameterization of the Snow Field in a Cloud Model
• Date: 6/6/1983
• Weather Modification - Doc Type: Report

JUNE 1983

UN, FARLEY AND ORVILLE

1081

CASE 1 i

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CASE 2

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CASE 3

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FIG. 6. (Continued)

Case 1 than in Case 2. THe hail and snow interactions
with the rain field in Case 1 have kept the rain content
less than the threshold atnount for plotting. None of
the precipitating classes :have exceeded the plotting
thresholds in Case 3 at 24 min. The fields of precip-
itating particles (rain, snbw and hail) are cap-shaped
in the cloud, due to the stfonger updraft in the middle
of the cloud. :
At 30 min (Fig. 6a), the cloud has developed to
about 11 km and an anvil is forming in all cases. The
cloud base is at 2 km. Cbnsiderable amounts of rain

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and some hail are reaching the surface at this time
in Cases 1 and 2. Precipitation is appearing in the
upper levels of Case 3 (no autoconversion) with the
maximum of hail showing up on the sides of the main
updraft. For Case 3, the primary generation mecha-
nism for the hail up to this time is aggregation of
snow (PGAUT). The snow, in turn, has grown mainly
by accretion of cloud water.
At 36 min (Fig. 6b), much of the cloud in Cases
1 and 3 contains some snow with virga underneath
the anvil. The cloud in Cases 1 and 2 is in the later