WMOD00509

• Title: Physics of Winter Orographic Precipitation and it's Modification - Summary of Presentations
• Date: 10/1/1985
• Weather Modification - Doc Type: Report

cloud top mixing the dilution eventually reaches down to the
freezing level. This dilution process increases the up and down
motion through the melting level, and as small ice crystals are
continually melted and refrozen the surface water tends to
congregate in blobs with continual thinning of the ice between
them. This process will be particularly effective for very small
ice columns or splinters since surface tension forces dominate at
the smallest sizes. The bigger crystals corne from later growth.
Eventually separation occurs between the blobs and since the
motion of the turbulent cloud carries many of the crystals up
through the -50C level and higher, these ice particles grow
rapidly by sublimation and accretion and the latent heat release
sends them up to cloud top. This suggests that clouds with bases
at the _50C level should more often contain liquid water than the
clouds with bases at temperatures above freezing, and hence be
suitable targets for seeding.

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