WMOD00306

• Project Name: Sierra Cooperative Pilot Project
• Title: Sierra Cooperative Pilot Project - Operations Plan - 1986-1987
• Date: 10/1/1986
• Weather Modification - Doc Type: Report

for precipitation characterization and for comparison with the aspirated
2D-C, in a size range where the measurements overlap.

The probe will be operated at KGV during experimental units. The data
acquisition system (DAS), formatter, and tape drive will be located in the
radiometer along with the DAS for the 2D-C. This is particularly important
as the DAS for the grey scale probe requires frequent checking since it
occasionally needs to be restarted.

c. Photomicrographs of snow crystals collected in petri dishes will be
used to document crystal habit and degree of riming. Four or five photo-
micrographs will be taken of snow crystals collected at approximately 5-10
minute intervals during operational periods. The photographs will be taken
randomly in an attempt to characterize the snowfall collected. Also a
manual record of the crystal habits and degree of riming will be kept as a
backup in case of loss of the film log. The equipment consists of a
microscope with camera, automatic exposure control unit, and cold stage
attachments. Tri-X black and white film is used. Negatives of the photo-
mi crographs will be contact pri nted into a time seri es format for 1 ater
analysis.

d. Concurrent with the photomicrographs, shadowgraphs will be collected at
5-10 minute intervals. These Polaroid pictures provide a ~rue size snap-
shot of the characteri stics of the preci pitat ion. Each photograph wi 11
represent a 10 second exposure to the snowfall. These observations are
aimed at obtaining a chronology of aggregation, the habit and degree of
riming of the crystals forming the aggregates, and the approximate number
of crystals per aggregate. Additional observations of habit and rime of
unaggregated crystals can be useful as a backup to photomicrograph obser-

III-20

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