WMOD00400

• Contract/Permit #: 14-06-D-6801
• Title: Structure and Seedability of San Juan Storms
• Date: 11/1/1976
• Weather Modification - Doc Type: Report

39

until shortly before the flight, the storm period was assumed to be seeded.

Note that classification of a storm period as seeded means that we

expect to find AgI some,vhere in the clouds; the AgI does not necessarily

have an effect on the precipitation at that time. For example, these

criteria predict that the first flight on 29 December 1974 was during a

seeded storm period. In fact \ve did find seeding material during our first

flight in that storm, but not in regions where the high ice crystal concen-

trations originated (see section V.A.3.h).

These classification criteria were applied by one of us (J.D.~I.)

in constructing the predictions of the following table (3.1). Another

of us (Iv.A.C.) examined the ice nucleus data, and classified the storm

periods as indicated in the "AgI detected" column. Storms in \vhich an ice

nucleus concentration greater than 0.5 per liter was detected (at -19C) were

classified as seeded. The final column lists the classification used according

to the criteria of the Colorado River Basin Pilot Project.

Table 3.1

Date Seed Prediction "AgI" Detected? CRBPP Classification
29 DEC III Yes, carryover Yes No
29 DEC 112 No No No
29 JAN III No, stable No Yes
29 JAN 112 Yes Yes Yes
30 JAN f.!1 No, stable No No
30 JAN f!2 No No No
17 HAR No No No
21 MAR Yes No Yes
22 MAR III Yes, carryover Yes No
22 MAR 112 No No No

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