WMOD00299

• Title: Physical Structure of Northern Colorado River Basin Cloud Systems
• Date: 9/1/1985
• State: CO
• Weather Modification - Doc Type: Report

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evaluated uSing statistical techniques to determine the probability that

a seeding effect occurred during the experiment. The data are normally

stratified according to meteorological partitions which hopefully relate

to some physical process associated with cloud system structure.

Control stations and covariates are often utilized to strengthen the

statistical analyses. Examples of statistical experiments which have

been conducted in the western United States include the Climax

experiments (Mielke et al., 1971, 1981), the Colorado River Basin Pilot

Project (Elliott et al., 1978), and the Bridger Range experiment (Super

and Heimbach, 1983).

The second method of analysis is through direct measurement of

physical parameters. This method is logistically very difficult,

especially in mountainous regions, particularly if one attempts to

follow the complete process from nucleation to precipitation. In this

method, case studies are developed and eventually generalized into a

conceptual model of the chain of events which lead to the change in

precipitation. Examples of such programs include the Park Range

Atmospheric Water Resources Program (Rhea et al., 1969), the Cascade

Atmospheric Water Resources Program (Hobbs, 1975b), and the Sierra

Cooperative Pilot Project (Reynolds, 1984).

The third method of analysis and interpretation is to utilize

numerical models of the cloud system. If properly modeled, this

technique can be used to evaluate the relative roles of many of the

physical processes leading to the development of natural and

artificially induced precipitation. The words "properly modeled"

carry heavy weight. Examples of such modelling attempts include the work