WMOD00298

• Title: Quantifying Ice Nucleation by Silver Iodide Aerosols
• Date: 5/1/1990
• State: CO
• Weather Modification - Doc Type: Report

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IV. EXPERIMENTAL DESIGN

4.1 Laboratory Experiments

Development of the laboratory experimental design was in itself a

primary goal and an obstacle for this research program. These types of

studies had never been performed before. The ideal design is described

along with the actual procedures used here, as they were compromised by

the limitations of available physical facilities and time. Ice

nucleation is quantified in the framework of well founded macroscopic

conceptual models of the various processes that can lead to ice

formation. Standard definitions of these have been given in Chapter 2.

Again, it is important to note that this is not a study of the nature

of the different mechanisms, only of their consequences. The

microscopic details related to each mechanism are not well known, but

are not important for this study. The macroscopic details are important

because they help define the experiments necessary to isolate the

contributions of different modes for different atmospheric conditions.

In this regard, the working definitions of the nucleation modes differ

slightly from the standard definitions, and from the definitions given

by DeMott et al. (1983). For example, any nucleation occurring below

water saturation is included as deposition nucleation, since the role

of liquid condensation cannot be discerned. The current definitions are