WMOD00298

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

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an indicator of water supersaturation within cloud will not be realized

without further technological developments. It is unfortunate that the

cloud physics field lacks an instrument to measure this most important

quantity, particularly as it influences ice nucleation. Without such a

measurement, it was necessary in this study to estimate supersaturation

using numerical model techniques, as discussed in the following

chapters. The primary uses of the normal humidity measurements are to

set initial experimental conditions and anticipate the onset time of

cloud formation.

Temperature is measured continuously using an array of ten copper-

Constantan thermocouples (0.508 mm wire) located on the inner liner and

two faster response (0.0254 mm wire) thermocouples (TAl, TA2 in Figure

3.1) located 25 cm into the air volume from the inner wall. Temperature

uncertainty is 0.20C. Pressure is measured with strain guage type

transducers. The Setra transducer included with the infrared hygrometer

served as the primary indicator for experiments. Sensitivity is 0.5 mb
at roam pressure (-850 mb).

Two APPLE II computers are used to control expansion, to set the

coolant flow rate, and to control the acquisition. display and

recording of measurements of cloud and wall temperatures, pressure,

humidity, cloud drop concentration, liquid water content, and ice

crystal formation. Selected real-time printed data are generated and

all data are stored on floppy disks. A COMMODORE 64 computer is

separately devoted to the acquisition, real time display and recording

of cloud droplet size and concentration data from the FSSP. Data

analyses are performed on an NCR PC-8, with the aid of special PASCAL