WMOD00298

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

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

37

and FORTRAN 77 programs and a statistical graphics package, after data

are converted to compatible ASCII formats and transfered through one of

the CSU CYBER 206' s. A new data system based about a single 386 PC

machine will soon replace the old data system (DeMott and Rogers,

1990). Improvements in ice detection systems will also be made.

3.2 Isothermal Cloud Chamber
The CSU isothermal cloud chamber (ICC) has been described
previously by Garvey (1975), and DeMott et al. (1983). The chamber is a
closed cylindrical double shell with an inner shell of 0.64 em
aluminum, 1.37 m in diameter and 1.52 m high. The outer shell of 10

gage steel is 1. 68 m in diameter, and the annular space between the

shells is filled with polyurethane insulation. Cooling is achieved by

a two-phase Freon flow in a system of 1.5 cm tubes welded to the

outside of the inner shell at 15 em spacings. These features were

designed to maintain wall temperature within +/- O.l'C around the

chamber walls. The inner shell of the chamber is fitted with a black

velvet liner about. l5 cm from the wa~ls. Originally installed to

minimize frost accumulation and shattering, the liner has proved

important in maintaining an experimental volume with an acceptable

cloud density gradient.
The cloud is introduced using the system shown schematically in

Figure 3.7, from DeMott et al. (1983). Cloud droplets are generated

continuously by the atomization of distilled water with an ultrasonic

humidifier (Monaghan 670). They are then mixed with cold air and

allowed to equilibrate with the chamber while rising through a standing

tube in its center. By varying dilution airflo~, the liquid water