WMOD00453

• Project Name: Park Range Atmospheric Water Resources Program
• Title: Park Range Atmospheric Water Resources Program - Phase I
• Date: 1/1/1967
• Weather Modification - Doc Type: Report

14

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Figure l4.-Mobile Ground.based ZnS Detector.

able cost if the real-time sampling technique had
not been available.
The only anomaly in equipment operation is that
ZnS particles will collect in the inlet tube and ir-
radiating chamber over a period of time and then
flake off during test runs. It does not take much
experience with the equipment to tell when this
effect is occurring, and the trace produced is dis-
tinctly different from a true plume trace. If one
were doing precise quantitative research work, he
might take great pains to clean the equipment; in
our field operation this was not possible and we
learned to live with the anomaly.

Figure 15.-Airbome ZnS Detector Equipment-Redundant
Installation.

PARK RANGE ATMOSPHERIC WATER RESOURCES PROGRAM

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Figure 16.-ZnS Aerosol Generator.

To determine the concentration of ZnS tracer in
snowmelt samples, we developed the laboratory in-
strument shown in figure 18. It has the essential ele-
ments of the mobile ZnS detection equipment, ex-
cept that the sample is liquid in a test tube and the
light maze is a spinning reticle that alternately
exposes the sample to UV radiation and then stops
off the light and exposes the photomultiplier tube
face to the phosphorescing sample.
The device has a dynamic range of about 105,
operates entirely from 1I0 volts a.c. and produces
stable, repeatable results. The photomultiplier tube
output is displayed on a calibrated oscilloscope.
With snow samples taken after diffusion tests, we
are able to confirm the horizontal dimensions of
the plume-as determined by the mobile detectors-
and fall-out characteristics.
Snowcrystal replicas were made during each
storm to have a record of snowcrystal types, and for
possible use in nuclei analysis. The 1 percent form-
var in ethylene dichloride technique was used and
the replicas air-dried.