WMOD00376

• Contract/Permit #: 14-06-D-5640
• Project Name: Park Range Atmospheric Water Resources Program
• Title: Park Range Atmospheric Water Resources Program - Phase II - Parts A and B
• Date: 10/6/1967
• Weather Modification - Doc Type: Report

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There doesn't appear to be any relationship between the total spec-
tral energy of wind direction and the 8000-10,000 foot MSL lapse rate

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measured at Mt. Harris.

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As for the spectra of wind speed, there is a trend towards in-
creasing total spectral energy with increasing instability. The proportion
of energy in the lower and higher frequencies does not appear to change
with changes in stability. The se results are summarized in Table II and
typical spectra for a stable and an unstable case are presented in Figures

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9 and 10.

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COMPARISON BETWEEN ZnS AND AgI PLUMES

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The output of the zinc sulfide aerosol generator in particles per
second is considerably less (2 x 1010) than the output of the silver iodide
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generators (4 x 10 ) used. The zinc sulfide real time sampler is a fast
response unit, the limiting factor being the response of the pen recorder
(a time constant of about a half second). The nucleus counter has a fairly
slow response because of its high-volume cold chamber. It has a pure de.-
lay, for crystal growth, time constant of 30 seconds, a charging time
constant of approximately 30 seconds and a discharge time constant of
120 seconds. This delays indicated peak values and makes the measured
peak concentration approximately half of the instantaneous concentration.

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Typical comparisons of signals along passes through a plume are

shown in Figures 11 and 12. These are tracks from Daisy XLI on 15

February 1967 and are 1 and 2 nautical mile s south of the release site,

respectively. The zinc sulfide unit shows the detailed structure of the

plume and the nucleus counter, allowing for the appropriate time constants,

de sc ribe s the envelope of trace l' mate rial. The ordinate scale s shown

are relative and are not comparable in particles per unit volume.

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The nucleus counte r essentially counts single particles and thus
has a sensitivity threshold governed, in this application, by the background

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