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

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PARK RANGE ATMOSPHERIC WATER RESOURCES PROGRAM

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Figure H.-Laboratory and Sensor Test Area.

figure 13, and the plume tracked by a truck-mounted
sensor, figure 14, and an airborne sensor, figure 15.
The aircraft for these tests was provided by the
National Center for Atmospheric Research in con-
sequence of a mutual interest in the diffusion
results.
Zinc sulphide is a non-toxic compound having
the property that it phosphoresces when irradiated
by ultra-violet energy. The time constant of the
phosphorescence is of the order of a few tenths of a
second. In practice, dispensing begins about 15
minutes before the aircraft arrives for sampling runs
and continues for 1 to 2 hours. The aircraft flies a
race-track pattern through the plume at various
ranges and altitudes to define the plume dimensions.
Once the plume is detected by the aircraft, the truck
unit is dispatched on the nearest possible vector
and attempts to determine: (1) whether fall-out is
occurring in the valley, or (2) the boundary of the

plume on the ground-on the Park Range ridge.
Once one becomes familiar wi th the vagaries of a
particular area, semi-quantitative plume detection
runs become rather simple and routine operations.
Such tests quickly show the pattern of diffusion that
can be expected under various wind and stability
conditions; hence, are valuable indicators of arti-
ficial nuclei dispersion when nucleation operations
are conducted from the same dispensing site.
The ZnS dispensing equipment is shown in figure
16. Liquidized powder is fed manually into a hop-
per and metered automatically into a high velocity
blower. The output aerosol has a mean particle
diameter of about 3JL (JL = 10-6 meters), and
powder emission is 30 Ib.jhr. The unit is powered
by llO volts a.c. and has proven completely reliable
in our tests. Both powder and dispenser were pro-
curred from Metronics, Inc., Palo Alto, Calif.
The real-time sampling equipment used in the