WMOD00155

• Contract/Permit #: #94-6
• Applicant: North American Weather
• Project Name: Willow Creek Basin
• Date: 11/1/1993
• Weather Modification - Doc Type: Report

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3.0 NAWC FACILITIES

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NAWC's main office is located at 1293 West 2200 South, Salt Lake City, Utah.
It was from this office that staff meteorologists monitored weather conditions and
provided guidance to the NCWCD on when to operate the Cloud Nuclei Generators
(CNG) during weather events that offered the best likelihood of precipitation
augmentation for the target area.

3.1 Field EQuiDment and Locations

The primary equipment used during this program was ground based CNG's. This
equipment consists of: 1) a reservoir (tank) and its enclosing frame, which holds the
seeding solution that is pressurized to approximately seven (7) psi by propane, 2) a
flowmeter where the consumption of the solution is regulated, 3) a bum chamber where
the solution is burned in a propane flame, and 4) a wind screen which shields the bum
chamber from excessive winds.

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The CNG units were designed and assembled by NA we, and are owned by the
NCWCD. The efficiency of the CNG to produce AgI ice nuclei is shown in Figure 3.1.
This figure shows the results of independent testing performed at the Colorado State
University cloud simulation laboratory (Finnegan, 1982). The figure clearly indicates
the dependency of nuclei production on temperature with considerably more effective
nuclei produced at colder temperatures. This tremendous output of nuclei in the -50C
to -150C temperature range, in which most clouds are generally lacking nuclei, can make
natural clouds more efficient in converting the available supercooled liquid water into ice
crystals.

The equipment setup is illustrated in Figure 3.2. Installation is quick and
relatively simple. It consists of setting the CNG unit on a flat surface in an open area.
Then anchoring it to keep the unit from tipping in case of extreme wind. A propane line
is then run from the CNG to a nearby propane tank.

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