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<br />l <br />l <br />\ <br />) <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />! <br />I <br />I <br />I <br />) <br /> <br />3.0 NAWC ORGANIZATION AND FACILITIFS <br /> <br />NAWC was acquired by TRC Companies in 1992. NAWC operates as a <br />subsidiary of TRC Environmental Corporation. NA WC's main office is located at 1293 <br />West 2200 South, Salt Lake City, Utah. It was from this office that staff meteorologists <br />monitored weather conditions and provided guidance to the NCWCD on when to operate <br />the Cloud Nuclei Generators (CNG) during weather events that offered the best <br />likelihood of precipitation augmentation for the target area. <br />'- <br /> <br />3.1 Field Rauioment and Locations <br /> <br />The primary seeding system used during this program was a network of ground <br />based CNG's. Each CNG consists of: 1) a reservoir (tank) and its enclosing frame, <br />which holds the seeding solution that is pressurized to approximately seven psi by <br />propane, 2) a flowmeter which regulates consumption of the seeding solution, 3) a bum <br />chamber where the solution is burned in a propane flame, and 4) a wind screen which <br />shields the bum chamber from excessive winds. <br /> <br />The CNG units were designed and assembled by NAWC, and are owned by the <br />NCWCD. The efficiency of the CNG to produce AgI ice nuclei is shown in Figure 3.1. <br />This figure shows the results of recent independent testing perfonned at the Colorado <br />State University cloud simulation laboratory (DeMott, 1994). The figure clearly <br />indicates the dependency of nuclei production on temperature with considerably more <br />effective nuclei produced at colder temperatures. This tremendous output of nuclei in <br />the -50C to -150C temperature range, the range in which most clouds are generally <br />lacking nuclei, can make natural clouds more efficient in converting the available <br />supercooled liquid water into ice crystals. <br /> <br />The CNG equipment setup is illustrated in Figure 3.2. Installation is quick and <br />relatively simple. It consists of setting the CNG unit on a flat surface in an open area, <br />then anchoring it for stability in windy conditions. A propane line is then run from the <br />CNG to a nearby propane tank. <br /> <br />., 1 <br />