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.' .. .. -. . . . '. r, .. ',1 Table 1 NA WC Winter Cloud Seeding Criteria , . CLOUD BASES ARE BELOW THE MOUNTAIN BARRIER CREST. . LOW-LEVEL WIND DIRECTIONS AND SPEEDS THAT WOULD FAVOR THE MOVEMENT OF THE SILVER IODIDE PARTICLES FROM THEIR RELEASE POINTS INTO THE INTENDED TARGET AREA. . NO LOW LEVEL ATMOSPHERIC INVERSIONS OR STABLE LAYERS THAT WOULD RESTRICT THE VERTICAL MOVEMENT OF THE SILVER IODIDE PARTICLES FROM THE SURFACE TO AT LEAST THE _50C (230F) LEVEL OR COLDER. . TEMPERA TORE AT MOUNTAIN BARRIER CREST HEIGHT EXPECTED TO BE .seC (230F) OR COLDER. . TEMPERATURE AT THE 700 MB LEVEL (APPROXIMATELY 10,000 FEET) EXPECTED TO BE WARMER THAN -150C (5OF). A network of 18-20 ground based silver iodide generators will be used in the conduct of this project. These generators will be sited at private residences or public places of business. The residents or business operators will be trained in the operational procedures to be used in turning the generators on or off. NA WC meteorologists will contact these operators when conditions have been determined to be favorable for operations and request that the generators be turned on. When conditions are no longer favorable, the operators will be called to turn the generators off. Figure 2 provides a photograph of one ofNA WC's ground based, manually operated units. Each generator site us equipped with a propane tank. The propane is lit within the generators bum chamber and then the silver iodide (dissolved in acetone) is injected into the propane flame. As the effluent from the generator cools, literally trillions of microscopic sized particles of silver iodide are produced. These particles have the ability to cause water droplets within clouds that are colder than approximately _50C to freeze. The tiny ice crystal that is produced, if it remains in 3