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Last modified
7/28/2009 2:39:48 PM
Creation date
4/23/2008 11:59:03 AM
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Weather Modification
Title
Southwest Drought Research Program - Final Report
Date
9/1/1983
Weather Modification - Doc Type
Report
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<br />fires to increase the vertical motions that produce rain clouds; shooting a <br />volume of water into the air to free the atmospheric electricity, thought to <br />be involved in rain development; releasing chemicals such as liquid carbon <br />dioxide into the atmosphere to chill the air; and detonating explosives so <br />that the concussion would condense the rain clouds. Some of these ideas were <br />based on scientific theory and observation, but none was based on a complete <br />understanding of atmospheric processes. <br /> <br />In the 1930's, scientists in Europe found that the growth of ice crystals in <br />the presence of supercooled water droplets (liquid colder than 0 OC) was the <br />key element in one of the two major precipitation processes. In 1946, <br />Dr. Vincent J. Schaefer inadvet'tently discovered that dry ice caused the <br />formation of ice crystals in miniature supercooled clouds which he formed in <br />an ordinary home freezer. He then took his experiment outdoors and found <br />that cloud characteristics changed dramatically when dry ice pellets were <br />dropped into them. Shortly thereafter, Dr. Bernard Vonnegut showed that <br />microscopic silver iodide crystals were more efficient in nucleating ice <br />crystals than the ice nuclei ordinarily found in the atmosphere. Since then, <br />a number of other chemicals have been proven to be effective as freezing <br />nuclei, but dry ice and silver iodide remain the dominant cloud seeding <br />agents. <br /> <br />To help combat drought and secure additional water supplies in arid regions, <br />the Congress began a weather modification program within Reclamation in <br />1962. 1/ IIProject Skywater,1I as this program was termed, has continued to <br />develop means of increasing precipitation from summer and winter clouds. It <br />also includes studies of the economic, social, and environmental aspects of <br />its use and it provides assistance to States in planning and implementing <br />their own operational programs. Figure 1 shows the locations of the major <br />Reclamation weather modification projects of the past 20 years. <br /> <br />1/ Senate Report No. 1097, 87th Congress, 1st Session, September 30, 1961, <br />pp. 28-29 (FY 1962). <br /> <br />5 <br /> <br /> <br />~ <br />/' <br />/' <br />
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