Laserfiche WebLink
<br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />.' <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />Weather Service (NWS) serv~ce A and seI'v~ce C information and NAFAX <br /> <br />synoptic charts on current and forecast weather, GOES satellite ~magery <br /> <br />showing cloud coverage, structure and temperature, research program <br /> <br />rawinsonde launches from Adamsville about 14 km west-southwest of <br /> <br />Beaver, regular NWS rawinsonde launche s from Salt Lake City, Utah and <br /> <br />Ely, Nevada, and from the State of Utah/NAWC weather observer network. <br /> <br />Data from these sources were compared against the following seeding cr~- <br /> <br />teria (Swart and Griffith (1983) and Thompson and Griffith (1983)): <br /> <br />1) cloud top temperatures are colder than -lOC and warmer than <br />-30C, <br /> <br />2) <br /> <br />the -5C height ~s low enough (at or below mountain crest <br />height) to ensure silver iodide activation as an ice nucleus <br />upwind of the crest, and cloud base height is at or below the <br />mountain crest, and <br /> <br />3) <br /> <br />wind speeds normal to the mountain range are such that addi- <br />tional ice crystals produced through cloud seeding will not <br />blow beyond the target area and evaporate. <br /> <br />According to Swart and Griffith (1983) the first criterion excludes <br /> <br />those clouds with tops warmer than -lOC bE~cause such clouds are believed <br /> <br />to be either too warm for efficient production of additional ~ce <br /> <br />crystals by seeding or else too shallow for sweep-out of significant <br /> <br />amounts of supercooled water by the additional ice crystals. <br /> <br />Clouds <br /> <br />with tops colder than -30C are excluded because it ii believed that ~ce <br /> <br />nucleation, ~ce crystal production, and precipitation (snowfall) are <br /> <br />already naturally efficient. <br /> <br />Seeding these clouds would produce an <br /> <br />excessive number of ice crystals and reduce their precipitation effi- <br /> <br />c~ency. <br /> <br />Within the range of clouds with top temperatures from -lOC to <br /> <br />-30C it is believed that those with warmer tops would be the better can- <br /> <br />didates for precipitation augmentation. <br /> <br />-13- <br /> <br />..i. <br />