Laserfiche WebLink
<br />seeding agent into the supercooled part of a cloud to promote the <br />rapid conversion of water droplets into ice crystals. When this <br />water-to-ice conversion process occurs rapidly,. latent heat of <br />fusion is released from water droplets on a massive scale which <br />makes the cloud slightly warmer and more buoyant. The updraft then <br />becomes invigorated and draws in greater amounts of water vapor to <br />supply more moisture for cloud growth and "processing" into <br />rainfall. This enables the seeded cloud to produce more rain for a <br />longer time than if unseeded. <br /> <br />Although silver iodide produces greater numbers of ice nuclei <br />than does dry ice, gram for gram, large numbers of ice nuclei can <br />be produced more quickly by dry ice. Relatively large amounts of <br />dry ice are needed to produce an equivalent number of ice crystals <br />from a given mass of silver iodide, roughly lOOO to 2000 grams dry <br />ice to one gram silver iodide. Cloud droplets in contact with dry <br />ice falling through clouds or brought into its wake immedia"Cely <br />convert to ice crystals, whereas, silver iodide only starts to <br />activate at temperatures below -5C---about 1,500 to 3,000 feet <br />above the freezing level and more actively at higher altitudes. <br /> <br />Dry ice is dispensed from a hopper auguring dry ice into an <br />opening in the aircraft floor which allows the dry ice to fall into <br />the clouds. The hopper carries 200 Ibs of pelletized dry ice and <br />automatically releases dry ice at a rate of 5 Ibs per minute. <br /> <br />Dispensing ejectable silver iodide flares at cloud top is more <br />expensive than dry ice because they have to be manufactured. The <br />cost .of using silver iodide at cloud top to get equal ice crystal <br />nucleation is presently greater than the cost of dry ice despite <br />the dry ice losses due to sublimation before it gets dispensed. <br /> <br />The cloud'systems listed below, and variations of them, are <br />most responsible for producing rain and hail in Western Kansas: <br /> <br />(1) air-mass storm complex <br /> <br />(2) multiple celled storms <br />(3) squall line <br /> <br />Air-mass storms usually become complex after starting as an <br />isolated cloud system having a well-organized cloud base with its <br />updraft area dipping below that base. Multiple cells often develop <br />on the initial storm and storm movements can become variable <br />depending upon several factors, among them terrain effects, dynamic <br />factors within the storm, cloud height and variability of wind <br />speed and direction with height. <br /> <br />Air-mass complexes often transition into a large, multi-celled <br />storm systems. Fig. 2 shows a "classic" storm with new growth on <br />its left side. Drawing a line through the center of precipitation <br /> <br />9 <br />