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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />The meohanisms, rates, and yields observed in the laboratory are <br /> <br />applied to a theoretioal, physioal and miorophysioal orographio oloud <br /> <br />model to assess the ioe nucleation oharaoteristios of silver iodide- <br /> <br />sodium iodide aerosol partioles in the temporal and spatial soale of an <br /> <br />orographio oloud. Three parameters have been found to control the <br /> <br />_.~-..------~--" ~ ,~. ---.,-----.--. --.----.-..-.---- <br /> <br />extent and looation of ioe nuoleation: 1) nuoleation meohanism, <br />~_._,.~----~---- ---~..._~._------- '- --_,-~-~-<-_._'-'-'-., -~.~---------~- <br /> <br />2)0loud t~~r~t~~. Rnd3) w.:l,mL~. The slower meohanism of <br /> <br />oondensation to droplets followed by freezing, which ooours at slight <br />~....--'''-'' - .... <br /> <br />water saturation, oauses ioe orystalprod1,lotion to be, prol~ngedove!:. <br />"---'-,~'''~.-.-.- ,. <br /> <br />time and spaoe. <br /> <br />Resulting preoipitation oan ooour over large areas. <br /> <br />The faster meohanism of oondensation to aqueous embryos followed by <br /> <br />freezing, whioh ooours in water supersaturated areas of the cloud, <br /> <br />results in ice nucleation primarily within a zone of a few kilometers of <br /> <br />the cloud. Preoipitation would then occur in a limited area on the <br /> <br />surfaoe which would subsequently affect the targeting and analysis of <br /> <br />seeding effects. Temperature influences the yield, or effectivity, and <br /> <br />is mst important for the fast mechanism. Wind speed controls the time <br /> <br />available for nucleation. Application of laboratory determined rates <br /> <br />and mechanisms to various cloud models can be an important tool in the <br /> <br />development of the hypothesis, statistical design, and physical analysis <br /> <br />of experiments and programs that utilize artificial ice nucleants for <br /> <br />weather modification. <br /> <br />Rochelle Rose Blumenstein <br /> <br />Atmospherio Science Department <br />Colorado State Univer1sty <br /> <br />Fort Collins, Colorado 80523 <br /> <br />Spring, 1985 <br /> <br />iv <br /> <br />