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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 />23 <br /> <br />ohanging the final equilibrium or product and is not destroyed (Berry, <br />et al., 1980). <br /> <br />The chemical kinetic methodology in the study of heterogeneous ioe <br /> <br />nucleation was demonstrated by DeMott (1'82) and DeMott. et ale (1'83). <br />They utilized hydrophobic AgI and AgI-AgCl aerosol partioles and <br /> <br />observed the decay of the aerosol partiole population with time after <br /> <br />injeotion into a large mixing oloud chamber. <br /> <br />DeMott (1'82) and DeMott, et ale (1'83) present a full outline of <br /> <br />the possible meohanisms of heterogeneous ioe nucleation by aerosol <br /> <br />partioles, inoluding vapor deposition, condensation to embryos followed <br /> <br />by treezing, oondensation to droplets followed by freezing, and contaot <br /> <br />freezing. Each process is described with a chemical reaction equation <br /> <br />of the form A+~C-+-D. Rate expressions are given for the slowest, or <br /> <br />rate determining step whioh they aBsess is the nuoleation prooess <br /> <br />itself. Tw~ b~iO__f!Quations,"~~...~~~ven'd.~e rate ot disappearen~~~_ of <br />ioe nuclei is proportional to the concentratio~ of nuclei 8Il~Lwater <br /> <br />----~".._. -'--' - -_.. --.------------- <br /> <br />vapor tor the case of vapor deposition andoondensa~iOll free;1ng. For <br />~"".--.."'?~......".......,--~ ~"-.~~.--_.~-~-~_.~ - -~ <br /> <br />contaot ioe nuoleation, the rate is proportiona~_~~.the oonc~ntrations <br /> <br />of nuolei and cloud droplets. The authors prooeed to demonstrate that <br /> <br />~...~.,.__o_~=--_ . ,__,,~.-.c"';:" .-""~-C" _.____~_.__~ <br /> <br />fo!"hydrophobio ice nuolei, functioning by the contact mechanism, the <br /> <br />",rate sigD!fioan~~l!ifte~fJ the }~n~ntration of cloud dr:o.P;~~s_!.~s <br />altered. The proportionality constant for the rate was determined. The <br /> <br />measured values agree_dfavorabl~_!!~~ theoretical val\les fQl'Br.owni~1L <br />- - - .-~ <br /> <br />ooagulat~orLof ae~_,?_~()~ partiole_~_ to clo~.~ drol'_~f!ts. <br />Chemioal kinetios in the study of ice nucleation differs in a <br /> <br />number of ways from past methods used. The time factor in ice <br /> <br />nuoleation was first noted by Vonnegut (1949) when he observed the <br /> <br />