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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 />1- <br /> <br />40 <br /> <br />In only one case, 21 March 1975, do the observed seeding characteristics <br /> <br />disagree with our predictions. Unfortunately, our failure to detect seeding <br /> <br />material on this date, during an unstable period when the generators \vere <br /> <br />operating, casts doubt on the validity of these measur~lents. We do not have <br /> <br />an explanation for this discrepancy, except that perhaps we missed the region <br /> <br />where the AgI \vas being carried. It is notevlOrthy that most of the ice <br /> <br />nucleus ground network operated by WSSI also detected negligible nucleus <br /> <br />concentrations during our flight times (Hartzel et a1. 1975). Also no <br /> <br />convergence zone was present during this flight to aid the vertical trans- <br /> <br />port of AgI. <br />Notice that our prediction disagrees with the CRBPP classification on <br /> <br />three out of ten cases. The actual observations disagree on four of ten <br /> <br />cases, but one of those is the questionable 21 Harch 1975 cases. This is <br /> <br />an indication that the original stratification in the San Juan Project was <br /> <br />frequently in error, because of the poor diffusion of AgI in stable situa- <br /> <br />tions and because of carryover seeding. <br /> <br />Host of the filter samples ~vere obtained in-cloud. Because of the <br /> <br />rapid scavenging of AgI in-cloud (discussed later in this section), most <br /> <br />of the AgI \vas probably in the cloud ,vater or in. ice particles. A sample <br /> <br />of the cloud, including \Vater and ice, was dra,VD through the filters. The <br /> <br />air warmed sufficiently in passing into the cabin of the aircraft so that <br /> <br />the cloud \Vater evapo}~ated before reaching the filters. Thus the sample <br /> <br />collected consisted of the particles in the air and all the residue left <br /> <br />when the droplets evaporated. If the droplets contained AgI, either in <br /> <br />dissolved form or as particles, this AgI would be collected on the filters. <br /> <br />In this I-laY Ive were apparently able to detect the AgI even in-cloud. How- <br /> <br />ever, the results should not be interpreted as actual ice nuc.leus <br />