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7. The droplet spectra show evidence of a highly inhomogeneous mixing pro- cess, but that mixing did not lead to significant broadening of the droplet spectra during the early evolution of the cloud. 8. The cloud possessed a clear unmixed region, in which the variations in droplet concentration were measurable on 500-1000 m scales but not on smaller scales. The fluctuations were apparently' associated with differences in the updraft speed for various parts of the parcel as it passed through cloud base. Aircraft measurements indicated that the droplet spectrum was bimodal in the unmixed region. This is puzzling, and it is not certain that it is not the result of a problem with the FSSP although nearby spectra were measured to be unimodal. 9. A preliminary hypothesis is that this cloud was basically a "thermal" or "bubble", with inhomogeneous mixing processes characterizing the leading and lateral boundaries of the bubble and homogeneous processes characterizing the trailing boundary. B. HIPLEX - July 22, 1979 Cumulus congestus clouds developed on July 22, 1979 and produced precipitation through the ice phase process. This case was well documented by HIPLEX cloud physics aircraft and radar and has been a subject of intensive analysis by Cooper et ale (1982). It was selected as a case for model simulations of preci- pitation-evaluation because of the complete documentation of microphysical pro- cesses. This was a HIPLEX-1 seeded case, therefore it also offers an opportunity to study seeding processes and the effects of seeding on precipita- tion development. Weather conditions on the morning of July 22 were favorable for the HIPLEX-1 experiment. The 850 mb map featured a surface trough over mid-Montana, and the sounding appeared favorable for the development of convective clouds. The clear skies over eastern Montana permitted good surface heating through the morning. In the late afternoon, a long line of thunderstorms formed along this surface trough, by then over eastern Montana. There were also some airmass towering cumulus in the moist air east of the trough. At takeoff, a storm was located to the south wi th refl ect i vi ty exceedi ng 40 dBl. Towers were also building to the northeast, and looked to be in an earlier stage of development, so that area was selected for study. These clouds were the most vigorous in the area northeast of Miles City. The concentration of droplets was one of the highest in the HIPLEX-1 experiment, 845/cm3 averaged over the 1-km distance with the highest liquid water content. The average liquid water content determined from the FSSP measurements in this regi on was 1.25 g/m3, or about 25% hi gher than that measured by the ,JW probe. The spectrum was relatively narrow, and the concentration of droplets larger than 24 ~m in diameter was only about 1/cm3. The seeding started at 211403Z. During this pass by the Lear at the -10 oc level, a few ice crystals were encountered, but the highest concentration was 13.