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HgUfte 4. A MOW Mmple eo nJ.,iJ.,Ung 06 J.>now6lakeJ.> which tftoke up a6teft ~g the gftound. See denciJtilic ftemenant.6 and J.>now gflaA.nJ.> Oft &uJ.>teM 06 6ftozen dftOplw; J.>cale ,in /mI. F-<-gUfte 5. Figufte 6. Rimed MOW c.ftYJ.>talJ.>. Stic.e 06 thic.Im~J.> O. 3 mm thftough the aUf.> 06 Gl c.onic.al gftaUpel. Th{~ daftk afteM ftepftu ent aift c.apillafti~ within the ice 6ftamewoftk 06 the gftaupel. - 23 - droplets are instantly coverted into precip- itation sized particles which can grow further along the warm rain process, freeze when lifted to sufficiently high levels in the cloud or be captured by growing hail- stones. For non-rotating hailstones other types of shedding will produce droplets which are not too much different in size from the cloud droplets. Shedding of large drops is also indicated when falling hail passes through a warm (> OOC) environment, where the smaller ice particles may even melt com- pletely. 5. Parameterizations The study of ice particles shapes reveals many possible modes of free fall. Thus, it should also be expected that growth would be greatly affected by their fall behavior, firstly through the inhomogeneities in accretion, secondly through the differen- cies in heat and mass molecular transfers. A further complicating factor is the total heat exchange because it determines - given a free fall mode - the character of the particle surface. This in time will control the fate of collected droplets through their potential for accretion or any type of shedding. It must be started at this time that the growth equations for ice particles are not sufficiently known and that every new experiment reveals a new aspect which should also be considered in a reasonably adequate model. This inadequacy of treatment of single particle growth is equally applicable to particle ensembles where interaction terms alter the ensemble behavior (List and Clark, 1973) and control fall times, zone spreading, precipitation rates, etc. Parameterization means analytical description of physical processes, hopefully in very simplistic but nevertheless reason- ably representative fashion. It is the opinion of the author, that the only useful scheme up to this day has been the parameterization of rain formation as introduced by Kessler (1969) in the late nineteen fiftees. He considered three types of water substances in a rain cloud: Water vapor, cloud water and precipitation, and their conservation and conversion. While following physical laws in most cases he boldly stated that the rain is started and continuously created by a conversion function which transforms cloud water int~ precipitation once a threshold amount of cloud water (0.5 gm",3 or higher) is surpassed in a cloud. Raindrops once they are produced continue to grow by collection of cloud droplets.