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. 2 . Acquiring accurate knowledge of the microphysics of ice crystal growth has been rather difficult. A part of the problem is the inability of the theory to accurately predict factors such as shape and apparent density that profoundly affect the process. Even if such factors are described by known functions of variables such as time and temperature, the aerodynamic feedbacks are not well - understood. For instance, many cloud physicists know that the drag force works against a falling plate differently from that of a sphere and ,thus, ice crystal shape partially controls the fall behavior. However, no general equation or factor exists that accounts for the shape: Pruppacher and Klett (1978) have separate Best number to Reynolds number relationships for spheres, plates and disks. Thus, such effects of the shape stand unclear, and the experimental approach has to be applied to obtain the necessary infromation instead. A much greater problem concerning the studies of growing ice crystals has arisen from the difficulty of obtaining accurate experimental data under conditions simulating natural environment. Until recently, no quantitative data sets for ice crystal growth have been available. Field studies have taken place, but fundamental drawbacks persist. During ground observations of natural ice crystals such as those conducted by Hallett (1965), Auer and Veal (1970) and Mason (1971), ice crystals were collected aner measuring the fall velocity and put under a microscope to determine their dimension. Finally, the crystal was melted to determine its mass. However, the lack of knowledge of the atmospheric conditions and the growth behavior coupled with the inability to control or change the particle's environment seriously weakens the usefulness of such observations. . . . . . . . . .