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<br />. <br /> <br />4 <br /> <br />. <br /> <br />Despite this lack of data, a few detailed studies of ice crystal growth were <br /> <br /> <br />carried out by numerically simulating the process. Two such investigations <br /> <br /> <br />were carried out by jayaweera (1971) and Miller and Young (1979). An <br /> <br /> <br />example of their results is shown in Fig. 1 where ice crystal mass is plotted as <br /> <br /> <br />a function oE temperature at 10 minutes after nucleation. <br /> <br />The model formulated by jayaweera (1971) employs the Maxwellian <br /> <br /> <br />growth equation with correction factors describing the effects of shape and <br /> <br /> <br />ventilation. The shape effect depends primarily on the axial ratio and the <br /> <br /> <br />data used to determine this ratio were taken from Ono (1970), Mason (1953), <br /> <br /> <br />Nakaya and Terada (1935) and Reynolds (1952). Each of these data sets has at <br /> <br /> <br />least one drawback. Ona performed field experiments in an airplane where <br /> <br /> <br />the captured crystals were damaged by impact. Mason obtained data from a <br /> <br /> <br />cloud chamber that grew crystals in naturally simulated conditions for <br /> <br /> <br />periods only up to 1 or 2 minutes. Nakaya and Terada took field <br /> <br /> <br />measurements of ice crystals whose environmental conditions could not be <br /> <br /> <br />determined. Thus each investigator performed experiments either under <br /> <br /> <br />conditions not necessarily the same as that assumed by the model or for <br /> <br /> <br />crystal growth periods much shorter than that allowed for each model run. <br /> <br /> <br />Miller and Young (1979) improved the model of jayaweera (1971) by <br /> <br /> <br />considering the effect of nearby water droplets and discrete vapor and <br /> <br /> <br />temperature fields, and by using updated data with increased accuracy. The <br /> <br /> <br />fog factor and the diffusion-kinetic effects were theoretically derived by <br /> <br /> <br />Marshall and Langleben (1954) and by Fuchs (1959), respectively. (This <br /> <br /> <br />diffusion-kinetic factor was shown to be in serious error by Fukuta and <br /> <br /> <br />Walter, 1970.) Data provided by various investigators such as Ryan et aJ. <br /> <br /> <br />(1976), who extended the growth time of a suspended crystal in cloud chamber <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br />