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<br />steady-state models to correctly diagnose precipitation (Sax, 1972; <br />Weinstein, 1972b), this study focuses on the model's strength in diagnosis <br />of the dynamic potential for convective cloud growth (Sax, 1969; Marwitz <br />et al., 1970). <br /> <br />b. Model Characteristics <br /> <br />The GPCM is a one-dimens iona 1, steady-state Lagrangi an parcel models imil ar <br />to the Weinstein-Davis model (1968) and modified by Hirsch (1971) to <br />include parameterizations of Berry (1967), Kessler (1969), and Wisner et al. <br />(1972) for microphysical processes of cloud water, rainwater, and cloud <br />ice and graupel formation. Seeding effects are simulated by a linear <br />freezing function for cloud water and rainwater (Squires and Turner, <br />1962). In these experiments natural clouds were gl aciated linearly from <br />-20 to -40 oC with 50 percent of all supercooled water being frozen by <br />-30 oC and 100 percent frozen by -40 oC. Seeded clouds were glaciated <br />linearly from -5 to -25 oC using Saunders' (1957) freezing methods. The <br />limitation of this method of freezing was discussed by Orville and Hubbard <br />(1973). The effect of latent heat changes in the rate of cloud ice and <br />graupel growth was also simulated in the natural and seeded cases using <br />the bulk parameterization of Kessler (1969) and Berry (1967). Model <br />result s us i ng these bul k parameteri zat ions are 1 imi ted by the steady-state <br />assumption for complex time-dependent processes (Cotton, 1972, Wisner <br />et al., 1972) of nucleation, accretio~, aggregation, and other mechanisms <br />which require rapid glaciation. <br /> <br />A series of six different cloud updraft radii were simulated in all mode'l <br />runs. These updraft radii control the amount of entrainment as simulated <br /> <br />9 <br />