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Miller, J. R., Jr., 1984: Seeding results favor small clouds in China, South Dakota, and Yugoslavia. Journal of Weather Modification, 16:27-29. A comparison of four cloud seeding projects on three continents indicates that smaller clouds may give much greater percentage increases in rainfall than do larger ones in weather modification efforts. Project Cloud Catcher, a randomized single-cloud project in South Dakota 1969-1970, is compared here to a randomized two-area project in Fugian province, China, 1975, 1977, 1981. Also compared are rainfall results from two non-randomized, hail suppression efforts in South Dakota, '1972-1976, and in Serbia, Yugoslavia, 1970-1979. Miller, J. R., Jr., S. Ionescu-Niscov, D. L. Priegnitz, A. A. Doneaud, J. H. Hirsch, and P. L. Smith, 1983: Development of physical evaluation techniques for the North Dakota Cloud Modification Project. Journal of Weather Modification, 15:34-39. This paper is a summary progress report on the development of physical evaluation techniques aimed at assessing the effects of ice phase cloud seeding on summertime convective stonns in North Dakota. The use of digitized 5-cm radar data, rawinsonde data, and one-dimensional cloud model results are discussed in this techniques development effort. These preliminary results suggest favorable tendencies toward successful rainfall enhancement. Various biases are presented and suggestions for further research are made. Mitchell~ D. L., 1991: Evolution of snow-size spectra in cyclonic stonns. Part II: Deviations from the exponential fonn. Journal of the Atmospheric Sciences, 48: 1885-1889. Using a fonn of the stochastic collection equation, conservation equations for the first and second moments of the mass were parameterized to yield a height-dependent one-dimensional snow growth model for unrimed stratifonn snowfall. Snow-size distributions were represented by the fonn N(D)= NoDVexp(-')..D), and solutions for').. and No were obtained. The spectral parameter v allows the concentration of the smaller ice particles to deviate from the exponential fonn and controls the degree of subexponential or superexponential behavior. The sub- and superexponential spectra analyzed in this study had v values of 1 and -1, respectively. A number of simple analytical relationships was developed that describes various properties of size distributions, regardless of the particle type involved. A method was developed for obtaining the three parameters of the size distribution used in the model from measured size distributions. In addition, an expression was derived to relate the two ').. of an exponentially parameterized and a nonexponentially parameterized size distribution. The effect of sub- and superexponential spectra on the evolution of snow-size spectra by vapor diffusion and aggregation was examined using a steady-state, fixed snowfall rate profIle. Diffusional growth rates of individual ice crystals (no aggregates) were relatively low when the size distribution was constrained to be superexponential in fonn. This resulted in steeper spectra (smaller crystal sizes) and higher ice- crystal number concentrations. The diffusional growth rate of individual ice crystals for subexponential spectra was relatively high. Subexponential spectra were characterized by broader distributions and lower ice crystal number concentrations. Aggregation was the only growth process that substantially increased ice particle sizes for superexponential spectra, while both vapor diffusion (in the upper cloud) and aggregation (in the mid-to-Iower cloud)' contributed substantially to size increases for subexponential spectra 52