Convective snow clouds over the Sea of Japan were observed with hydrometeor videosondes (HYVIS), hydrometeor video dropsondes (HYDROS), Doppler radars and a microwave radiometer in four winter seasons from 1989 through 1992. This paper describes the evolution of microphysical structures in short-lived convective snow clouds with a cloud top temperature of -20°C ±3°C, based on a composite of separate snow clouds at various stages. At developing stages, moderate updraft (w
max=∼4 m s
-1) produced a high concentration of supercooled cloud water (close to the adiabatic liquid water content) throughout a cloud. Number concentrations of ice crystals (d < 200 μm) were about 10 particles L
-1 and few precipitation particles (snow and graupel ; d &ge ; 200 μm) were present. At mature stages, the maximum ice crystal concentrations sometimes exceeded 100 particles L
-1 and concentrations of precipitation particles consisting of graupel and heavily rimed snow crystals were ∼10 particles L
-1. These solid particles depleted a material amount of supercooled cloud water through depositional and accretional growth. By decaying stages, almost all supercooled cloud water had been depleted by snow and graupel particles. Only unrimed and lightly rimed snow crystals were still suspended in upper and middle layers. Ice crystals, especially isometric ones such as thick plates and columns, initiated in coexistence with supercooled cloud water (a likely nucleation mechanism is the freezing of cloud droplets), continue depositional and accretional growth and finally produce graupel particles. On the other hand, supercooled and frozen drops were also found in snow clouds at developing and mature stages, which suggests that the warm rain process (precipitation formation through collision and coalescence among cloud droplets) also operates and frozen drops serve as graupel embryos, although these contributions are considered to be small because of low concentration of such drops and their spatially and temporally limited distributions in snow clouds. The cloud water budgets are computed and indicate that, at the developing stage, excess vapor production due to adiabatic ascent of air parcels is predominant and cloud water contents in snow clouds become close to adiabatic values. However, once precipitation is well developed (at the mature stage), clouds (even with an updraft velocity of 1 m s
-1) can not maintain a steady (equilibrium) state and precipitation particles quickly deplete the cloud water through their depositional and accretional growth.
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