Water-phase dynamics in winter snowstorms as observed by microwave profiling radiometry and vertically-pointing radar

Dynamic exchange among water solid, liquid and vapor phases determines the evolution of cloud and precipitation particles in the atmosphere. This work presents observations of water phase dynamics that demonstrates the theoretical Wegener-Bergeron-Findeisen concepts in mixed-phase winter-cloud systems. For this, the work analyzes vertical profiles of temperature, relative humidity, vapor density, and cloud liquid-water content. All profiles were simultaneously retrieved during two snow storms, using two distinct microwave profiling radiometers operating in different climatic regions (North American Central High Plains and Great Lakes). To corroborate our analyses, we use reflectivity factor and Doppler velocity observations by vertically-pointing radars located near the radiometers. Based only on the magnitude ranking of in-cloud vapor pressures and equilibrium vapor pressures over liquid water and over ice, we identified conditions where liquid droplets and ice particles grow or deplete simultaneously, as well as the conditions where droplets evaporate and ice particles grow by vapor diffusion.