Aggregate Terminal Velocity/Temperature Relations

Abstract

Terminal velocities of snow aggregates in storms along the Front Range in eastern Colorado are examined with a ground-based two-dimensional video disdrometer. Power-law relationships for particles having equivalent volume diameters of 0.5?20 mm are computed for the temperatures ?1°, ?5°, and ?10°C. Fall speeds increase with temperature. Comparison with relationships found in the literature suggests that temperature-dependent relations may be surrogates for relations based on aggregate composition (e.g., plates, columns, or dendrites) and the degree of riming.