Measurements of the heat and mass transfer parameters characterizing conical graupel growth

Abstract

Rigidly suspended conical graupel were grown in a wind tunnel: growth conditions were chosen to simulate natural conditions in which conical graupel grow and serve an embryos for hail. Final graupel diameters ranged from 1.5 to 6 mm, with Reynolds numbers between 300 and 1500. Measurements of the mass, volume, growth height, geometric shape, and surface temperature with time were used to calculate the Nusselt and Sherwood numbers (representing the convective heat and mass transfers), bulk collection efficiency, and accretion density. The bulk collection efficiency was found to be 25% lower than that for ideal smooth spheres, while the Nusselt numbers were approximately 50% higher than those of smooth cones. The enhanced heat convection and mass deposition or sublimation is attributed to the roughness of the ice surface. -from Authors