An Equivalent Disc for Calculating the Terminal Velocities of Plate-Like Ice Crystals

Abstract

Measurements of terminal velocities of metal models of plate-like ice crystals in a tank containing various concentrations of glycerol in water suggest that the terminal velocities of a given model can be predicted from that of a disc made of the same material having the same mass and thickness. The terminal velocities of the models are less than that of the corresponding disc by a factor determined by the shape of the model. This factor is a maximum at 25% for the star-shaped model. These results are independent of the material of the disc or liquid and cover a Reynolds number range of at least 0.5 to 200; they are therefore applicable to plate-like ice crystals falling in air.