On Snow Crystals of Bullet Type

Abstract

The basic properties of snow crystals of the single bullet type and a combination of bullets were studied. The length of c-axis, the axial ratio and number of bullets which form a combination of bullets, using approximately one thousand and four hundred snow crystals of bullet type observed in the Ishikari Plain in Hokkaido were studied. The results were as follows ; the mean length of c-axis of the single bullets 0.59mm, the standard deviation 0.16, the skewness 0.05 and the kurtosis 1.67, and the mean axial ratio (c/a) of the single bullets is 3.2. Each value of two, three and four-combined bullets were nearly the same as the single bullets.
It was assumed that the single bullets were produced by the disintegration of the combination of the bullets during their descent. In relation to the origin of the combination of bullets, it was surmised that the combination of bullets grew from either dust particles with many corners which were introduced by Stiive, of from frozen droplets with many spicules which produced when supercooled droplets froze suddenly.