Morphology of Ice Crystals Grown from the Vapour at Temperatures between -4 and -1.5°C

Abstract

Ice crystals grown in a supercooled cloud at temperatures from -4 to-1.5°C in a cloud chamber of the type of unforced air flow have been studied, with the following findings: All of them are plates in shape, which are categorized into a sector plate (-4.0∼-2.5°C), a fern-shaped plate (-3.0∼2.0°C) and a plate with a scalloped periphery (-2.0∼1.5°C), and the rate of growth in the a-axis direction increases as the temperature approaches the melting point. The three types of crystals have a multilayered and plate construction in common. The most conspicuous in the layered construction is the plate with a scalloped periphery, which is characterized by the direction of growth of the tip of a branch that is not always parallel to an a-axis, the number of such branch being vast.