Unusual Types of Single Ice Crystals Originating from Frozen Cloud Droplets

Abstract

Laboratory experiments were conducted to study the formation process of unusual types of ice crystals, using a cold chamber in the temperature range ?15 to ?25°C. Ice crystals of the bottle type seem to originate from frozen water droplets with spicules. Ice crystals of twin columns (or twin bullets) with plates were found. By observing the various stages of development of pyramidal faces of ice crystals with plates and ice crystals of ?single bullet? type?it was concluded that these pyramidal portions of ice crystals may originate from the spicule of frozen droplets or from hemispherical frozen droplets, and that the pyramidal faces can survive further growth at temperatures colder that ?25°C.