Abstract
To investigate the temperature dependency of the angle between the c-axes of neighbour-ing crystals of frozen water droplets, supercooled water droplets of 0.6 to 1.0mm in diameter were nucleated and frozen using single crystal frost ice in temperature ranges of -10 to -15°C, -15 to -20°C and -20 to -25°C. At the range of -15 to -20°C, the peak of the angles between the c-axes of neighbouring crystals was around 20°, on the other hand, there were two peaks around 20° and 70° at the temperature range of -20 to -25°C.The peak around 20°C obtained in the previous paper by authors (1976a) in the temperature range of -17 and -23°C is considered to be affected by relatively warmer temperatures above -20°C. The peak around 70°C appeared at the temperature range of -20 to -25°C in this experiment, strictly coincided with the results of observations in natural snow crystals grown at air temperatures below -20°C. At the temperature range of -10 to -15°C, almost all supercooled water droplets froze single crystals and the orientation of the c-axis of the frozen crystals was the same as that of the seed single crystal frost ice. The directions of protrusions which appeared when the supercooled water droplets were incidently frozen were in parallel to the c-axis of seed crystal. The reason why the orientation of the c-axis of frozen water droplets and the direction of protrusions coincided with the direction of the c-axis of seed crystals were considered. And further, the course of the freezing process of the supercooled water droplets nucleated and frozen by contact with a single crystal frost ice was taken by a motordriven camera mounted on a polarizing microscope.
