Item: Experiments of depth hoar formation under extremely low temperature
Title: Experiments of depth hoar formation under extremely low temperature
Proceedings: Proceedings of the 1998 International Snow Science Workshop, Sunriver, Oregon
Authors: Y.Kamata and A.Sato
Abstract: To investigate the growth of depth hoar crystals in a very cold region, an experiment was carried out for three days with temperature gradients of 200 Kim. After three days of fixed conditions, snow samples were divided into three layers. Photographs of the snow grains were taken using a microscope for each layer. The mean cross-sectional area of the digitized grains was determined as a diameter of a circle with an equivalent area. Snow crystals of these layers were also classified into three types. Growth direction of depth hoar crystal was also observed by vertical thin section for each layer. From these experiments, the texture of original fine snow was considerably changed into sharply edged hoar grains. They were solid and skeleton types due to dry metamorphism. And the crystals grew toward warmer part. Depth hoar crystals developed where temperature was high and temperature gradient was low more than where temperature was low and the gradient was high. This indicates that the growth of depth hoar crystals is controlled by temperature itself rather than temperature gradient under extremely low temperature.
Keywords: depth hoar, extremely low temperature, saturated water vapor concentration
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