抄録
In this paper there were researched the heavy snows in Japan which happened in the term of-Nov. 19541Mar.1959. There were two sources of heavy snow. One of them had a common origin, with ordinary rainfall by cyclone but the temperature was low, and the snow amounts increased according as the temperature rose till it reached to the limit between rain and snow.
The other was the convection which happened when the temperature of upper air fell in excess and the layers in the atmosphere became unstable. The air temperature apposite to heavy snow by the convection was about 35°C at 500mb, about 20°C at 700mb, and about 10°C at 850mb. These temperatures were lower than one at the limit between rain and snow, and the snow amounts decreased in proportion as air-temperature rose or fell from these points. By the former heavy snow happened on inland of the Pacific side. The latter was the cause of the heavy snow over the districts, along Japan Sea and had much more frequency.
Heavy snow by the convection happened when NW monsoon was severe and were the greatest deal in Hokuriku District. When upper air-temperature were lower, heavy snow happened nearer to the coast of Japan Sea and fell over more inland according as temperature rose.
