To investigate the formative process of a spot pattern and the density of a new snow cover on a slope, experimental studies were performed on the accumulation of new snow on artificial wooden plates with various slope angles. The formative process of a spot pattern consists of four stages. In stage 1, a snowflake hits the slope, and then breaks into a few pieces, and each piece slips down while receiving resistance and stops on the slope. In stage 2, a relatively large piece becomes a stopper of other pieces slipping down from an upper part of the slope, and then grows into a large spot. In stage 3, the large spot glows into a taller lump (tall spot) together with snowflakes falling on it. In stage 4, adjacent tall spots join together at the upper part, forming a cavity between the tall spots and the slope. A negative correlation was observed between the spot center interval and snowfall intensity. It was confirmed that the larger the oblique angle of the slope is, the smaller the mean density of a new snow cover on the slope is. The density of lower layers of new snow cover on the slope can be explained by the model with cavities and snow lumps lining alternately.

In 1884, the term “glacier” was translated into Japanese to “Hyoga”, meaning rivers of ice, when the English textbook “Physiography” written by T. H. Huxley in 1877 was translated. This nomenclature was employed by Tei Nishimura, a government official, who studied in Scotland and might be familiar with the flow behavior of valley glaciers. Thus, the term “Hyoga” (a river of ice) was established from an understanding of the glacial flow. Before the term “Hyoga” appeared, features of valley glaciers had already been introduced in Japan in 1877. At this time, “glacier” was translated as “Hyotai” (meaning ice belts), although the description of glaciers as rivers of ice had been written clearly in the original book. The translator of “Hyotai” resisted the translation of glacier to “Hyoga” because hyoga (ice rivers) traditionally meant rivers frozen during the winter; he was also unaware of glacial tongues. After the term “Hyoga” appeared, the term “Hyoden” was often used for “glacier” in Japan during the mid-Meiji era (1884-1895). “Hyoden” means ice fields, and was originally the translation for “glacier” in China. “Hyoga”, which applies to alpine glaciers as well as ice sheets, is in common use in Japan today.

The liquid water content of the snow is essential in wet snow accretion, and temperature and relative humidity significantly influence its properties. In particular, relative humidity is significant at the boundary condition between wet snow and dry snow in nature. In this study, the effect of the relative humidity on the properties of the snow accretion was investigated under the same snow quality and temperature conditions and at higher and lower humidity levels than the boundary value of relative humidity.

Results showed that the density of snow accretion was denser in the low humidity condition under strong wind. The snow accretion angle was larger in high humidity conditions, and the effect of relative humidity was smaller in high wind speeds. Surface hardness was higher in the low humidity condition, and the effect was more pronounced in the high wind speed condition. The impact load was calculated using the surface hardness, and the effect of relative humidity on the snow setting process was clarified. This study demonstrated the effects of relative humidity on snow accretion properties.