@article{oai:niigata-u.repo.nii.ac.jp:00028130,
 author = {Izumi, Kaoru},
 journal = {新潟大学積雪地域災害研究センター研究年報, 新潟大学積雪地域災害研究センター研究年報},
 month = {Dec},
 note = {As wet snow plays one of the most important roles in the release of avalanches in temperate snowy districts, observations and experiments were made on the characteristics of hardness of wet snow in the field and laboratory. By measuring Kinosita's hardness of natural wet snow over a wide range of snow density, a relation among hardness, dry density and free water content of wet snow was obtained for each snow type. As hardness of snow decreased with an increase in water content according to this relation, the lower limit of hardness of snow due to water content was obtained by immersing natural snow in 0℃ water. Unsaturated wet snow at the surface of a natural snow cover, having less hardness than the limit, was considered to have reduced its hardness due to solar radiation. Laboratory and field experiments on hardness of snow showed that free water contained in snow decreased its hardness, and solar radiation further decreased its hardness down to a value below the limit caused only by water content. A relation between the amount of solar radiation absorbed by snow and decrease of snow hardness was quantitatively obtained. The mechanism of decrease in snow hardness caused by free water in snow and solar radiation were explained based on thin section analyses of snow. From the obtained results, it was revealed that the weak wet snow layer of the sliding plane of some surface avalanches which occurred in Niigata Prefecture was formed by solar radiation.},
 pages = {1--42},
 title = {STUDIES ON THE HARDNESS OF WET SNOW AND ITS DECREASE DUE TO SOLAR RADIATION},
 volume = {9},
 year = {1987}
}