The daily discharges of two streams, at Kamabuchi local station, Yamagata prefecture, of Forestry Expreimental Station, were used to study the effect of air temperature upon the thawing of snow ; the following results were obtained.
1. The degree-day factors were calculated by the mean daily maximum and minimum temperatures. The values of the degree-day factors seem to increase with the daily mean temperature. This fact is seen also on laboratory experiments.
2. If the forests were cleared, the values of this factor increased.
3. At the beginning of thawing, this factor is lager as the water equivalent of snow is large.
4. The total amounts of thawing snow of one season measured by the Thaw meter used in our labaratory or calculated from discharge of a small stream were not same to those measured by snow guage, and their relation differs by snow amount of a season ; i. e. the amounts by thaw meter or discharge were greater than those of snow guage when total amount in a season exceeds 800-900 mm. and vice versa.
5. The daily amounts of the thawing snow appear to be less influenced by the solar radiation, because the effect of the greater solar radiation in fine day is cancelled by the freezing temperature in early morning.
6. For the similar daily temperature, the weather of polar air mass seems to bring forth smaller thawing than that of maritime air mass.
