The Relation between the Direction of a Slope and Daily Variation o the Surface Temperature in Winter

Abstract

At Izu Botanical Garden, the southernmost point of Izu Peninsula, Shizuoka Pref., some tropical plants on the slope facing southward are the poorest in their growth. The reason will be because the daily variation of surface temperature is the largest on the bare slope facing southward. The temperature rises up to 30°C even in the middle of winter, but it drops below zero in the early morning of a calm day. On the other hand, at the depth of 5cm below the earth surface, the temperature is always the highest, making the soil very dry. The same conditions were observed at the foot of Tanzawa mountains, Kanagawa Pref. in Jan. 1950.