Abstract
The author observed the diurnal change of the local air temperature distribution by the 4 portable-thermographs which were set at the rigde of the low spur slope of the mountain. (Fig. 1.) Some results, on the March 4, 1951, is shown in Fig. 2. As is well known, the lower station has the greater range than the higher, and the difference of the range of 4°C per 100m. The air temperature of the highest station ascends earlier than the lower station after the sunrise and descends more slowly before the sunset. This figure, however, can not show the change in detail, because the air temperature generally has the small fluctuations.
(1) So he estimated the differences of the small fluctuations in short time (6 minutes) within the observed small area within 95% reliability. (Fig. 3.) We can conclude that the fluctuations reach about 0.3°C before the sunrise, 0.4-0.5°C in the daytime, and about 0.2°C after the sunset. And the stronger the winds, smaller the fluctuations become.
(2) The nocturnal downslope winds have a cycle of 1.5-2.0hours, flowing with the speed of 3-4m/s and drop the air temperature usually 0.3-0.4°C in 30-40minutes or occationally about 2°C in 2hours.
(3) The changes of the lapse rate or the inversion rate of the air temperature in 24hours are shown in Fig. 4. Temperature decreases with elevation from about 1hour before the sunset, and the maximum of their rates reaches about 3°C/100m. The maximum inversion rate is about 2°C/100m before the sunrise.
