Abstract
In order to study the microclimate of small concave ground in different size, subjected to the seasonal variation of the temperature, the authors placed maximum and miumum thermometers provided with small screen shelters at 10cm above each of artificial neary cincular ground and the flat bare ground as the standard plot (see Fig. 1). And observation are made from April 1953 to February 1954. The maximum air temperature in all concave grounds always show unexpectedly much warmer than in the flat ground, if the weather condition is fine, and it become much warmer with the decresing diameter, so far as the diameter ranges between 5 to 1 meter.
On the other hand the nocturnal air temperature in the concave ground is much colder than on the standard plot, especially it becomes very cold in winter, being acumlated cold air at the bottom of the concave ground.
It is seen from Fig. 2, that the nocturnal air temperature in the concave grounds becomes much colder with increasing diameter.
