Abstract
Analyzing the aerological data at Syowa Station and the surface data at Syowa and Mizuho Stations Antarctica in 1979, we discuss the mechanism of cloud formation during high-pressure conditions. It was frequently (over 30%) overcast during high-pressure conditions at Syowa Station except in December, and a similar tendency can be found at Mizuho Station. Moreover, snowfalls were observed at Syowa Station even in these conditions and the frequency of such days was rather larger in winter than in summer. In many cases of high-pressure, a stable layer or an inversion layer was found; some stable layers were around 800mb level and others were near the ground surface. It was considered that the formation and development of clouds was connected directly with the stable layers. The main mechanisms for forming clouds would be the weak convection in the layer below stable layer or inversion layer, the mixing of cold air with moist air because of wind shear and surface radiative cooling, and for developing clouds would be radiative cooling at the cloud top.
