Why is it rainy in winter in Sichuan Basin and sunny in West Sichuan Plateau?

The cold air from the north has little effect on the winter in Sichuan Basin, and the warm and humid air from the south has little effect. Therefore, the reasons for the rainy and rainy winter in Sichuan Basin are the low altitude in the basin, the evaporation of water (paddy fields in winter), high air humidity and cloudy weather. Because of the high temperature in the lower layer and the low temperature in the upper layer at night, it is easy to form precipitation (late rain), so it rains continuously in Sichuan Basin.

The western Sichuan Plateau is located on the east side of the Qinghai-Tibet Plateau. Winter is mainly affected by cold and high pressure, with sunny weather and abundant sunshine. If there is a strong warm and humid air flow, precipitation (snowfall) can be formed. Otherwise, it is mainly sunny.