The reasons for the difference in precipitation between winter and summer in Penghu Islands

The precipitation in Hainan Island is concentrated from May to October. There is less precipitation from November to April of the following year, which is the dry season. As shown in the figure, take Haikou as an example. Hainan Island, where Haikou is located, has a typical tropical monsoon climate, with high temperatures throughout the year, with an average annual temperature of 20°C, large annual precipitation, and distinct dry and rainy seasons. There is less precipitation in the southwest of Hainan Island.

The main reason for the seasonal differences in precipitation in Hainan Island is the influence of the monsoon. In summer in the northern hemisphere, the pressure and wind belts move northward, and the southeast trade winds in the southern hemisphere move northward, cross the equator, and are deflected by the geostrophic deflection force to form the southwest monsoon. The arrival of the southwest monsoon brings abundant precipitation. Of course, typhoons landing during this season will also bring precipitation. In winter in the northern hemisphere, the air pressure and wind belts move southward, and Hainan Island is controlled by the northeast monsoon. The northeast monsoon blows from the mainland, causing less water vapor and less precipitation, forming a dry season.