What is the relationship between wind direction and weather change?

Wind direction is closely related to weather changes. In the winter half year, the vast area of our country is controlled by Mongolian cold high pressure, and the wind direction is northerly (northwest or northeast wind), which brings dry and cold air to Siberia and Mongolian plateau, so the weather is sunny and there is less rain and snow. During the dormant period, the south of China was controlled by subtropical high. Although the southeast wind blows from the sea, due to the prevailing downward flow under high pressure, the water vapor in the near-surface layer is difficult to rise to form clouds and rain, so it is a sultry summer dry weather, and the temperature is often as high as 35 ~ 40℃. Only in the afternoon, there are short-term showers in some areas due to thermal convection.

From March to April, warm and humid air carried by southerly winds blowing from the sea meets cold air (northerly winds) that still has some influence in South China, forming the rainy season in the first flood season in South China. In the middle and late June, the ridge line of subtropical high jumped northward to about 20 north latitude, and the cold air (northerly wind) in the north met the southerly wind in the northwest of subtropical high in the Yangtze River basin, forming the Meiyu period in the middle and lower reaches of the Yangtze River. After mid-July, the ridge line of subtropical high jumped further north to about 30 north latitude, and the north and south air met in the Yellow River and Huaihe River basins to North China, and the rain belt moved to this area, forming the rainy season in the north. After the end of July, southerly winds reach the north of North China to the northeast, and then form the rainy season in the north and northeast of North China.