Why is it rainy in autumn?

Because autumn comes after summer, and the temperature is high and the air humidity is high in summer, the cold air will continue to go south in autumn. Whenever cold air comes, it will meet with high temperature and high humidity air, and the originally warm air will rise to high altitude, and water vapor will condense to form frontal rain. So in autumn, as long as the cold air comes, there will be precipitation, which is the reason for an autumn rain and a cold. In autumn, the cold air is weak and it is easy to form a rainy weather with a long duration. The weather gradually changed from summer to winter in a series of autumn rains, and the temperature and humidity gradually decreased. Autumn begins with autumn rain and ends with autumn rain. The first autumn rain every year marks the end of hot summer, and the arrival of autumn often occurs in September of the solar calendar. Every autumn rain is a step farther from summer and a step closer to winter. Finally, it is often accompanied by a strong cold air and an autumn rain, and then the temperature drops sharply, the weather clears up and the humidity drops sharply, which marks the official arrival of winter. This process often occurs from the end of October to the beginning of February in the solar calendar. In winter, under the influence of the strong wind in winter, the air humidity becomes very low, so the precipitation in winter is very low, and it often rains only. In spring, with the direct point of the sun moving northward, the solar radiation is gradually strengthened, the temperature is constantly rising, and the marine monsoon activity is constantly strengthened, which leads to rainy weather in southern China, while the northern region will continue to be dry and rainy in winter, gradually warming up in continuous sunny days, and gradually transitioning to summer. After entering the summer, under the influence of the summer monsoon from the ocean, the north will also become wet.