Senior high school: the influence of the advance and retreat of summer monsoon on the climate in China

Summer monsoon The southeast monsoon from the Pacific Ocean and the southwest monsoon from the Indian Ocean are collectively called summer monsoon. It comes from the ocean, warm and humid, and its nature is completely opposite to the winter wind.

The activity mode of summer monsoon is also different from that of winter monsoon. In winter, the wind is strong and grows fast, and it often goes south quickly in an explosive way. The summer monsoon is very weak and grows slowly. It reached the southern coast of China in April and May, and every time it moved forward, it had to stop before it could move on. It arrived in the Yangtze River valley in June, entered Yunnan and Tibet, and was extended to North China and Northeast China in July and August. In September, forced by the winter wind, it quickly withdrew to the south of the Yangtze River. 10, the winter monsoon is further strengthened, and the summer monsoon stops landing on the mainland. The summer monsoon affects China for about 5 months in the Pearl River basin, 4 months in the Yangtze River basin, Yunnan and Tibet, and only 2 months in North China and Northeast China.

The summer monsoon is very strong, and you can cross the mountains and enter the southern plateau.

Front and rain belt, so as to form precipitation (rain, snow, hail, etc.) in an area. Fall to the ground, collectively referred to as precipitation), water vapor must be supplied.

When the summer monsoon comes, it brings a lot of water vapor from the ocean, and the precipitation in China increases significantly. The hot and humid summer monsoon only provides the possibility of precipitation, and the water vapor in the air condenses into raindrops before it falls to the ground. There must be some force that makes the hot and humid air cool in the process of rising, and the water vapor inside can condense and fall in large quantities.

The air is heated strongly and rises sharply, which can form precipitation. This is how summer thunderstorms are formed. The precipitation caused by this method is called convective rain. Although the convective rain is fierce, the scope is not large and the rainfall time is not long. Generally speaking, there is not much rainfall.

Humid air is influenced by topography, and rising along the hillside can also form precipitation. The precipitation thus formed is called topographic precipitation. The topographic precipitation in many mountainous areas of our country is very obvious, especially on the hillside facing humid air, which is much richer than that in the neighboring lowlands.

The more common precipitation method is frontal rain. When two different kinds of airflow meet, there will be an obvious interface, called front. On the front, warm, humid and light air rises above dry, cold and heavy air, and water vapor cools and condenses in the rising process, resulting in precipitation.

Between winter and summer monsoon, there is a broad front area, and rain belts with more precipitation often appear in this area.

When the monsoon advances and retreats, there will be rainy weather where the rain belt is located in the rainy season, and it will enter the rainy season. The rain belt moves with the advance and retreat of the summer monsoon, so the rainy season in the south of China starts early and ends early, while the rainy season in the north starts early and ends early.

Rain belt movement is most obvious in eastern China. In May, the rain belt lingered around Nanling and became the rainy center of the country. At the beginning of June, after the rain belt pushed into the Yangtze River basin, it stayed between the Yangtze River and Huaihe River for about a month, and it rained continuously. This is the rainy season in the middle and lower reaches of the Yangtze River. It was not until early July that the rain belt continued to move west and north. Therefore, the northern part of China is generally dry from spring to early summer, and the rain can't meet the needs of agricultural production at that time. After the meiyu in the middle and lower reaches of the Yangtze River ended, there were not many opportunities for the front. The water demand of a large area of farmland cannot be met by convective rain and topographic precipitation alone. In this way, there is a possibility of midsummer drought in the Yangtze River basin, forming a summer drought.