What is the weather like in the Yangtze River Basin? Why was it formed? (geographical reasons, etc.)

The Yangtze River originates from the Qinghai-Tibet Plateau, and its upper reaches have a plateau mountain climate. The characteristics are: ① As the altitude increases, air, water vapor, dust, etc. decrease, and direct solar radiation increases. The enhancement of ultraviolet radiation is particularly obvious; but the effective radiation also increases. On a snow-covered plateau, the reflectivity increases and the ground absorbs less radiation, so the net radiation is smaller than that of plains at the same latitude; ② The temperature is low, the diurnal range is large, and the annual range is small; ③ Precipitation occurs on the windward side of the humid air flow It increases in the upper part of the plateau and decreases greatly in the interior of the plateau and on the leeward side; ④ The wind is strong.

The middle reaches and lower reaches are located in the monsoon region of eastern my country and have a subtropical monsoon climate.

Cause: Located between the largest continent and the largest ocean, the thermal properties of land and sea are significantly different. In summer, the Eurasian continental low pressure is connected, the subtropical high over the ocean extends westward and northward, and the southeast monsoon emanating from the North Pacific subtropical high brings abundant precipitation; in winter, the northerly wind emanating from the powerful Mongolian high affects the local area. Because the wind shear meets the requirements of monsoon, it is a monsoon climate.

Characteristics: ①High temperature and rainy weather in summer: In summer, the sun’s altitude angle is large, the temperature is high, and the southeast monsoon blowing from the tropical ocean brings abundant precipitation. ② Winters are mild and rainy: the average temperature in the coldest month is above 0 degrees Celsius, and the winters are relatively mild. The reasons are: the local latitude is low, affected by the Kuroshio Current, far away from the source of winter winds, and the undulating terrain weakens the winter winds. 3. The monsoon is significant.

But there is also a special plum rain season in the middle and lower reaches of the Yangtze River. The two sides of the Yangtze River in mid-June are the so-called Jianghuai area. At this time of year, the plum rain season will occur in Jianghuai, and there are many conditions of plum rain, generally divided into normal plum rain, early plum rain, late plum rain, special long plum rain, "short plum rain", "empty plum rain" and inverted yellow plum rain.

Every year from late May to early June, the cold air from the north and the warm air from the south converge in South China, forming the South China quasi-stationary front. Around late June, the force of warm air strengthens, and the quasi-stationary front moves northward to the Jianghuai area, becoming the Jianghuai quasi-stationary front (also known as the Meiyu front). Because the warm air from the south carries a lot of water vapor, when it encounters cooler air masses, a lot of convective activity will occur. Since the forces of warm and cold air were similar during this period, the front stayed in the Jianghuai area. If the cold air is strong, the cloud and rain areas will move southward with the cold air; if the warm air is strong, the cloud and rain areas will move north with the warm air.

In some years, the plum rain starts very early and comes suddenly in late May or early June. Meteorologically speaking, the plum rains that start before the "grain" are usually collectively referred to as "early plum rains". Early plum rains will bring some abnormal phenomena. Since during the period when the plum rain has just begun, cold air from the north to the south is still very frequent in the atmosphere close to the ground. Therefore, after the rain begins, the temperature is still relatively low, and even feels chilly; at the same time, there is no obvious humidity. Phenomenon. Farmers in some areas of the middle and lower reaches of the Yangtze River call the relatively low-temperature Huangmeiyu in this section "cold water Huangmei". In the future, as the rainy season lasts longer and the warm and humid air intensifies, the temperature will gradually rise, the humidity will continue to increase, and the inherent characteristics of plum rain will become more and more obvious. The chance of early plum rains is roughly once every ten years. This early plum rain often presents two situations. One type starts early and ends late, and even ends in late July. The rainy period lasts forty to fifty days, and in some years it lasts for two months. The other is that it starts early and ends early. By late June, the middle and lower reaches of the Yangtze River have entered midsummer. Due to the early arrival of midsummer, droughts of varying degrees in the middle and lower reaches of the Yangtze River are often caused.