Why does it keep raining in the south this year?

Because it is the plum rain season now, the following is some information about the plum rain: 1. The plum rain season in the middle and lower reaches of the Yangtze River in my country is usually around mid-June to early July every year. The sky has been gloomy for days, and the precipitation has been continuous, sometimes heavy and sometimes light. Therefore, there is a popular proverb in southern my country: "The rain hits the yellow plum heads, and there is no sun for forty-five days." Continuous rain, high temperature and high humidity are the main characteristics of Meiyu. Quite different from the climate in areas at the same latitude, Meiyu refers to the weather and climate phenomena that occur in a certain area and in a certain season. Research has found that the Eurasian continent is between 20N and 40N, a zone alternately controlled by subtropical high pressure and westerly belts. On the west coast of the continent, in summer, controlled by the downdraft from the east side of the subtropical south pressure, the weather is sunny and cloudy, and the climate is hot and dry; in winter, under the influence of the westerly belt, warm and humid air is brought from the Atlantic Ocean, resulting in more precipitation, making the climate milder. Rainy. That is, it exhibits a subtropical Mediterranean climate with dry summers and wet winters. On the east coast of the continent, controlled by the west side of the subtropical high in summer, the sinking air is originally drier, but absorbs a large amount of water vapor from the warm and humid sea surface, thus bringing abundant precipitation and creating a humid subtropical climate. Due to the strong contrast between sea and land, a unique monsoon climate is formed here. Its notable feature is summer rain and winter dryness, with rainfall concentrated in summer, which is exactly the opposite of the Mediterranean climate. If compared with the east coast of the UK at the same latitude, it is completely different. There will be no long-term rainy weather before and after the summer monsoon in the mid-latitudes of the east coast of the United States. People will never feel the long-term muggy weather, and mold is unlikely to occur. It can be seen that the precipitation seasons are very different at the same latitude. Therefore, in the world, yellow plum appears only on both sides of the middle and lower reaches of the Yangtze River in my country, roughly starting from the east of Yichang and in the area between 29 and 33 degrees north latitude, as well as in southeastern Japan and the southernmost part of the Korean Peninsula. In other words, Meiyu is a unique weather and climate phenomenon in East Asia, and in my country it is a unique weather and climate phenomenon in the middle and lower reaches of the Yangtze River. 2. Rainbands Although Meiyu is a unique weather and climate in the middle and lower reaches of the Yangtze River, its occurrence is not isolated. It is closely connected with the north-south displacement of large-scale rainbands. In the eastern region of my country east of 110E, during the flood season from mid-May to early June, the main rainbands swing over the Nanling Mountains and the area south of Nanling. In individual years, although it moves to the north of Nanling in a certain period of time, judging from the multi-year average situation of a pentad (a pentad of five days) or a ten-day period, it tends to remain south of 28N and 29N. This period is called the "Jiangnan Rainy Season" or the "South China Pre-Flood Season". In mid-to-late June, the main rain belt moved northward to the range of 29N-33N (i.e., from Yichang, my country in the west, to the Yangtze River Estuary in the east, and then across the sea to Japan; from the Lianghu Basin in my country in the south to the south bank of the Huaihe River in the north), with stability and little movement. At this time, the area south of Nanling was outside the rain belt, and the rainy weather ended; while the middle and lower reaches of the Yangtze River bid farewell to the sunny early summer and ushered in the rainy season, with heavy rains and heavy rains appearing from time to time, which lasted until In early July, this is the famous plum rain season in the middle and lower reaches of the Yangtze River. Starting in mid-July, the rain belt moved northward again, reaching the area north of 33N. It has stagnated and lingered in the Yellow River, Huaihe River Basin, North China, Northeast China and other places, causing heavy rainfall again and again, which are called "Yellow-Huaihe Rainy Season" and "North China Rainy Season" respectively. At this time, the plum rain in the middle and lower reaches of the Yangtze River ends, and the scorching sun hangs high. Entering the hot summer season. This kind of weather lasted until late August, and then the rain belt quickly retreated southward as the cold air gradually became active. In less than a month, the rain belt retreated all the way to the coastal areas of South China. This regular change of rain belts shows that the Meiyu in the middle and lower reaches of the Yangtze River is not an isolated and local weather and climate phenomenon, but an integral part of the main rainy season activities in eastern my country. It is the main rain belt moving northward along the Yangtze River. A reflection of the stagnation in the middle and lower reaches.