What does the rainy season mean?

What does the rainy season mean? Meiyu mainly occurs in the subtropical monsoon climate zone, generally including the middle and lower reaches of the Yangtze River and Taiwan Province Province in China. At the turn of spring and summer, it is the time when the south enters the rainy season. On rainy days for several days, the air is full of moisture, which is disturbing. Let's take you to know more about what the rainy season means.

What does the rainy season mean? Meiyu season 1 is a climate phenomenon that the warm and humid air flow in the Pacific Ocean brought by the southeast monsoon passes through the middle and lower reaches of the Yangtze River in China, Taiwan Province Province in China, south-central Japan and South Korea every June and July. Because it is now the mature period of plums in Jiangnan, it is called Meiyu season. Note: At present, the academic circles believe that the East Asian summer monsoon started from the South China Sea summer monsoon (in late May on average) and belongs to the category of tropical southwest monsoon. The South China Sea summer monsoon gradually strengthens and moves northward, and moves northward to the middle and lower reaches of the Yangtze River during the meiyu period, and merges with the subtropical southwest monsoon on the northwest side of the subtropical high to form the meiyu belt.

In the rainy season, the air humidity is high and the temperature is high, so clothes are easy to get moldy, so some people call the rainy season "moldy rain". After the rainy season, the weather began to be dominated by the Pacific subtropical high and officially entered the hot summer.

Meiyu mainly occurs in the middle and lower reaches of the Yangtze River in China, Taiwan Province Province in China, Liaodong Peninsula, the southernmost tip of the Korean Peninsula and the subtropical monsoon climate zone in south-central Japan. There is no plum rain in other parts of the world at the same latitude. There is no obvious plum rain in South China.

Every year from late April to early May, cold air from the north and warm air from the south meet in South China, forming a quasi-static front in South China. By the end of May, the influence of warm air was strengthened, and the quasi-static front moved northward to Jianghuai area, becoming the quasi-static front of Jianghuai (also known as Meiyu front). Because the warm air from the south carries a lot of water vapor, when it meets the cold air mass, it will produce a lot of convection activities. Because of the equal influence of cold and warm air during this period, the front stays in Jianghuai area.

Typical plum rains generally "enter plum blossoms" in the middle and late June, and bloom in early to mid-July. Meiyu refers to the rainy days before plum blossom, which generally starts in mid-April and lasts for about half a month.

What does the rainy season mean? In the middle and lower reaches of the Yangtze River in China, it is usually from mid-June to early July every year. In the past few days, the sky has been gloomy and the precipitation has been constant, sometimes big and sometimes small. Therefore, there is a popular proverb in southern China: "Rain hits Huangmei's head and there is no sun for forty-five days." Continuous rain, high temperature and high humidity are the main characteristics of plum rain.

Very different from the climate in the same latitude area, Meiyu refers to the weather and climate phenomenon that occurs in a certain area and a certain season. It is found that Eurasia is between 20 N and 40 N, which is alternately controlled by subtropical high and westerly belt. The west coast of the mainland is controlled by the downdraft on the east side of the subtropical south pressure in summer, with sunny weather, partly cloudy and dry climate; In winter, under the influence of westerlies, warm and humid air is brought from the Atlantic Ocean, resulting in more precipitation and a mild and rainy climate. That is, the subtropical Mediterranean climate is dry in summer and humid in winter.

The east coast of the mainland is controlled by the west side of subtropical high in summer, and the downward flow is dry, but it absorbs a lot of water vapor from the warm and humid sea surface, bringing abundant precipitation and producing a subtropical humid climate. Due to the strong contrast between land and sea, a unique monsoon climate has formed here, which is characterized by rainy summer and dry winter, with rainfall concentrated in summer, which is just the opposite of the Mediterranean climate.

If compared with the east coast of the United States at the same latitude, it is also a world of difference. There will be no rainy weather for a long time before and after the summer monsoon in the mid-latitude zone of the east coast of the United States, and people do not feel the feeling of sultry weather for a long time, so it is difficult to appear moldy. It can be seen that the precipitation season at the same latitude varies greatly. So there are only Huangmei in the middle and lower reaches of the Yangtze River in China, starting from the area east of Yichang and 29-33 degrees north latitude, as well as the southeast of Japan and the southernmost tip of the Korean Peninsula. In other words, Meiyu is a unique weather and climate phenomenon in East Asia, but it is a unique weather and climate phenomenon in the middle and lower reaches of the Yangtze River in China, which generally occurs in late spring and early summer.

Although Meiyu is a unique weather and climate in the middle and lower reaches of the Yangtze River, its appearance is not isolated, but closely related to the north-south displacement of a large-scale rain belt.

In the east of China, east of 1 10E, the main rain belt swings in Nanling Mountains and its south area from mid-April to early May in flood season. In recent years, although it moved to the north of Nanling within a certain period of time, it often stayed in the south of 28N and 29° n from a waiting period (5 days) or the multi-year average of 10 days. This period is called "rainy season in the south of the Yangtze River" or "pre-flood season in South China".

In the middle and late May, the main rain belt moves northward within the range of 29° n-33° n (that is, it starts from Yichang in the west, reaches the Yangtze River estuary in the east, and then crosses the sea to Japan; From the two lakes plain in the south to the south bank of Huaihe River in the north, it is stable and less moving. At this time, the area south of Nanling is outside the rain belt, and the rainy weather is over; The middle and lower reaches of the Yangtze River bid farewell to the sunny early summer and ushered in the rainy season. Heavy rain and rainstorm appeared from time to time and lasted until the beginning of July. This is a famous rainy season in the middle and lower reaches of the Yangtze River.

From mid-June, the rain belt moved northward again, reaching the area north of 33 N. Stagnation and wandering in the Yellow River, Huaihe River Basin, North China, Northeast China and other places have caused heavy rainfall again and again, which are called "Huanghuai rainy season" and "North China rainy season" respectively. At this time, the plum rains in the middle and lower reaches of the Yangtze River ended, the sun hung high and entered the hot summer season. This kind of weather will last until the end of August, and then the rain belt will quickly withdraw southward with the gradual activity of cold air. In less than a month, the rain belt will always retreat to the coastal areas of South China. The regular change of this rain belt shows that the plum rain 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 China, which reflects the stagnation of the main rain belt in the middle and lower reaches of the Yangtze River.