Explanation of Meiyu phenomenon with meteorological phenology knowledge

Meiyu (Huangmeitian) refers to the cloudy and rainy natural climate phenomenon in the middle and lower reaches of the Yangtze River, Taiwan Province Province, south-central Japan and south Korea every year from late June to early July. Because plum rains occurred in the mature period of plums in the south of the Yangtze River, people in China call this climate phenomenon "plum rains", and this period is also called "plum rains season". 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 in Central China, South China, Taiwan Province Province and other places began to be dominated by the Pacific subtropical high, and officially entered the summer heat.

In early summer, there are often long rainy days in the Jianghuai basin. At this time, the utensils are easy to be moldy, so it is also called "moldy rain" or "mildew" for short; It is also called "Plum Rain" or "Huang Meiyu" because plums in the south of the Yangtze River are yellow and ripe. It is recorded in China's historical records. For example, The Book of Beginners quoted the compilation of Emperor Liang Yuan in the Southern Dynasties, "Plum blossoms have plum rains when they are ripe". Liu Zongyuan's Plum Rain in the Tang Dynasty: "Shi Mei welcomes the rain, and it is worth the late spring." Wait a minute. In China's almanac, it was recorded that there was a mildew rain all day long: the first day was called "entering the mold" and plum rain.

The end date is called "mildew". The first day after the awn is planted, it is moldy, but it is not moldy on the first day after the hot summer. Mold always enters from June 6th to 15, and mold always leaves from July 8th to 19. There is an obvious rainy season in the eastern part of China, with a long rainy period and relatively concentrated rainfall, which is caused by the north-south displacement of the main rain belt in the east-west direction and is the transformation of East Asian atmospheric circulation to Meiyu at the turn of spring and summer.

The unique phenomenon during the period. After mid-June, the rain belt remained in the Jianghuai basin, which is Meiyu. "(However, because the current language is a habitual language, the plum rain mentioned now is not limited to the Jianghuai valley to Japan, and the continuous precipitation in the eastern part of China, such as Fujian, during the plum rain season is also called plum rain. ) The stay time of rain belt is called "Meiyu season", the day when Meiyu season begins is called "entering plum blossom", and the day when it ends is called "emerging plum blossom". In addition, due to the high humidity in the air during this period, everything is easy to be damp and moldy, so people gave Meiyu an individual name, called "Moldy Rain". Five Miscellaneous Torches by Xie Zaihang in Ming Dynasty. "Tianbu No.1" describes: "Every year in March and April in the south of the Yangtze River, the bitter rain continues, and everything is moldy and rotten, commonly known as plum rain, and plums are covered when they are green and yellow. From Xu Huai to the north, it is often dry in spring and summer. By the turn of June and July, it was raining heavily and everything was moldy. "Li Shizhen, an outstanding medical scientist in Ming Dynasty, clearly pointed out in Compendium of Materia Medica:" Plum rain or mildew rain, when it comes to clothes and things, will produce black mold. ".