What month is the rainy day?

Meiyu refers to the rainy weather that lasts from the beginning of June to the middle of July every year in the Gregorian calendar. At this time, due to long-term rainy and sunny and humid weather, household utensils are prone to mildew, which is also called mildew rain by the people. Meiyu weather mainly occurs in Jiangnan, the middle and lower reaches of the Yangtze River, Jianghuai, South Korea, Japan and other places.

Meiyu season is called Meiyu because it is when plums are ripe in the south of the Yangtze River. Influenced by China's traditional culture, South Korea calls it "Long Horse", which is vividly characterized as "Long Hair". Japan calls it "Biau", which comes down in one continuous line with "mildew rain".

Meiyu is a unique product of East Asian summer monsoon advancing northward in stages, and it is a unique weather and climate phenomenon in East Asia. Meiyu season is also the most significant season of monsoon precipitation in China. The climatic characteristics of Meiyu season are concentrated precipitation, heavy rainfall, few sunshine hours, cloudy and windy.

Formation condition

1. There is blocking high pressure or stable high pressure ridge in the middle troposphere in high latitudes of Asia, and the atmospheric circulation is relatively stable with little change.

2. The westerly circulation in the mid-latitude area is gentle, and frequent short-wave activities provide cold air conditions for the Jianghuai area.

3. The western Pacific subtropical high has an obvious process of extending westward and jumping northward. The ridge line of the 500 HPA subtropical high is stable between 20 and 25 degrees north latitude, and the warm and humid air flow is transported from the edge of the subtropical high to the Jianghuai basin. Under this circulation condition, Meiyu front lingers in the Jianghuai basin, often accompanied by southwest vortex and shear line, and the mesoscale system on Meiyu front is active. It not only maintains the continuous precipitation during the Meiyu period, but also provides abundant water for the rainstorm.

Reference to the above content: Baidu Encyclopedia-Meiyu