It rained so hard in 9 provinces and regions that most of the cities were flooded. Why is there so much rain in China this year?

Heavy rains in 9 provinces and regions flooded the streets in most cities. Why is there so much rain in China this year?

With the arrival of summer, heavy rainstorms have occurred in Guangdong, Fujian, Guangxi, Zhejiang, Hunan, Guizhou, Yunnan, Jiangxi and other provinces in China. In some provinces, heavy rainfall has also caused large economic losses. The personal safety of the majority of residents has also been threatened to a greater or lesser extent. Therefore, everyone must pay more attention to the weather forecast and understand the real-time changes in the weather. So, what is the reason for so much rain this year?

1. Rise in temperature and evaporation of surface water

Sunlight illuminates the water on the surface of the earth, turning the water into water vapor that can evaporate into the air. When water vapor rises and encounters cold air at high altitudes, the two combine to form small water droplets with a diameter of only 0.01 to 0.02 mm. Because these water droplets are small and light, they can be held in the air by the updrafts that exist in the air. As time goes by and the temperature rises, such small water droplets gather more and more, constantly engulfing each other, increasing their volume, and finally falling to form rain.

2. The arrival of the plum rain season in the south

If you are a southerner living in the middle and lower reaches of the Yangtze River, then you must know what the plum rain season is, because there are always so many rainy seasons every year It was rainy for a while. The air humidity in the plum rain season is high, and the clothes dried are prone to mold, so the plum rain is also called "mildew rain". Its formation is mainly due to the convergence of cold air and warm air in South China to form the South China quasi-stationary front. With the arrival of mid-May, the warm air moving from the south to the north will strengthen, and the South China quasi-stationary front will move northward and reach the Jianghuai area, becoming the Jianghuai quasi-stationary front. It is also known as the "Meiyu front".

Since the cold air and warm air are equal during this period, the "Meiyu Front" will stay in the Jianghuai area and generate a large amount of hot and cold air convection activities. Finally, in mid-to-late June, there will be "Meiyu", which is a typical plum rain.

3. The arrival of the pre-flood season in South China

The flood season in South China is divided into two stages: the pre-flood season and the post-flood season. In both stages, there will be rainfall or Heavy rainfall weather. April to June is usually the pre-flood season in South China. The westerly belt on the north side of the subtropical high is the main rainfall zone during this period. It is mostly caused by the collision of cold air and warm air and the outbreak of monsoon, because every year In early April, the summer monsoon from the ocean begins its journey northward.

In the process of going north, the cold air from the north will also move southward, but the cold air does not have enough stamina. Just after crossing the South Ridge, it encounters strong warm air. The two merge. Raindrops are formed, eventually leading to the arrival of the pre-flood season in South China. Because rainfall is caused by the interaction of warm and cold air, frontal rain is the main form during the pre-flood season. The post-flood season generally refers to July to September every year. Rainfall during this period is mainly affected by tropical climates such as typhoons.

These reasons will have an impact on each other. The combined effect has led to the occurrence of heavy rainfall this year. Heavy rainfall will lead to disasters such as floods and landslides. You must pay more attention to the weather forecast and observe your travels. Terrain, ensure your own safety and prevent property damage!