Why has it been raining recently in 22?

Since this summer, how often has there been continuous rainfall in China, and even floods have occurred in various places, and many people will wonder why this has happened? So why is there so much rain this year? Why is there so much rain in 22? Next, let's take a look at this issue of the old yellow calendar!

Why is there so much rain this year? Why is there so much rain in 22?

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Why is there so much rain this year?

According to the introduction, rainfall in China can be divided into four types: frontal rain, convective rain, orographic precipitation and typhoon rain. However, all types of rainfall need three conditions: sufficient water vapor, suitable dynamic lifting conditions and a large number of condensation nuclei in the air.

the most important reason why the rainfall in flood season is so violent, lasting for a long time and having enough stamina is the good water vapor condition. For example, the recent plum rains in Jiangnan and Jianghuai areas are the continuous rainfall (frontal rain) brought by sufficient water vapor.

There are two typical "water vapor channels" that lead to violent and persistent heavy precipitation in China during flood season, and the Pacific Ocean and the Indian Ocean are powerful "suppliers".

Why is there so much rain this year? Why is there so much rain in 22?

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China is a country with monsoon climate, and winter is mainly controlled by the north wind, such as Siberian cold air, which frequently "cools" our country under the encouragement of the north wind; In summer, the wind direction changes greatly, from north wind to south wind, which transports the water vapor from the ocean to the land. Therefore, with the "east wind" of the summer monsoon, the Pacific Ocean and the Indian Ocean can continuously transport the important "raw material" needed for precipitation to China's land-water vapor.

Specifically, one of the important water vapor channels that affect China in flood season is the tropical marine air mass from the Pacific Ocean, which, with the South China Sea monsoon and the southeast monsoon, enters South China along the subtropical high system, and even affects North China and Huanghuai with the movement of the subtropical high; The other is the equatorial air mass in the Indian Ocean, which is "blown" by the southwest monsoon and enters the southwest, northwest and middle and lower reaches of the Yangtze River.

Compared with the water vapor in the Pacific Ocean, the water vapor and convection activities in the Indian Ocean brought by the southwest monsoon are more unstable, and the places affected by it "splash water" for a longer time and more violently. For example, recently, affected by the warm and humid air current in the southwest, Jingmen, Yichang, Enshi, Hubei and Pengshui, Chongqing were hit by 25 mm torrential rain within 24 hours, and the rainfall in some places reached 346 mm.

"In summer, in addition to these two typical water vapor transport channels, water vapor from the Atlantic Ocean, the Arctic Ocean and the Sea of Japan will also affect China, and heavy rainfall may also occur in Xinjiang and Northeast China, and the disaster-causing nature cannot be ignored," Hu Xiao added.

in addition, as the "pushing hand" behind the flood season weather in China, the intensity and location of subtropical high determines the distribution changes of rain belts in the central and eastern regions of China. Dragon Boat Water in South China, Plum Rainy Season in South China and Seven Downs and Eight Ups in North China always transport the prepared water vapor to specific places in a general time range every year, as if it rains at a fixed point with its own navigation.

Why is there so much rain this year? Why is there so much rain in 22?

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Related reading: Introduction to the meaning of flood season

Rivers and lakes floods are obviously concentrated in a year, which is prone to flood disasters. Because of the different geographical location and flood season, the length and time sequence of flood season are also different.

The river regularly rises significantly during the year. Rainfall or melting snow in the basin can cause the river to rise significantly. In spring, when the climate gets warmer, seasonal snow melts, river ice thaws or spring rains in the basin, causing the river to rise, which is called spring flood. Because peach blossoms are in full bloom, it is also called peach blossom season (or peach blossom season). In northern China, the phenomenon of rising water caused by thawing river ice in spring is called ice flood. The Yellow River has ice flood in Ningxia-Inner Mongolia section, Shandong estuary section and the lower reaches of Songhua River, which flows from south to north. In summer, the heavy rain in the basin or the melting of alpine glaciers and snow make the river rise sharply, which is called summer flood. In China, it is customary to call the flood water that occurs before and after the dog days in summer as the flood season. In autumn, due to heavy rain, the river rises sharply, which is called autumn flood.

The time, frequency and their combination of rivers in different areas of China are different in flood season.