Typhoon is one of the common meteorological disasters in China. Why does it get cold when it comes?

Because with the deepening of summer, the solar radiation energy obtained in the northern hemisphere is still surplus, the SST in the North Pacific Ocean is further rising, and the tropical depression continues to move northward. Affected by the disturbance of tropical depression, a typhoon was produced. Under the influence of geostrophic deflection and subtropical high, the typhoon will move northward along the diverted airflow on the south side of subtropical high, and finally land in the southern coastal area of China, occupying the site originally occupied by subtropical high, dispersing subtropical high and bringing precipitation to this area. The weather feels much cooler because precipitation regulates the temperature.

Typhoon cooling is related to typhoon structure and typhoon maintenance mechanism. Typhoon is maintained because heat energy is converted into kinetic energy. This change, that is, gaseous water becomes liquid water, will release a lot of energy and convert it into kinetic energy. This kinetic energy extracts more high-temperature steam, which releases heat energy, thus forming a heat engine. Therefore, a large amount of liquid water was released and landed in the typhoon, resulting in heavy rain. However, once the typhoon landed, its underlying surface lacked high-temperature water vapor, which cut off the energy and quickly weakened into an extratropical cyclone.

Why does the typhoon come to cool down? Why do many typhoons come from Zhejiang and Fujian provinces in China?

First, typhoons tend to move along the periphery of the subtropical high. They are located in the periphery of the south side of the subtropical high. The typhoon was blocked northward and had to turn around and land in Jiangsu, Zhejiang and Shanghai. Secondly, we should get rid of a long-standing stubborn misunderstanding, that is, the place where the typhoon landed is the area with the strongest wind and rain and the most obvious influence. Generally speaking, a typhoon is a large quasi-circular cyclone, and the area covered by this group (including the landing point and its surroundings) is the area affected by the typhoon.

However, according to the principle of "fairness and rationality", the wind and rain that each area has to bear are not evenly distributed, and the landing sites are not necessarily more severely tested and damaged than other areas. It is normal that the peripheral area of typhoon is more affected than that near the center. In the tropical ocean in summer and autumn, the airflow generally flows from east to west, so typhoons generally move west or northwest. The path of each typhoon is not exactly the same, which depends on the specific situation of atmospheric circulation at that time.

Generally speaking, there are three main paths for typhoons to affect China: the first one is from the eastern Philippines to the northwest, across the South China Sea, and landed on the coast of Guangdong and Vietnam. The typhoon along this route has the greatest impact on Guangdong and Guangxi in China. Second, it will move from the Philippines to the east by northwest, land in Taiwan Province Province, cross the Taiwan Province Strait, land again in Fujian Province and Zhejiang Province, or move to the northwest and land along the coast of Taiwan Province Province. Zhejiang and Jiangsu provinces.

The typhoon on this path has the greatest impact on the whole East China. The third is to move from the eastern Philippines to the northwest, and then turn northeast to Japan. The typhoon on this path has relatively little impact on China.