High temperature in the south and heavy rain in the north, why is the weather in China so extreme this year?

Every summer, the main factor affecting the weather in China is the western Pacific subtropical high.

In summer, the direct point of the sun will move northward, and so will the western Pacific subtropical high. On the northwest edge of the western Pacific subtropical high, a rain belt will be formed in China, because the warm and humid airflow from the ocean will move along the ridge of high pressure and form frontal rain when it meets the cold air. With the movement of the western Pacific subtropical high, the rain belt in China will also move, resulting in rainfall in South China, plum rain in North China and rainy season.

Under the rule of the western Pacific subtropical high, it will be cloudy and sunny, and the local temperature will be higher. Recently, high temperature weather occurred in many places in southern China, mainly because of the enhancement of subtropical high, which made many places in southern China ruled by subtropical high and even formed high temperature weather.

Causes of rainstorm in north China:

First of all, the southwest vortex was formed under the special topography of the Qinghai-Tibet Plateau and certain circulation conditions, which generally appeared in Jiulong, Batang, Deqin, Kangding and Changdu, and may also be formed in the Sichuan Basin. Most of the southwest vortex will dissipate within 36 hours, and a small part will last for 6-7 days.

Moreover, 20% of the southwest vortex can move, of which 70.7% moves eastward and enters the ocean in the Yangtze River basin. Only 2 1. 12% will move to the northeast, and 9. 1% will move to the southeast after passing through many provinces, including North China.

Southwest vortex is a rainfall system. Because of the low air pressure, the warm and humid air around will be involved, the hot air will rise, the temperature will drop and condense into water droplets, resulting in rainfall. So it is raining everywhere in the southwest vortex these days.

Cold vortex is a cold vortex system rotating at high altitude. Its central temperature is lower than the surrounding area, which will also cause rainfall. Generally, it refers to a cold air mass with a height of 500 hectopascals (about 5000 meters). The southwest vortex is generally at the height of 700 hectopascals or 850 hectopascals, which are slightly different.

The low-level jet is an area where momentum, heat and water vapor are highly concentrated, generally below 500 hectopascals. Southwest vortex, cold vortex and low-level jet could have produced a rainstorm respectively, but this time they interacted with each other, and this time, due to the influence of warm and humid airflow south of the periphery of subtropical high, continuous water vapor transport was realized, resulting in a large-scale rainstorm.