Heavy rain in Sichuan caused 6 people to lose contact. Why is there a lot of heavy rain this year?

China is a vast country with a great span from north to south and from east to west. The frequency, time and intensity of rainstorm vary greatly. South China has a long rainy season, abundant rainfall and high frequency of rainstorm. The precipitation in the north is relatively small, mainly concentrated in summer. Even in the case of concentrated precipitation in summer, rainstorm is a small probability event. This year, the rain came early and the rainfall was heavy, and the rainfall in many places set a new record. Recently, heavy rain in Sichuan caused six people to lose contact. Why the frequent rainstorm this year has become a topic of concern.

First of all, typhoon weather is one of the reasons for frequent rainstorms this year. When a typhoon crosses the border, there will be heavy rain or heavy rain most of the time. It is also easy to cause floods, resulting in flooding of villages and houses, resulting in huge loss of life and property. The typhoon circulation rainstorm is mainly caused by the spiral cloud belt around the typhoon and the eye wall near the typhoon center. The location of storms varies with typhoons, but they are usually divided into three categories: northeast rainstorm, southwest rainstorm and northwest rainstorm. The rainfall area of typhoon rainstorm is very random. As the typhoon moves, the rain area expands. The intensity of rainstorm is closely related to the intensity of typhoon itself and the moving speed of typhoon.

Since June this year, the continuous enhancement of the western Pacific subtropical high is also one of the reasons that affect the frequent rainstorm weather. The abnormal field of anti-Pacific cyclone prevails in the lower troposphere of the northwest Pacific, and the water vapor transport in the South China Sea and the western Pacific is obviously stronger than that in the subtropical high, which provides sufficient water vapor conditions for continuous precipitation in the southern region. But the continuous rainstorm will have some negative effects. Debris flow is a sudden natural disaster phenomenon, which is common in semi-arid and semi-humid mountainous areas and marginal areas of marine glaciers. Like natural disasters such as earthquakes, debris flow has become a major disaster for economic development and construction in mountainous areas. China has a vast territory, surrounded by mountains and complicated geological structure. There are frequent rainstorms and abundant water resources this year. Debris flow is not only widely distributed, but also has many kinds and frequent activities, which seriously harms industrial and agricultural production and people's lives in mountainous areas.