Climatic conditions and causes in Sichuan basin

The terrain of Sichuan basin is closed, and the temperature in winter is higher than that in other areas of the same latitude because the North Qinling Mountains block the cold air. The average temperature in Leng Yue is 3 ~ 5℃ in the north and 5~8℃ in the south, which is 1 ~ 4℃ higher than that in Shanghai, Hubei, Anhui and Guizhou in the south. The extreme minimum temperature in the north of the basin is -8 ~-5℃, and the extreme minimum temperature in the south is -5 ~-2℃. Frost and snow are scarce, and the frost-free period is 280 ~ 350 days throughout the year. In winter, there is constant frost and snow in Wuhan at the same latitude, and Changning, whose basin is located in the Yangtze River basin, is frost-free all the year round. ?

Summer in all parts of the basin begins at the end of May and ends in mid-September. Summer lasts for four months and the temperature is high in the east and low in the west. The average summer temperature in the west of the basin is about 25℃, which is 3-4 degrees lower than that in Shanghai, Wuhan and other cities at the same latitude, but the humidity is unbearable. In the hottest month in the east, the temperature is as high as 26 ~ 29℃, and the local temperature in the Yangtze River basin reaches 30℃. The sunny, hot and high temperature weather in midsummer caused a severe summer drought in the southeast of the basin.

The temperature in the basin is high in the southeast and low in the northwest, with high bottom and low edge. The annual average temperature is 16 ~ 18℃. The active accumulated temperature above 10℃ is 4500 ~ 6000℃ and lasts for 8 ~ 9 months, belonging to the middle subtropical zone. The accumulated temperature in the southeast Yangtze River basin exceeds 6000℃, which is equivalent to the tropical climate of South Asia south of Nanling in China.

The temperature in the basin is high in the east and low in the west, high in the south and low in the north, high in the bottom and low in the edge, and the isotherm distribution is concentric. The temperature in the mountainous area on the edge of the basin has vertical distribution characteristics. The elevation of Emei Mountain and Jinfo Mountain rises by 100 m, and the temperature drops by 0.55℃ and 0.6 1℃ respectively. The average annual temperature at the top of Mount Emei is only 3℃, and the active accumulated temperature above 10℃ is 586℃, which is equivalent to cold temperate zone and sub-cold zone in climate.

Extended data:

The Sichuan Basin can be clearly divided into two parts: marginal mountain and basin bottom, with an area of about 654.38+10,000 square kilometers and160,000 square kilometers respectively. There are many middle and low mountains in the marginal mountainous areas. The elements of the landscape are obviously transitional, such as the composition of animals and plants permeating the components of Central China, Southwest China, Qinghai-Tibet Plateau and North China respectively. Generally, there are 2 ~ 5 vertical natural zones from bottom to top in marginal mountainous areas.

The marginal mountainous areas are the bases of various economic trees and timber forests in Sichuan. There is serious soil erosion in agriculture. There are many hills, low mountains and plains at the bottom of the basin. The surface composition is new and single, sandy mudstone and Quaternary sediments. The climate belongs to the middle subtropical zone, and the heat is much higher than that in the marginal mountainous areas, but the precipitation is not as good as that in the marginal mountainous areas. Vegetation is replaced by artificial secondary forest trees, and the coverage rate is low, and the cultivated land is contiguous. Drought and flood in summer are the biggest disasters in this area.

The internal topography of the basin shows three obvious characteristics, namely, the plain landform in the west of the basin, the hilly landform in the middle of the basin and the landform bounded by Longquan Mountain and Huaying Mountain in the east of the basin.

Baidu Encyclopedia-Sichuan Basin