Geography of chencang district

Chencang district is located in the inland area of northwest China, which belongs to the warm temperate zone, semi-humid and semi-arid climate in the mid-latitude continental monsoon region. Due to the complex surface structure and great difference in altitude, the climate in various places is also obvious. The northeast has a Sichuan-Yuan climate, and the southwest and the northern foot of Qinling Mountains have a mountainous climate. Because it is located in the north of the eastern side of the Qinghai-Tibet Plateau, it is controlled by the East Asian monsoon circulation. In winter, affected by polar continental air mass, northerly winds, dry air, low temperature, frequent frost and cold wave invasion. In summer, influenced by tropical ocean air mass, southerly winds prevail, the water vapor content in the air increases, there is more precipitation, the temperature is high and the weather is hot. Spring and autumn are transitional seasons. From March to May, the temperature rises rapidly and the precipitation is insufficient, which is easy to form spring drought. There is more rainfall in autumn, and autumn rain often occurs. Annual average temperature 12.8℃, monthly average temperature10.2℃, extreme minimum temperature-18.4℃ (1991year 65438+February 28th); The average temperature in July was 25.3℃, and the extreme maximum temperature was 465,438+0.7℃ (June 65,438+07, 2006). The monthly average minimum temperature is minus 7.8℃( 1977 1 month), and the monthly average maximum temperature is 33.6℃( 199 1 month). The annual average temperature is 25.5℃. The average annual frost-free period is 224 days, with the longest being 254 days and the shortest being 194 days. The annual average sunshine hours are 19 13.9 hours. The annual average precipitation is 647. 1mm, the annual average rainfall days are 100 days, the maximum is 126 days (1988), and the minimum is 77 days (1997). The maximum rainfall in extreme years is 985.6 mm (20 1 1 year), and the minimum rainfall in extreme years is 383.0 mm (1977). Rainfall is concentrated from May to 10 every year, with the most in August.