Climatic characteristics of xuanwei county.

Xuanwei is located in the northeast of Yunnan Plateau, with high mountains and deep valleys criss-crossing and high altitude difference. Summer, autumn, winter and spring are influenced by ocean air mass and continental air mass respectively, forming a low-latitude plateau monsoon climate with multiple climatic zones of north subtropical zone, south temperate zone and middle temperate zone. Its main characteristics are: no severe cold in winter, no coolness in summer, small annual temperature difference, large daily temperature difference and unclear four seasons; Drought in winter and spring, rainy in summer and autumn, concentrated precipitation, clear wet and dry, and large annual change rate; Sufficient sunshine, low accumulated temperature and great regional differences.

Annual average temperature 13.4℃, highest annual average temperature 14.6℃, lowest annual average temperature 12.7℃, annual temperature difference 1.9℃. The average sunshine for many years is 20 18.5 hours, with sunshine percentage of 47%. The maximum sunshine hours is 2369. 1 hour, and the minimum is 1805. 1 hour, with a range of 564 hours. The largest month is 229.9 hours in March, and the smallest month is September 126.2 hours.

The spatial distribution of precipitation in Xuanwei is quite different. The annual precipitation from southeast to northeast is1200 ~1400 mm; Cold Liangshan area is above 1600 mm; The annual precipitation in the western region is 850 ~1000 mm; Northwest 1000 ~ 1200mm. In the dam area with Xuanwei as the center, the average precipitation for many years is 975.2 mm, and the precipitation time distribution is uneven, and the whole year is divided into obvious dry and wet seasons. 165438+ 10 to mid-May of the following year, mainly controlled by continental air mass, with low temperature, sunny days, abundant sunshine, large evaporation and little precipitation. The precipitation during the period is 164.3mm, accounting for 16.8% of the total annual precipitation, which is a dry season. From late May to 65438+ 10 every year, affected by southwest monsoon and southeast monsoon, the humidity is high, with more clouds and less sunshine, and the precipitation increases sharply. During this period, the average precipitation was 8 15.7 mm, accounting for 83.2% of the annual precipitation, especially in June-July, when the average precipitation was 405 mm, so there were more floods in June-July. The maximum annual precipitation is 1304.8 mm, and the minimum is 657.4 mm. ..

Xuanwei is to the south, with an average annual wind speed of 3.9 m/s. Because of Xuanwei's high altitude, the mountains run north and south and are windy. The average frost days in Xuanwei are 38.7 days, the longest is 6 1 day and the least is 23 days. The average first frost period is165438+1October 4th, and the final frost period is March 30th. The annual average snowfall is 10.6 days, the longest snowfall is 27 days, and the minimum snowfall is 1 day.

There are many meteorological disasters in this city, such as drought, flood, low temperature, frost, hail, wind disaster, lightning and so on.

The main climatic characteristics of Xuanwei in 2004 are high annual temperature, slightly more annual precipitation and normal sunshine. The thermal conditions are good and the precipitation is evenly distributed. Annual average temperature13.7&; Ordmc, a decrease of 0.9&; Ordmc, 0.3 higher than the multi-year average; ordmc； Annual precipitation 1.023.8 mm, slightly more than many years, 258.6 mm more than the previous year and 5 1.8 mm more than the average precipitation for many years; The annual sunshine hours are 1925.9 hours, which is a normal year. From June to February in 65438, the temperature was high, but the cold air activity was frequent, and there was a heavy snow process on February 7 ~ 8. From March to May, the temperature is normally low and the precipitation is normal. There was a strong cold wave in spring from March 3 to 7, and it was affected by strong cold air from April13 to April15, resulting in low temperature and rainy weather. The daily average temperature dropped to about 10℃ ~ 6℃, and the rainy season began in May of 12, one year earlier. Warm conditions are good from June to August, with low temperature and rainy weather on June 5- 12, high temperature and sunshine after July, and high temperature and high humidity in August. In September-165438+10, the temperature is high, the precipitation is slightly less, and the sunshine is normal; There was a lot of precipitation in 65438+February, but the temperature was high, and there was a snowstorm on the 27th.