The geography and climate of duchang county.

Duchang is located in the subtropical humid monsoon climate zone, influenced by Poyang Lake, with mild climate, abundant rainfall, abundant sunshine, sufficient heat, short ice age, long frost-free period, short spring and autumn season and long summer and winter. According to meteorological records, the first day of spring appears on March 24th on average (the first day when the daily average temperature passes 10℃ is beginning of spring), and the duration is about 65 days. The first day of summer appears on May 28th on average (the first day when the daily average temperature stably passes 22℃ is the first day of summer), and the duration is about 1 19 days. The average start date of autumn appears on September 24th (the day after the average daily temperature stably passes 22℃ is the start date of autumn), and the duration is about 59 days. The start date of winter appears on average at165438+1October 22nd (the day after the average daily temperature passes 10℃ is the start date of winter) and lasts about 122 days. At the turn of winter and spring, it is often hit by cold waves and the weather is changeable. At the turn of spring and summer, it is alternately controlled by cold and warm air masses, and it continues to be rainy and foggy in winter; At the turn of summer and autumn, the subtropical high stays for a long time, with sunny and hot weather and little rain. In autumn and winter, the cold air from the north invaded the south strongly, and the temperature plummeted and the frost was cold.

Temperature: the annual average temperature is 17. 1℃, and the range of change is between 16℃ and 17℃. The daily temperature difference is 7.65438 0℃. 65438+ 10 is the coldest month with an average temperature of 4.4℃, and the hottest month is July with an average temperature of 29.3℃. The order of monthly average values is: 4.4℃, 6.0℃, 10.7℃, 16.5℃, 2 1.5℃, 25.4℃, 29.3℃, 29. 1℃, 24.6.

Accumulated temperature: the annual average active accumulated temperature ≥℃ is 5800-6500℃.

Ground temperature: the annual average surface temperature is 19.5℃. 4. Frost-free period: the average frost-free period for many years is 26 1 day, the longest frost-free period is 300 days, and the shortest is 227 days. The average frost-free period of the whole year is 27 1 day, with the longest 300 days and the shortest 239 days.

Sunshine: the average sunshine hours for many years is 2076.3 hours, and the sunshine rate is 47%.

Precipitation: 1952- 1958 precipitation 1728.28 mm, 1959- 1989 average precipitation139/0.5 mm.

Evaporation dryness: annual average evaporation 1572.5 mm, annual average evaporation greater than precipitation, relative humidity 78%, dryness 1.27.

Catastrophic weather: the main disastrous weather and natural disasters are cold in spring, small-scale cold, wind and hail, plum rain, autumn drought, rotten autumn and cold dew wind; Flood, drought, wind and hail, pests and diseases. Other disasters, such as low-temperature freezing snow disaster, plague, earthquake, etc., generally have low frequency, small affected area and light losses.