Geographical environment of Xiaochang county

Xiaochang County is located in the north of the Yangtze River, in the south of Dabie Mountain and in the north of Jianghan Plain. Located at the intersection of Dabie Mountain and Jianghan Plain, it controls the Central Plains in the north and Wuhan in the south, belonging to the core circle of Wuhan city circle.

Xiaochang County is located in the northeast of Hubei Province, south of Dabie Mountain and north of Jianghan Plain. It is connected to huangpi district in the east, Yunmeng County and Anlu City in the west, Xiaonan District in Xiaogan City in the south and Dawu County and Guangshui City in Suizhou City in the north. The ground span is north latitude113 45'-16 5438+0415', and north latitude 312'-3146'; It is 37 kilometers wide from east to west and 45 kilometers long from north to south, with a total land area of 12 17 square kilometers, accounting for 13.4% of the city's total land area, accounting for 0.644% of the province's total land area and 0. 124‰ of the country's total land area. Four different seasons

Xiaochang has a subtropical monsoon humid climate. Four distinct seasons, abundant heat, abundant rainfall, long frost-free period, with the characteristics of light, heat and water reflection in the same season. In spring, cold wave activities are frequent, the temperature fluctuates greatly, and sunny and rainy alternate. In late spring and early summer, the climate is mild, the rain is abundant and the wind direction is changeable. There are often "plum rains" in summer, generally entering the plum rain season in mid-June and coming out in mid-July. After plum blossom, it is often hot and dry, and southerly wind (Nanyang wind) blows at the same time, which is easy to lead to drought and flood disasters. Autumn is sunny and rainy, and autumn cold begins to attack. In late autumn, there is "Xiaoyangchun" weather with crisp autumn air. In winter, the north wind prevails, it is cold and rainy, and there are often ice and freezing injuries.

The seasonality is obvious

The wind direction changes obviously with the seasons. There are northerly winds in winter, spring and autumn, and southerly winds in summer, with an annual average wind speed of 2.6m/s, which is closely related to seasons, with the maximum wind speed of 2.7m/s in spring. The lowest wind speed in autumn is 2.3m/s. The maximum average wind speed in April and July is 2.9 m/s, and the minimum wind speed is 2.3 m/s in 65438+ 10. In a day, it is mostly northeast wind in the morning and southerly wind in the afternoon.

Wind, this phenomenon is particularly obvious in late spring and early summer; The wind speed is the smallest in the morning and the largest in the afternoon; Due to the influence of topography, the maximum wind speed changes greatly. The wind speed in some areas can reach 27 m/s (equivalent to 10 gale), and the gale above 8 in the county has an average of 14 days. Cold dew wind generally appears in 10 every year. According to the analysis of meteorological data from1993 to 2003, the shortest frost-free period is 193 days and the longest is 286 days. The average frost-free period is 248 days, accounting for 67.9% of the total days of the year. The first frost period is generally in the middle of 1 1 month, and the final frost period is generally in the middle of March.

Sunshine temperature

The sunshine hours are 4427.2 hours, and the daily average is between10.1~14.1hour. Due to the cloud cover, the actual sunshine hours in the whole year are about 2 150 hours. The month with the highest sunshine percentage is August, reaching 66.7%; The lowest in March was 35.9%. The average over the years is 48.5%. The total solar radiation in one year is 1 1 1.5 kcal/cm&; sup2。 Its intensity ratio is: it increases month by month in the first half of the year and decreases month by month in the second half. The highest values in a year appear in July and August, and the lowest values are 1 and 12. The annual effective radiation is 52.5 kcal/cm&; sup2。 The general trend of seasonal distribution is: summer is more than winter, spring is higher than autumn, July-August is the most abundant, and 1 month and 65438+February are the weakest. The annual average temperature in Xiaochang is 16. 1℃, and the annual variation forms a single peak type, that is, January is the coldest in a year, with a monthly average temperature of 3.2℃ and an extreme minimum temperature of-191year of 65438+2. It is the hottest in July, with an average temperature of 28.5℃ and an extreme maximum temperature of 38.5℃ (1August 9, 967). The annual average temperature is 25.3℃, and the annual extreme temperature is 53.4℃. The general feature of daily variation of temperature is that the highest temperature appears around two o'clock in the afternoon, the lowest temperature appears around sunrise in the morning, and the daily temperature difference generally varies between 7℃~ 10℃.

Precipitation distribution

The annual average precipitation is about 1 130mm. Rainfall distribution has obvious seasonal variation. According to the statistics of Garden Rainfall Station 1957 ~ 2000, the average rainfall in spring (March ~ May) is 330. 1mm, accounting for 30.8% of the annual rainfall. The average rainfall in summer (June-August) is 459.6 mm, accounting for 42.8% of the annual rainfall. In autumn (September ~ 65438+1October), the average rainfall is 195. 1mm, accounting for 18.2% of the annual rainfall. The average rainfall in winter (65438+February ~ February) is 87.4mm, accounting for 8.2% of the annual rainfall. The annual precipitation is the largest in six years (1963, 1969, 1980, 1983, 1987, 1996). The annual rainfall is less than 800mm in five years (1966, 1978,198/kloc-0,1200 1), and the year with the least annual rainfall is 200/kloc.