Climatic conditions in Anhui Province

Anhui is located in the mid-latitude zone. Under the comprehensive influence of solar radiation, atmospheric circulation and geographical environment, Anhui has a transitional climate from warm temperate zone to subtropical zone. In the climate division of China, the north of Huaihe River belongs to temperate semi-humid monsoon climate, and the south of Huaihe River belongs to subtropical humid monsoon climate. The main climatic characteristics are: obvious monsoon, distinct seasons, mild climate, moderate rainfall, changeable temperature in spring, fresh air in autumn, obvious plum rain and concentrated rain in summer. On the whole, Anhui has superior climatic conditions and abundant climatic resources. Abundant light, heat and water resources are beneficial to the development of agriculture, forestry, animal husbandry and fishery. However, due to the transitional characteristics of the climate, cold and warm air masses in the north and south cross frequently, the weather is changeable, the annual precipitation changes greatly, and natural disasters such as drought, waterlogging, wind, freezing, frost and hail often occur, which has adverse effects on agricultural production.

First, the monsoon is obvious and the four seasons are distinct.

There are four distinct seasons in Anhui province, and the climate of "warm spring", "summer inflammation", "cool autumn" and "cold winter" is obvious. If the four seasons are divided according to the average climate temperature, the average climate temperature < 10℃ is winter, >; 22℃ is summer and 10-22℃ is spring and autumn, so the distribution of four seasons in Anhui Province is roughly as follows: two months in spring and autumn, four months in Xia Dong, long in winter and summer, and short in spring and autumn. Because of the obvious climate difference between north and south, Huaibei is longer in winter than in summer, and Jiangnan is longer in summer than in winter. The start date of the season is from south to north in spring and summer, and from north to south in autumn and winter, with a difference of about 5- 15 days, with the largest difference in spring and the smallest difference in summer.

Second, the climate is mild and the rainfall is moderate.

The average annual temperature in Anhui Province is between 14─ 17℃, which belongs to a mild climate type. In winter, the average temperature in 65438+ 10 is between-1 ~ 4℃, and in summer, the average temperature in July is around 28 ~ 29℃, which is lower than 30℃ all over the year, so the continental climate is not obvious. Except for a few years, the cold and hot periods are generally short. The annual precipitation in the whole province is between 750- 1700 mm, which has the characteristics of more in the south and less in the north, more in the mountains and less in the plains and hills. Huaibei is generally below 900 mm, Jiangnan, western Jiangnan and Dabie Mountain are above 1200 mm, and the rainfall lines such as 1000 mm run through the middle of Jianghuai hilly area. Precipitation in mountainous areas generally increases with height, and the average annual rainfall in Guangmingding of Huangshan Mountain reaches 2300 mm. According to the national precipitation distribution map, the rainfall in Anhui Province is moderate, which can meet the needs of crop growth and development in general years.

Third, the spring temperature is changeable, and the autumn is crisp.

April and May are the transitional periods between winter wind direction and summer monsoon. The north-south airflow competes with each other, advancing and retreating freely, the front belt moves north and south, the cyclone activity is frequent, and the weather and climate are changeable. Therefore, cold and warm, rainy and sunny are a major feature of the spring climate in our province. The temperature rise in spring is unstable and changes greatly every day. The temperature in spring is lower than that in autumn, and the spring rain is more than the autumn rain. The precipitation in March, April and May accounts for about 20-38% of the annual precipitation, increasing from north to south. The rainy season in the south of the Yangtze River comes early, and the annual rainfall concentration period is in April, May and June. Spring rain is more than summer rain in Jiangxi, Tunxi and Qimen. In spring, the low temperature and abundant spring rains, especially the long-term low temperature and continuous rain, are unfavorable to the seedling growth of spring-sown crops such as early rice and cotton. In autumn, in addition to the cold high pressure on the ground, the subtropical warm high pressure is still maintained at high altitude, and the atmospheric stratification is relatively stable, and the autumn is crisp and sunny.

The precipitation in September-165438+ 10 only accounts for about 15-20% of the annual precipitation, with little difference between north and south. Therefore, autumn drought and autumn drought often occur in various parts of Anhui Province. Several years later, in the process of summer monsoon retreat and winter monsoon strengthening, cyclones and fronts bring autumn wind and autumn rain, which is not good for autumn harvest and autumn planting.

Fourth, the plum rains are remarkable and the summer rains are concentrated.

The longest meiyu period (1954) is 57 days, and the amount of meiyu exceeds 1─2 times of the precipitation in normal years, resulting in a once-in-a-century flood disaster. In 1958, 1959, 1966, 1967, 1978, 1994, the short or empty plum rains caused severe drought or even drought that never happened in a century. It can be seen that the amount of plum rain has a great relationship with drought and flood disasters and agricultural production in Anhui Province.

Summer rain concentration is one of the characteristics of monsoon climate, which is the result of the slow movement of rain belt from south to north. The concentration of summer rain in our province gradually increases from south to north, and the rainfall in June, July and August accounts for about 33-60% of the annual precipitation.

The summer rainfall along the Yangtze River and south of the Yangtze River is almost the same. The summer rainfall between the Yangtze River and Huaihe River accounts for 40-50%, and most areas in Huaibei account for more than 50%. Summer is the season when crops grow vigorously and the water demand is large. Summer rainwater concentration is beneficial to crop growth, but if it is too concentrated and the rainfall is too large, it is prone to waterlogging, which is harmful to agricultural production and people's lives.