What are the main characteristics of temperature and precipitation in Changsha City?

The climate characteristics of Changsha are: cold winters and hot summers, four distinct seasons; short springs and autumns, long winters and summers, which fully reflect the unique characteristics of the subtropical continental wind climate type.

< p> Spring: The first climate characteristic is rapid warming and large temperature changes. "One day in spring, the water and the heat are three times hotter" is a proverb known to both young and old in Changsha. From the average temperature in March to 10℃, the average temperature in May is 22℃. In just two months, the temperature rose by 12°C, with an average monthly increase of 6-7°C. At the same time, not only did the temperature rise rapidly, but it also changed greatly. For example, the temperature in April, according to 30 years of statistical data, the lowest monthly average temperature was 13.6 ℃, with a maximum of 21.1 ℃, a difference of nearly 8 ℃. Another example is that the lowest temperature on April 5, 1969 was 2.5 ℃, and the highest temperature on April 10 of the same year was 33.4 ℃, with a temperature difference of more than 30 degrees in 5 days. Therefore, "late spring cold" is a common phenomenon in Changsha. Rapid warming is beneficial to the sowing of crops, but large temperature differences bring adverse effects. The second characteristic of Changsha's spring is continuous rain and humid air. March in Changsha The average number of rainfall days (daily rainfall equal to or greater than 0.1 mm) in May is 52.8 days, accounting for more than 35% of the total rainfall days in the year (151.2 days). In many years, there are continuous rainfalls of 15-20 days. , so the precipitation from March to May accounts for more than 40% of the total precipitation in the year. Cloudy days in these three months (daily average total cloud cover is greater than 80%) account for more than 31% of the total cloudy days in the year, and the relative humidity is Between 83% and 84%, it is the season with the highest relative temperature throughout the year. In short, Changsha’s spring rain is famous throughout the country. Summer: Changsha’s summer is well known to be long and hot, lasting four and a half months, making it the longest season in the year. .It is also the season with the highest temperature in the whole year. From June to September, the average ten-day temperature is 25℃, and from late July to late August, the average ten-day temperature is above 29℃. According to records, on August 10, 1934, Changsha Customs measured The highest temperature measured at the Tianxin Park Observation Field of the waiting station is 43℃, which is the limit of high temperature in Changsha. The highest temperature since 1949 is 40.6℃ measured on August 13, 1953. This situation is relatively rare in the country. Changsha Day There are 94 days in the year when the average temperature is higher than 30℃, of which 84 days occur in summer. The daily average temperature is higher than 35℃ for more than one month in the year, basically concentrated in August. Since Changsha is located in the Xiangjiang River Valley, the terrain is relatively The temperature is low, the relative temperature is relatively high, and the heat is even more intense. Therefore, Changsha, Chongqing, Wuhan, and Nanjing are called the four great furnaces in the Changsha Basin. Changsha’s summer is also characterized by uneven precipitation and irregular droughts and floods. Most of the heavy rain days are concentrated in the three months of May, June and July. In the 30 years from 1951 to 1980, there were 110 days of heavy rain in Changsha, of which May 23, June 29 and July 20 were the worst days. More than 65% of the total. However, rainfall varies greatly from year to year. For example, the total average rainfall in late June was 69.8 mm, but in 1969 it was as high as 384.8 mm, while in 1975 there was no rain. Another example is the rainfall in early July. The precipitation was 41.4 mm, but it was 226.7 mm in 1965, and there were five years without rain. The result of uneven precipitation is bound to cause waterlogging or drought, but due to high temperatures and sufficient rain, Changsha's summer still provides good conditions for the growth of crops. Favorable climatic conditions. Autumn: Autumn in Changsha is characterized by less rainfall and crisper air. Autumn and winter are the driest seasons in Changsha. According to statistics, the average precipitation from late September to mid-November is only 23.6 mm, less than three points of spring. First, there have been many years in history where there was no rain for nearly 40 days, and the characteristics of autumn dryness are very obvious. In addition, although autumn in Changsha is shorter, it has more sunny days. According to statistics, the average annual low cloudiness in Changsha There were 136.2 days of sunny days with a quantity less than 2, and September to November accounted for 41.5 days, accounting for one-third of the total in the whole year. The temperature during this period is also more suitable, changing from hot summer to cool autumn, but the temperature again The temperature is slightly higher than that of spring, so Changsha is known as the "October Xiaoyangchun" among the people. Changsha's "golden autumn season" not only shows the picturesque scenery of "thousands of mountains are red and the forests are dyed", but also shows "the frost and dew steaming thousands of times". The harvest atmosphere of "ripe trees, waves surrounding the wind shaking the continent with fragrance" and "jellyfish see seedlings everywhere, and every hut is referring to wheat autumn" reproduces a mature beauty everywhere. What is slightly lacking is that autumn has gone again in a hurry, It is a bleak winter. Winter: There is no severe cold in Changsha in winter and little rainfall. The average monthly temperature in winter is mostly above 5℃, and the monthly average temperature in the coldest January is 1.6℃, with the highest temperature being 8.6℃. The temperature varies throughout the day. There are only 19.9 days on average in winter when the weather is below 0°C and causes frost or freezing. Although there are extremely low temperatures on rare occasions, such as the lowest temperature reaching -11.3°C on February 9, 1972, and reaching -11.3°C on January 31, 1969. -9.5℃. However, the average daily temperature is only 1.3 days per year when the average temperature is -5℃, and there is no severe cold period when the average temperature is less than 0℃. Although the precipitation in Changsha in winter only accounts for 16% of the whole year, it is December, the month with the least rainfall, has an average monthly rainfall of 45.3 mm, which is more than Nanjing (29.4 mm) in the lower reaches of the Yangtze River and Guangzhou (24.7 mm) in the Pearl River Delta. This rainfall is enough for the growth of overwintering crops. Because of the rain It is moderate and not too cold, so the winter in Changsha is not desolate. Evergreen broad-leaved trees such as camphor and ligustrum are still green, just like the Tang Dynasty Du Xunhe's poem "Boating on the Xiangjiang River with Friends in Late Winter" goes: "Boating with residual wax" The most popular place is Xiaoxiang." Changsha's climate, with four distinct seasons, not only contains the vitality of life, but also the struggle with nature. The ups and downs of the environment have cultivated the pepper character and fighting spirit of Changsha people. Since then, this land It has been more than thousands of years since humans appeared on the land, and it is still flourishing today.