How to divide spring, summer, autumn and winter?

1. Astronomical division method From the astronomical phenomenon, the change of four seasons is the seasonal change of the length of day and night and the height of the sun. In a year, the season with the longest day and the highest sun height is summer, the season with the shortest day and the lowest sun height is winter, and the transitional season between winter and summer is spring and autumn. Therefore, the astronomical division of the four seasons is based on the vernal equinox (March 2 1), summer solstice (June 2 1), autumn equinox (September 2 1) and winter solstice (February 2 1). Namely: spring from the vernal equinox to the summer solstice, summer from the summer solstice to autumn, autumn from the autumn equinox to the winter solstice, and winter from the winter solstice to spring.

2. The meteorological division method of meteorological department: March-May is usually spring, June-August is summer, 9-1 65438+1October is autumn, 12- February is winter,1,April, July and the following year.

3. In the ancient classification, beginning of spring (February 4th or 5th) is beginning of spring, Changxia (May 5th or 6th) is long summer, beginning of autumn (August 7th or 8th) is beginning of autumn, and beginning of winter (165438+1October 8th or 9th) is beginning of winter.

In China, it is customary to divide the four seasons by the month of the lunar calendar. Lunar calendar1~ March is spring, April-June is summer, July-September is autumn, and 10 ~ 12 is winter. The first day of the first month is the first day of the year and the first day of spring, so it is also called the Spring Festival.

Although the above methods are simple and convenient, they all have the same shortcoming, that is, all parts of the country enter the same season on the same day, which is very different from the actual situation in various regions of China. For example, according to the above classification method, March is already spring. At this time, the area south of the Yangtze River is really pink and green, and the spring is strong; The northern part of Heilongjiang is cold and windy, with ice and snow and no spring; People in Hainan Island wear light clothes all summer. In order to make the division of the four seasons consistent with the natural scenery and people's life rhythm, the meteorological department adopted the method of waiting for the temperature to divide the four seasons.

5. Waiting temperature division method

This division is based on waiting time (five days is a waiting time). Take the average temperature as the temperature index to divide the four seasons. Summer begins when the average climate temperature is stable above 22℃, winter begins when the average climate temperature is stable below 10℃, and spring and autumn begins when the average climate temperature is between 10 ~ 22℃. 10℃ to 22℃ is spring, and 22℃ to 10℃ is autumn.