The first classification method:
The traditional division method of four seasons in China takes four solar terms (beginning of spring, long summer, beginning of autumn and beginning of winter) as the starting point of four seasons, and bisection and two to two as the midpoint. For example, in spring, beginning of spring is the starting point, the solar meridian is 315, the spring is the midpoint, long summer is the end point, the solar meridian becomes 45, and the sun runs 9 on the ecliptic. This is a traditional and common method.
The second classification:
Astronomical classification (that is, western classification) emphasizes the climatic significance of the four seasons, and takes the equinox to the sun as the starting point of the four seasons, such as spring as the starting point and summer solstice as the ending point. These four seasons are one and a half months later than the traditional four seasons in China.
The third classification method:
Climate statistics method, because January is generally the most Leng Yue, so
spring is March, April and May;
in summer, June, July and August;
autumn is September, October and November;
in winter, it is December, January and February.
This classification of four seasons is more suitable for temperate regions with distinct seasons.
Because China is vast in territory and abundant in natural resources, and the north-south span is large, it is impossible to judge the division of four seasons simply by 24 solar terms or months. For example, Suizhou City spans 31 degrees 19 minutes to 32 degrees 26 minutes north latitude and 112 degrees 43 minutes to 113 degrees 46 minutes east longitude. According to the distribution of cold and hot, I personally think that the four seasons in Suizhou should be:
Spring: March, April
Summer: May, June, July and August
Autumn: September and October
Winter: November, December, January and February
The fourth classification:
In order to. It is also stipulated that the period when the average temperature is greater than or equal to 22℃ is summer, the period when it is less than or equal to 1℃ is winter, and the period between 1℃ and 22℃ is spring or autumn. According to this standard, the four seasons are divided, and the seasons in the mid-latitude area are consistent with the climate, while the temperature changes in spring, summer, autumn and winter in the low-latitude area and near the polar regions are not obvious. At the same time, in the mid-latitude area, the length of each season is different. This is the four seasons. For example, Beijing has 55 days in spring, 13 days in summer, 5 days in autumn and 157 days in winter. This method can be combined with the specific climate and agriculture in various places, so it is widely used.
criteria for entering spring: the daily average temperature is higher than 1 degrees Celsius for five consecutive days;
criteria for entering summer: the average daily temperature is higher than 22 degrees Celsius for five consecutive days;
criteria for autumn: the average daily temperature is lower than 22 degrees Celsius for five consecutive days;
winter standard: the average daily temperature is below 1 degrees Celsius for five consecutive days.
calculation method of daily average temperature:
at 8: , 14: , 2: and 2: in a day, the temperature measured in four time periods is divided by four, which is the daily average temperature of a day.
— from the network.