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What are the four seasons divided according to?

The basis for the division of four seasons

The division of four seasons is based on the length of day and night and the change of sun height (temperature).

Start time of four seasons

(1) astronomical season

The division of the four seasons is based on the apparent position of the sun on the ecliptic and bounded by the bisector, the second solstice or the fourth day. However, the dividing points used by eastern and western countries to divide the four seasons are not exactly the same.

(1) Traditional Four Seasons in China:

The traditional four seasons in China emphasize the astronomical significance of the four seasons, starting from Li Si (beginning of spring, Changchun, beginning of autumn and beginning of winter) among the 24 solar terms, and taking the two poles (vernal equinox and autumnal equinox) and the two solar terms (summer solstice and winter solstice) as the midpoint of the four seasons. Every season, the sun runs 900 degrees on the ecliptic. For example, in spring, beginning of spring is the starting point and the meridian of the sun is.

3 150, spring is divided into midpoint, solar calendar is 00, long summer is the end, and solar calendar is 450. From early spring to long summer, the sun runs 900 times on the ecliptic. This is a traditional and commonly used method. The four seasons correspond to the Gregorian calendar (Gregorian calendar): February 3rd or 4th or 5th in beginning of spring, May 5th or 6th or 7th in long summer, August 7th or 8th or 9th in beginning of autumn, and beginning of winter165438+1October 6th or 7th or 8th. So there are also simple spring in February-April, summer in May-July, summer in 8- 10, and winter in1-1. Almost corresponds to the division of the lunar calendar. It is in line with the saying that "spring hits six or nine heads (beginning of spring on the first day of June 9)".

(2) Western Four Seasons

The division of four seasons in the west emphasizes the climatic significance of the four seasons, with the vernal equinox (vernal equinox and autumnal equinox) and summer solstice (winter solstice) as the starting points of the four seasons, and the vernal equinox (March 2 1 or so), summer solstice (June 22 or so), autumn equinox (September 23 or so) and winter solstice (1so). Spring begins with spring and ends with summer solstice; Summer begins with summer solstice and ends with autumn. Autumn begins with autumn and ends with the winter solstice; Winter begins with the solstice of winter and ends with spring. The start time of the four seasons is 45 days later than the traditional start time of the four seasons in China.

Astronomically speaking, China's division of four seasons based on four stands is more scientific.

At the equinox, the length of day and night and the height of the sun around the world are equal to the annual average, which has the typical characteristics of transition from maximum (or minimum) to minimum (or maximum). Therefore, it is very reasonable to regard the vernal equinox as the midpoint of spring and the autumnal equinox as the midpoint of autumn. In summer, the day is the longest and the night is the shortest. On the day of summer solstice, the height of the sun is the highest and the surface gets the most solar energy. Therefore, it is very reasonable to take the summer solstice as the midpoint of summer; The winter solstice has the shortest day and the longest night, and the sun is the lowest in height and the solar energy on the ground is the lowest. Therefore, it is also very scientific to regard the winter solstice as the midpoint of winter.