What is the basis for the division of the four seasons in astronomical sense?

Astronomically, the division of the four seasons is based on the seasonal changes of the height of the sun at noon and the length of day and night. The local season with the longest day, the shortest night and the highest noon sun height is summer, and vice versa. Spring and autumn are the transitional seasons between winter and summer.

The four seasons are divided according to the length of day and night and the change of sun height. 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. The traditional method of dividing the four seasons in China emphasizes the astronomical significance of the four seasons, with four of the 24 solar terms as the starting point of the four seasons and bisection and two to one as the midpoint. For example, in spring, the starting point is beginning of spring, the solar line is 3 15, the spring is divided into the midpoint, the long summer is the end point, the solar line becomes 45, and the sun runs 90 on the ecliptic. ?

The division of four seasons in the west emphasizes the climatic significance of the four seasons, taking the bisector of the sun as the starting point of the four seasons, such as spring as the starting point and summer solstice as the end point. These four seasons are one and a half months later than those divided by China. ?

Astronomically speaking, it is more scientific for China to divide the four seasons with four stands. ?

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; Similarly, the winter solstice as the midpoint of winter is also very scientific.