Why is spring warm and autumn cool?

The solar terms in China are divided in this way.

Use summer solstice and winter solstice to distinguish the four seasons.

Beginning of winter is the beginning of the rising of yang in a year, but it is also the beginning of September, and then the temperature gradually rises.

On the other hand, the summer solstice is the opposite, which is the beginning of yin and the release of yang in a year, and then the temperature gradually drops.

So spring is warm and autumn is cold.

On the other hand,

Spring is the process that the earth gradually moves towards perihelion around the orbit of the sun.

Autumn, on the other hand, is the process that the earth gradually leaves the perihelion, which leads to the saying that spring is warm and autumn is cool.

Autumn is the season that needs tonic, so we should also replenish essence in autumn to cope with the arrival of winter, which is the coldest season.