Why are the 24 solar terms calculated according to the solar calendar?

First of all, the lunar calendar is not a simple lunar calendar, but a combination of yin and yang. So there was a solar calendar in ancient China, which was the twenty-four solar terms.

In ancient times, our ancestors set the moon according to the lunar calendar, that is, the time from the first night when we couldn't see the moon (new moon) to the second night when we couldn't see the moon was one month (about 29.53 days when we saw the new moon). Its advantage is easy to observe, but its disadvantage is that it can't reflect the changes of seasons and phenology.

In order to combine the advantages of lunar calendar and solar calendar, our ancestors created the lunar calendar. Divide a year into twelve solar terms and twelve neutral terms (now collectively referred to as twenty-four solar terms). Every two solar terms, the sun runs at an interval of fifteen degrees and the time interval is about fifteen days. Therefore, the essence of the 24 solar terms is the 24 fixed positions of the sun's apparent motion on the ecliptic, which naturally corresponds to the solar calendar.