Are the twenty-four solar terms solar or lunar?

Gregorian calendar, of course, that is, solar calendar. Let's take a few solar terms that impress everyone: you see that the vernal equinox, autumnal equinox, winter solstice and summer solstice are all between 2 1-23 days in the Gregorian calendar; For another example, Tomb-Sweeping Day's qi is always on the 4th-6th day of the solar calendar, which has nothing to do with the lunar calendar (that is, the calendar generated by the moon revolving around the earth). The twenty-four solar terms are based on the earth's revolution around the sun, and the Gregorian calendar is the calendar of the earth's revolution around the sun. The lunar calendar is related to the ebb and flow of the full moon.