Are the 24 solar terms based on the laws of the lunar calendar or the solar calendar?

The twenty-four solar terms are based on the solar calendar.

Lunar calendar is the current traditional calendar in China. According to the national standard "Compilation and Promulgation of Lunar Calendar" drafted by Purple Mountain Observatory of China Academy of Sciences, the first day of the lunar month is the first day of the lunar month, which means that the first day of each lunar month must be the first day of the lunar month. Each lunar month reflects a complete cycle of lunar phase change, so it belongs to the lunar part of the yin-yang calendar. The twenty-four solar terms of the lunar calendar reflect the different positions on the earth's orbit around the sun, that is, the tropic year cycle, so it belongs to the solar calendar part of the lunar calendar.

The 24 solar terms are: beginning of spring, rain, sting, vernal equinox, Qingming, Grain Rain, Changxia, Xiaoman, Mangzhong, Summer Solstice, Slight Summer, beginning of autumn, Early Summer, Millennium, Autumn Equinox, Cold Dew, Early Frost, beginning of winter, Light Snow, Heavy Snow, Winter Solstice, Slight Cold and Severe Cold. This is the twenty-four segments that the ancients divided the whole year according to the change of the position of the sun on the ecliptic and the evolution order of the ground climate.