Those solar terms are traditional festivals.

Only Tomb-Sweeping Day is recognized as a traditional festival. In some places, the long summer and winter solstice are also regarded as festivals.

24 solar terms:

Keywords beginning of spring, rain, fright, vernal equinox, Qingming, Grain Rain,

Long Xia, Xiaoman, Mangzhong, Summer Solstice, Xiaoshu and Dashu.

Beginning of autumn, early summer heat, white dew, autumnal equinox, cold dew and early frost.

Beginning of winter, light snow, heavy snow, winter solstice, slight cold, severe cold.