Namely solar terms and festivals.

Among the 24 solar terms, Qingming and Solstice are both solar terms and festivals.

Qingming is a combination of solar terms and festivals. Solar terms are "days" and pure natural time, and festivals are "people's time", which is the time choice of social culture. The solstice in winter has both natural and humanistic connotations. It is not only a natural solar term, but also a traditional festival to worship ancestors.