How is it generally calculated to enter nine in winter and lodging in summer?

1. In China, March 9 is counted from the winter solstice of the lunar calendar. The first day of the winter solstice is the first day of entering nine, and every nine days is a nine. As the saying goes: 1929 don't shoot, walk on the ice in 3949, and watch the willows by the river in 59 and 69. This sentence says that March 9 is the coldest stage in winter.

The dog days in summer are the hottest stage. The dog days appear in hot summer and early autumn, which is the hottest and muggy day of the year. It is still very troublesome. For example, from summer to the third Geng day in the future, the head falls (the first), the fourth Geng day falls (the second), and the first Geng day after beginning of autumn falls (the third), each falling for ten days * * * thirty days. In some years, the "mid-crouch" is 20 days, while * * * is 40 days.