How to determine the date of initial appearance?

The date of first appearance is from summer to the third Geng day in the future to the day before the fourth Geng day in the summer.

The first lodging is the first lodging of "three volts". Because every Geng day is separated by 10 days, the initial lodging time is 10 days. The word "V" in three volts has two meanings. First, it means that Yin Qi was forced by Yang Qi to hide underground; Second, it means the weather is too hot to move. Its climatic characteristics are "high temperature and high humidity".

"Three volts" and "three summers" (summer, summer and midsummer in the 24 solar terms) both represent high temperature and extreme weather, and the curves on the time axis and the temperature axis are basically the same: summer comes, summer comes; When the sky falls, summer is over. The reason why the ancients called the extremely hot day of the year "summer heat" and found a "fu" to accompany it, in addition to the cultural meaning, another important purpose is for health care.

Definition of initial lodging

The word "V" in three volts has two meanings. First, it means that Yin Qi was forced by Yang Qi to hide underground; Second, it means the weather is too hot to move. The sleeping time is determined by the combination of solar terms and dry branch dates. The period from summer to the third Geng day to the fourth Geng day in the future is the "recumbent" period.

The reason why the air humidity is high in dog days is that the southeast wind blows in dog days, while the southeast is the ocean and the air is humid. The humidity of the sea breeze leads to the high humidity in dog days. In dog days, "high temperature and high humidity" is the climate characteristic of southern China. The inland areas in the north are far from the ocean, and the climate is characterized by "high temperature and dryness".