What do you mean by initial crouching?

The first autumn is from the third Geng day to the day before the fourth Geng day. Because every Geng day is separated by 10 days, the initial lodging time is 10 days. Its climatic characteristics are "high temperature and high humidity".

The dog days, which appear between the summer heat and the summer heat, are the period with the highest temperature, the highest humidity and the most severe sultry heat in a year. "V" means being forced to hide underground. There are three kinds of fu: initial fu, middle fu and final fu, and their dates are determined by the solar terms and dates of the dry branch calendar. After "entering the volt", many places in the country will enter the continuous high temperature mode.

The difference of dog days:

The length of dog days mainly lies in the difference between middle and next days. Because the third Geng day (the first autumn) after the summer solstice solar term occurs at different times every year, the number of days in the middle autumn is also different. The incubation time is long or short, which may be 10 day or 20 days. So there are two situations: some years are 30 days in dog days, and some years are 40 days.