After the summer solstice, although the days are getting shorter and the nights are getting longer, the days are longer than the nights in a day, and the heat absorbed by the ground is still more than the heat emitted every day, and the temperature near the ground is getting higher every day. During the "three volts" period, the heat absorbed by the ground is almost less than the heat emitted, and the weather is the hottest.

Therefore, the hottest time of the year does not appear in the summer solstice, but in the "dog days" after the summer solstice.

The time of accommodation is not fixed every year, and the length of accommodation is different, so it is more troublesome to check the almanac. We can simply use the formula of "Xia San Geng" to express the lodging date, that is, from the third Geng day in Xia Hou, the initial lodging is 10 day, the intermediate lodging is 10 day or 20 days, and the final lodging is 10 day.

Mid-lying day for many years

20 1 1 year, and the mid-term festival has 20 days.

20 12 years, with 10 days.

20 13 years, with 20 days in the middle.

20 14 years, with 10 days in midsummer.

20 15 years, with 20 days in the middle.

20 16 years, with 20 days in the middle.