What is three volts?

Three volts refers to the initial, middle and final volts.

The dog days appear between the slight summer heat and the severe summer heat (from mid-July to mid-August in Gregorian calendar), and the dog days are divided into three days: the beginning, the middle and the end. Dog days are characterized by high temperature, low air pressure, high humidity and low wind speed. "crouching" means being forced to hide underground, and it also means that the weather is too hot to move. The date of the dog days is determined by the coordination of 24 solar terms and the date of the main branch.

Because every Geng day is 10 days apart, the stipulated time of the first day and the last day is 10 days. Because the third Geng Day (the first autumn) after long summer appeared sooner or later, the days of autumn were long and short. The dog days are the hottest, wettest and sultry time of the year.

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".

"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.

incubation period

The time of accommodation is not fixed every year, and the length of accommodation is also different. You need to check the almanac to calculate it. Simply put, we can 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.

In ancient China, the "trunk-branch calendar" was popular, and 60 groups of different names were used to record dates with 10 heavenly stems and 12 earthly branches, which were recycled. The day with the word "Geng" is called "Geng Day". The word "Geng" in Geng Day is the seventh word in "A, B, C, D, E, Ji, G, Xin, Ren, Gui" 10 day, and it is repeated every 10 day.

Starting from the summer solstice, according to the date of trunk, the third Geng day is the first, the fourth Geng day is the middle, and the 1 th Geng day after beginning of autumn is the last. When there are four Geng days between the summer solstice and the beginning of autumn, the middle part is 10 days, and when there are five Geng days, the middle part is 20 days.

It seems that the emergence of Gengri will affect the length of the first half sooner or later, so there will be 30 days in some years and 40 days in some years.

Baidu encyclopedia-dog days