What does it mean to count volts?

The meaning of several volts is as follows:

The dog days began on the third Geng Day after long summer; It also refers to entering the dog days.

Question 1: How to calculate a few volts? What is its origin? When did you start counting volts? As the saying goes, "it's cold in three or nine days, but hot in three days." On the first day of my first night, I began to enter the hottest period of the year. The "Ninth Five-Year Plan" is counted from the winter solstice, but for the "several volts", the start date of the first autumn is always changing every year, which is calculated according to the "trunk and branch calendar".

The ancient book Qunfangpu said: "This is not the end of summer." Because after the slight heat, the hottest dog days of the year are coming. The dog days are the hottest time of the year, with concentrated rain and sunset. Hanshu? Notes on Sacrifice to the Suburbs said: "Sleeping means that Yin Qi will get up, but he can't get up because of the setting sun. So, it is hidden, and it is because of the name. "

Question 2: What do you mean by a few days? Every summer from mid-July to mid-August at 5: 00, it is a unique "three volts" solar term in China. "crouching" means being forced to hide underground, which is the hottest time of the year. Starting from the summer, according to the arrangement of dry and branch days, the third Geng Day is the first month. The fourth Geng Day was in the middle, and the first Geng Day after beginning of autumn was the last.

Question 3: What do you mean by dog days? The dog days appear between the light summer heat and the heavy summer heat, and are the days with the highest temperature, humidity and sultry weather in a year. The so-called "dog days" refers to the "dog days" of the lunar calendar, which is the hottest period of the year.