What is three volts?

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

"Dog days" is the hottest day in a year. "Dog days" means that Yin Qi is forced to hide underground by Yang Qi, and it appears from mid-July to mid-August in the solar calendar every year. According to the climate law of China lunar calendar, predecessors have stipulated that the third Geng day from long summer to the future is the first day, the fourth Geng day is the second day, and the first Geng day after beginning of autumn is the end, and the voltage is ten days * * * thirty days.

In some years, the "summer" is 20 days, while * * * is 40 days. The dog days are determined according to the ancient method of "keeping records of the sun by cadres and branches". Every summer to the future, the third Geng Day (referring to the day with the word "Geng" on the trunk and branches) is the beginning period, the fourth Geng Day is the middle period, and the first Geng Day after beginning of autumn is the end period, collectively referred to as the dog days.

High temperature and extreme weather

According to the solar calendar, it appears from mid-July to mid-August, when most parts of China are the hottest season of the year. The dog days are the hottest time of the year, with concentrated rain and sunset. 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.

The southeast is the ocean, the air is humid, and the humidity of the sea breeze causes the humidity in the dog days. The dog days are characterized by high temperature and high humidity, which 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" (slight summer heat, great summer heat and great summer heat in the 24 solar terms) all represent extreme weather with high temperature, and the curves on the time axis and the temperature axis are basically the same.