When is 20 15?

Voltage is divided into initial voltage, intermediate voltage and final voltage, which is called three volts. The dog days are the hottest period of the year, because the nights are getting shorter and shorter, the days are getting longer and longer, and the sunshine is close to direct sunlight. But the summer solstice is not the hottest time, because at this time, a large part of the heat absorbed by the ground radiates at night. But it absorbs more heat and dissipates less heat every day, and it gets hotter every day. It will be the hottest in about 20 days to three volts.

The date of the dog days is from the summer solstice to the third Geng Day, which is the first lie, the fourth Geng Day to the fifth Geng Day is the middle lie, and the second Geng Day after the first Geng Day to beginning of autumn is the last lie. Every Geng day is 65,438+00 days apart, and the number of mid-festival days is not fixed. There are four Geng days from summer solstice to autumn, with 65,438+00 days in the middle, five Geng days and 20 days in the middle.

"Three volts" refers to the first, middle and last three volts, which is about mid-July to mid-August. During the "three volts" period, the ground absorbs almost more heat than it emits, and the weather is the hottest. After that, the heat absorbed by the ground began to be less than the heat emitted by the ground, and the temperature gradually decreased. Therefore, the hottest time of the year generally appears in the "three volts" summer solstice.

From summer to the third watch in the future, the first (10 day), the middle (10 or 20 days) and the last (after beginning of autumn 10 day) are the hottest days of the year.