The beginning and ending time of the initial lodging: from July 1 1 day to July 20, 2023, *** 10 day; The starting and ending time of mid-middling: July 2, 20231day to August 9, 2023, ***20 days; The starting and ending time of the last fall: August 2023 10 to August 2023 19, *** 10 days.
The number of dog days is not fixed, the first and last days are fixed 10 days, only the time in the middle is not fixed, some years are 10 days, and some years are 20 days. Midnight time is determined by how many Geng days there are between the summer solstice and beginning of autumn. If there are four Geng days between the summer solstice and beginning of autumn, the midsection is 10 days, and if there are five Geng days between the summer solstice and beginning of autumn, the midsection is 20 days.
The reason of hot weather in dog days
After the summer solstice, although the direct point of the sun moves southward, the daytime time is gradually shortening, but the heat radiated from the sun to the ground is still greater than that radiated from the ground to the air, and the heat on the ground will increase day by day, and the heat absorbed by the ground will accumulate to the maximum during the dog days.
Secondly, the southeast wind mainly blows from the Pacific Ocean during the dog days, and the sea breeze causes high humidity during the dog days, while the specific heat capacity of water is large, and humid air can absorb a lot of heat, so it is often very stuffy and prone to "heatstroke" during the dog days.
Finally, during the three-volt period, most parts of China are controlled by subtropical high, which is beneficial to sunlight and ground radiation warming, which is also the main reason for the hot weather during the three-volt period.