202 1 When does it enter the volt?

Entering the volt means entering the "three volts". There is a folk saying: "The first night falls on the summer solstice", which is the basis for establishing the first autumn. The almanac stipulates that "Voltages will be counted from the third day of the summer solstice", which means that "counting down from the summer solstice" and counting to the third "Geng Day" will begin to decline. The "Geng Day" here refers to the days prefixed with "Geng" in the ancient "Ganzhi Jiri Law".

The so-called heat is in volts, which can be divided into initial, middle and final volts, and its date is determined by the date when the solar terms cooperate with the main branch year. The climate in dog days is characterized by high temperature and high humidity, because the southeast wind blows in dog days, and the air is humid. The humidity of the wind leads to great humidity in dog days.

Date calculation:

In ancient China, heavenly stems and earthly branches combined to record time. The number of heavenly stems is 10, which is A, B, C, D, E, Ji, G, Xin, Ren and Gui, and the number of earthly branches is 12, which is Zi, Ugly, Yin, Mao, Chen, Si, Wu, Wei, Shen, You and Xi. Match heavenly stems and earthly branches, and you will get Jia Zi, Yi Chou, Bing Yin and Ding Mao. Mating 60 times, so it is called 60 flowers.

"Three Geng" is to meet three "Geng" characters, and it will be the first time on the third Geng Day. Because the number of heavenly stems is 10, there is a Geng Day every 10 day, such as Geng Zi Day, Geng Yin Day and Chen Geng Day. 365 days a year (366 days in leap year) is not an integer multiple of 10. One day this year is Geng Day, and next year is not necessarily Geng Day. Due to the uncertain change of Geng Day, the accommodation date is different every year.