21, summer solstice. Shortly after the summer solstice, it was the dog days. As the saying goes, "three gengs of the summer solstice will count the number of volts". This means that from the beginning of the summer solstice, the third Geng day will enter the first ambush, that is, the first day of the ambush. Astronomy experts said that the third "Geng day" counted from the summer solstice this year is July 16, which means that this day is the time to fall. Poster production: fangjinyang Volt marks the hottest period of the year. As the saying goes, "the heat is three volts". Lin Yuan, a member of the Chinese Astronomical Society and an expert in astronomical science popularization in Tianjin, said that the date of Fu was calculated according to the date of the Ganzhi period. In ancient China, the 10 characters of "a, B, C, D, Wu, Ji, G, Xin, Ren and GUI" were called "Heavenly Stems", while the 12 characters of "ZiChou, Yin, Mao, Chen and Yu Xu, Hai" were called "earthly branches". Ganzhi is the general name of tiangan and dizhi. There are 60 combinations of a word in tiangan and a word in dizhi, which is often called "60 Jiazi". The trunk and branch branches were first used to record the day, and later to record the year, month and time. Poster production: fangjinyang This year's summer solstice is June 21 of the Gregorian calendar. From the summer solstice, the first "gengxu day" is June 26; The second "Gengshen day" is July 6; The third "Geng day" (Geng Wu day) is July 16, so July 16 has become the starting day of the first fall of this year (also known as toufu). The first ambush lasts for 10 days, so this year's first ambush is from July 16 to July 25; The last ambush (also called Sanfu) is the first "Geng day" after the beginning of autumn. The beginning of autumn this year is August 7. The first "gengzi day" found in the future is August 15, which is the first day of the last fall. The last ambush lasts for 10 days. Therefore, the last ambush this year is from August 15 to August 24. The time between the first and last ambushes is moderate, with 10 days in some years and 20 days in some years. This year's medium voltage period is 20 days, from July 26 to August 14. Lin Yuan said that generally speaking, the average temperature of medium voltage is the highest among the "three volts". However, due to various meteorological conditions, the extreme temperature throughout the year may not appear in the medium voltage, or even in the "three volts". However, in any case, the "three volt" is just between the solar terms of light summer and heavy summer. It is indeed a hot season in midsummer. In this season, the "steaming and baking" mode will be launched in many places across the country. The public should do a good job in heatstroke prevention and take measures to spend the time safely. (reporter zhourunjian) (outlook new era)