What does the number from summer to night mean? Calculation method of three volts

Although the ancestors in ancient times did not have advanced high-tech technology to calculate time and predict the weather, they summed up their experiences found in long-term agricultural labor, revealed the laws of climate change for people, and summarized them into short proverbs and poems for daily use and dissemination.

March 9 is cold and hot.

A year's climate change is integrated into a short poem. The sentence "The third watch falls in summer" is a summary of climate change, which means that the summer solar term has arrived, but it is not the hottest time of the year. After the summer solar term, the third "Geng Day" began to come to an end, which is the hottest time of the year. As the saying goes, "it's cold in three or nine days, but it's hot in the dog", which is the truth. After the summer solstice, the daytime time in the northern hemisphere gradually decreases. At the same time, after the arrival of the summer solstice, the stars in the night sky gradually become Xia Xing.

10 is a Geng.

To understand the so-called three Geng in this sentence, we must first understand what Geng is, and one Geng is a specific ten days. "Three Geng" is the "third Geng Day" mentioned in the ancient chronology of cadres and branches. The ancients used the combination of 18 days and 12 days to record time, in which the word "Geng" in "Three Geng" is the number "A" in the heavenly stems.

The intermediate delay is not fixed.

How many days is a volt? You need to reason and calculate according to the year and date. In fact, starting from the summer solstice, the third day when the sky is "Geng" is called the first volt, the fourth volt after 10, and the last volt after beginning of autumn. Initial and final fixation is 10 days; Lodging time is not fixed, some years are 10 days, others are 20 days, which is mainly determined by the number of Geng days from summer to Sunday to beginning of autumn: there are 4 Geng days, the interval from lodging to final lodging is 10 days, and there are 5 Geng days, the interval is 20 days.