In the 24 solar term songs, winter snow refers to the beginning of winter and light snow, and snow winter refers to heavy snow and winter solstice.
The spring rain shocks the spring, clears the valley, and makes the sky full of awns and summer heat. There is dew in autumn, cold frost in autumn, and snow in winter and slight cold in winter. In the first half of the year it was 621, and in the second half it was 823. The dates of the two festivals are fixed every month, with no difference of one or two days at most.
The twenty-four solar terms originated from the Yellow River Basin. As far back as the Spring and Autumn Period, the four solar terms of mid-spring, mid-summer, mid-autumn and mid-winter were established. After continuous improvement and perfection, by the Qin and Han Dynasties, the twenty-four solar terms had been fully established.
In 104 BC, the "Taichu Calendar" formulated by Deng Pingping formally included the twenty-four solar terms in the calendar and clarified the astronomical position of the twenty-four solar terms.
The time it takes for the sun to travel 15 degrees along the celestial longitude from zero degrees along the celestial longitude is called "a solar term." It runs 360 degrees every year and experiences 24 solar terms, 2 per month.
Among them, the first solar term of each month is the "solar term", which is the 12 solar terms: Beginning of Spring, Jingzhe, Qingming, Beginning of Summer, Mangzhong, Slight Heat, Beginning of Autumn, White Dew, Cold Dew, Beginning of Winter, Heavy Snow and Lesser Cold.
The second solar term of each month is "Zhong Qi", which is the 12 solar terms: rain, vernal equinox, Guyu, Xiaoman, summer solstice, great heat, end of heat, autumnal equinox, frost, light snow, winter solstice and great cold.
The solar terms and the middle qi appear alternately, each lasting 15 days. Nowadays, people have collectively referred to "solar terms" and "zhong qi" as "solar terms".
The twenty-four solar terms reflect the annual apparent movement of the sun, so the dates of the solar terms in the current Gregorian calendar are basically fixed. They fall on the 6th and 21st in the first half of the year, and on the 8th and 23rd in the second half of the year. 1 to 2 days difference.