What day is the twenty-four solar terms?

20 15 12.22 (the twelfth day of the lunar calendar) This day is the winter solstice, starting from the ninth day! China has been in cold weather for several years since the winter of November. Astronomical experts said that "the Ninth Five-Year Plan" is a more applicable solar term in northern China, especially in the middle and lower reaches of the Yellow River. From the day of winter solstice, it entered the "number nine", commonly known as "cross nine", and then every nine days as a unit, called "nine". After nine "nines", it is exactly eighty-one days, that is, "nine out", and then spring blossoms. The widely circulated "99-99 Xiehan Song" from winter solstice, commonly known as "99-99 Song", vividly records the climate and phenological changes between winter solstice and vernal equinox, and also expresses some laws of agricultural activities. The widely circulated song 1929 for removing cold says: "1929 does not shoot, 1949 walks on the ice, 1969 sees the willows, 1979 opens the river, 1999.