In the mild cold season, Subsolar point In the southern hemisphere, the heat in the northern hemisphere is still lost, and the heat absorbed in the day is still less than the heat released at night, so the temperature in the northern hemisphere continues to decline. After the winter solstice, the cold air frequently moves southward, and the temperature continues to decrease. The temperature drops to the lowest during the mild and severe cold of the year. A folk saying goes, "When it's cold, it's at twenty-nine or thirty-nine, and the weather is so cold that it shakes." This shows the cold degree of the Xiaohan solar term.
