What day is winter?

The winter solstice has the shortest day and the longest night in all parts of the northern hemisphere. The shorter the day, the extreme night phenomenon appears in the Arctic. From winter to the sun, the sun shines directly on the Tropic of Capricorn, and the sun is most inclined to the northern hemisphere, and the solar altitude angle is the smallest. The solstice in winter is the turning point when the direct point of the sun returns to the north. After this day, it went back, and the direct point of the sun began to move northward from the tropic of Capricorn, and the days in the northern hemisphere became longer day by day.

According to the law of solar terms, beginning of spring is the starting point of the rising of "Yin and Yang" qi in Yang Qi. Since the beginning of spring, Yang Qi has changed and Yang Qi has risen. The beginning of spring marks the beginning of a new cycle and the rebirth of everything. The solstice in winter is the starting point for the return of the sun. Since the winter solstice, the height of the sun has risen, and the winter solstice marks a new cycle of direct sunlight movement, which increases day by day during the day. The ancients also regarded the solstice in winter as a "good day".