Why is the winter solstice called the winter solstice among the 24 solar terms?

As far as solar terms are concerned, the winter solstice is neither the beginning nor the end of winter, but the beginning of the coldest period of the year. ?

According to modern astronomical science, during the winter solstice, the sun moves to 270 (winter solstice), and the position where the sun directly hits the ground reaches the southernmost point of the year. The sun shines almost directly on the tropic of Capricorn (also known as the winter solstice daily line), and the sun is most biased towards the northern hemisphere. Therefore, the winter solstice is the shortest day in all parts of the northern hemisphere in a year, and the farther north, the shorter the day.

For all parts of the northern hemisphere, the winter solstice is also the day with the lowest sun height at noon all year round. North of the Arctic Circle, the sun is below the horizon all day, which is the widest day of the year in the northern hemisphere. In winter solstice, the northern hemisphere gets the least solar radiation, which is about 50% less than that in the southern hemisphere in hot summer.

Extended data:

The southernmost day of the year. After this day, the direct point of the sun began to move northward from the tropic of Capricorn, and the length of the day in the northern hemisphere began to increase gradually, and the height of the sun also increased gradually at noon.

It is worth noting that around the winter solstice, the earth is located near the perihelion, and its movement speed is slightly faster, which leads to that the time of the sun in the southern hemisphere is about 8 days shorter than that in the northern hemisphere, so the winter in the northern hemisphere is slightly shorter than that in summer.

Note: The polar axis passes through the center of the earth and connects the north and south poles, making an angle of 66 34 ′ with the orbital plane of the earth revolution and perpendicular to the equatorial plane.