Why does the winter solstice fall on December 22nd every year?

The winter solstice is not fixed on a specific day. Most of the time it is December 22nd every year.

First of all, there is a slight mistake in the question itself. The winter solstice is around December 22nd every year, and it must be December 22nd. The Winter Solstice is a "living festival" like Qingming Festival and is not fixed on a specific day. In some years, the Winter Solstice is December 21 (such as 2016).

The "solstice" in the winter solstice can be understood as "the most" or "the most". On the winter solstice, the sun reaches 270 degrees longitude. my country, which is in the northern hemisphere, has the shortest day, the longest night, the longest shadow, and the least sunlight (about 50% less than the southern hemisphere). From this day until the summer solstice, the days in our country will become longer and longer, and the nights will gradually become shorter.

Climate characteristics of the winter solstice

The temperature drops sharply. The winter solstice usually occurs around December 21. At this time, the northern hemisphere is farthest from the sun and receives less sunlight, so the temperature begins to drop sharply. And because the soil begins to freeze, solar radiation cannot be absorbed smoothly by the soil, which also leads to the arrival of cold weather. Therefore, the winter solstice is the period of the year with the lowest temperatures and the deepest coldness.

Dry and little rain. The climate characteristics of the winter solstice are also reflected in atmospheric circulation and precipitation. Cyclone activity is frequent in winter, and sometimes cold air controls the situation. These factors result in low relative humidity and low precipitation in most areas during the winter solstice, so winter is also a period of high incidence of drought in most areas. Especially in winter in northern areas, the relatively dry air is more obvious due to the influence of cold waves and high pressure.

The wind is strong and the sky is sunny. Another notable climatic characteristic of the Winter Solstice is that the weather is sunny and the wind is strong. In winter, under the influence of a high-pressure system, cold currents instantly intensify and generate cold high-pressure fronts, triggering strong winds. In addition, there is "Ao" wind in Beijing and other places, also known as Aobao breeze, which is a specialty of the northern region and often appears on the days of the winter solstice.