Cause of cold wave

High pressure cyclone separator. For example, in China, a high-pressure cyclone usually blows near Ulaanbaatar in winter, as opposed to a subtropical sub-low-pressure cyclone. The central air pressure is high and the surrounding air pressure is low, so for the air pressure center, it flows downward, and the air pressure center has plenty of sunshine, low temperature and high air pressure; For the periphery of the air pressure center, there is a horizontal movement of air flow, which flows out from the center, and the high pressure in winter is caused by cold, so the horizontal air flow coming out of the center is colder than other places, which will cause the temperature in other places to drop. Moreover, Mongolia and Siberia have strong high pressure and strong winds, which will cause the temperature in some places to drop sharply. The Mongolian-Siberian high in East Asia is the strongest cold high in the world. Its eastward movement is characterized by large-scale cold air activity, which leads to strong wind cooling in the passing area. Rainy weather is formed where the front of cold air meets warm air, and the main body of cold and high pressure reaches this area to maintain sunny and hot weather. In the Arctic, due to the weak sunlight, the ground and the atmosphere get less heat, and it snows all year round. In winter, the direct sunlight crosses the equator to reach the southern hemisphere, and the cold degree in the Arctic region is stronger and the scope is expanded.

The temperature is generally below minus 40℃-50℃. Large-scale cold air masses gather to a certain extent, and under the action of suitable high-altitude circulation, they will invade southward on a large scale, forming cold wave weather.

Cold wave is a kind of disastrous weather in winter, and people are used to calling it cold wave. The so-called cold wave is a weather process in which cold air from the north invades China on a large scale, resulting in a large-scale sharp cooling and northerly winds. Cold waves generally occur in late autumn, winter and early spring. According to the regulations of China's meteorological department, if the temperature drop caused by cold air intrusion reaches more than 10℃ and the lowest temperature is lower than 5℃ in one day, it is called a cold wave process. It can be seen that not every cold air heading south is called a cold wave.