How is cold air formed?

Cold air is formed in extremely cold areas where there is no sunshine.

The high temperature in low latitudes makes the atmosphere expand and thin, which will lead to some heat loss in the atmosphere. At the same time, due to the influence of the earth's rotation and plate movement, various landforms and climatic zones will be formed on the surface.

In some areas, after the surface temperature drops, the air will gradually cool and contract, forming a high pressure area. In other areas, due to the movement of airflow, the air will become dry and lack of temperature, forming a low-pressure area. Then the formation of high pressure area and low pressure area is the embryonic form of cold air. Cold air is cold because it loses a lot of heat energy.

However, this is only the beginning. With the radiation energy of the atmosphere, the air around the high-pressure area will continue to flow to the low-pressure area, forming a large-scale circulation, which is called atmospheric circulation in meteorology. This cycle affects the global climate change. In addition to the influence of the earth's rotation and solar radiation, the distribution of the earth's magnetic field, oceans and continents will also have an impact on the formation of cold air.

For example, the earth's magnetic field will affect the activity of the solar wind, which is the flow of charged particles and will interact with atoms in the atmosphere, affecting the ionization and temperature of the atmosphere. At the same time, the distribution of oceans and continents will also affect the flow and temperature of the atmosphere.

The path of cold air entering China

1. The cold air from Northwest Road (Middle Road) reaches south near China Hetao from key areas and reaches the middle and lower reaches of the Yangtze River and the south of the Yangtze River. The cold air coming down this route, the cold wave weather north of the Yangtze River is mainly northerly wind and cooling. After reaching the south of the Yangtze River, it may develop with rain and snow due to the active fluctuation of the south branch.

2. The cold air on the East Road passes through Mongolia from key areas to the northern part of North China. While the main cold air continues to move eastward, the low-altitude cold air turns to the southwest, invades North China through the Bohai Sea, and then reaches the two lake basins from the lower reaches of the Yellow River. The cold air coming down this route often causes strong winds in the northeast of the Bohai Sea, the Yellow Sea, the lower reaches of the Yellow River and the lower reaches of the Yangtze River, backflow in North China and East China, low temperature and even rainy and snowy weather.

3. The cold air on the west road goes south from key areas and passes through Xinjiang, Qinghai and the northeast of Qinghai-Tibet Plateau, which has a great influence on the northwest, southwest and south of China, but the cooling rate is not great. However, when the fluctuation of the south branch and the fluctuation of the north branch overlap, it can also cause obvious cooling.

4. The cold air of Jiaxi Road on East Road goes south from the lower reaches of Hetao, and the cold air of West Road goes south from the southeast of Qinghai. Two cold air often meet on the east side of the Loess Plateau, between the Yellow River and the Yangtze River, causing a wide range of rain and snow, and then the two cold air meet south, causing strong winds and obvious cooling.

Baidu encyclopedia-cold air