Inversion noun explanation

Inversion: Under normal circumstances, the atmospheric temperature decreases with the increase of altitude, but under some weather conditions, the atmospheric structure above the ground will have an abnormal phenomenon that the temperature increases with the increase of altitude. The atmosphere where inversion occurs is called "inversion layer".

I. Causes and types of inversion:

1, radiation inversion. On a clear and windless night, the ground radiation is strong, and the near-surface atmosphere cools rapidly, while the upper atmosphere cools slowly, resulting in the inversion phenomenon of upper warming and lower cooling, which is the strongest before dawn and disappears from bottom to top after sunrise. Summer is weak and winter is strong. The inversion in winter in China is mainly this inversion.

2. Advection inversion and frontal inversion. Warm air moves horizontally to the cold ground or water surface. Because the warm air in the lower layer is affected by the cold of the ground or water surface, the temperature drops rapidly, and the upper layer is less affected, thus forming an inversion. Mainly in the mid-latitude coastal areas. Front inversion means that the temperature difference between warm air and cold air is significant near the front, because warm air is above and cold air is below.

3. Terrain inversion. In mountain basins or valleys, at night, due to the rapid heat dissipation on the hillside, the cold air sinks along the hillside, which causes the originally warm air at the bottom of the basin or valley to be pushed up by the cold air, forming a vertical structure of air with warm top and cold bottom, resulting in inversion.

Second, the impact of inversion: foggy and sunny. The foggy weather in the morning is closely related to inversion, which reduces visibility, brings inconvenience to people's travel and even causes traffic accidents. Aggravate air pollution. Due to the existence of inversion, the vertical convection of air is blocked, which will cause the pollutants near the ground not to spread in time, thus endangering human health.