What is smog?

Haze is also called atmospheric brown cloud. In the ground meteorological observation standard of China Meteorological Bureau, the definition of haze weather is: "A large number of extremely fine dry dust particles float evenly in the air, which makes the air with horizontal visibility less than 10 km generally turbid, making bright objects in the distance slightly yellow and red, and making darker objects slightly blue." At present, there are four areas with serious smog in some parts of China: Huanghuaihai area, Yangtze River basin, Sichuan basin and Pearl River Delta.

The difference between fog and haze: fog is an aerosol system, which consists of a large number of tiny water droplets or ice crystals suspended in the air near the ground, and the visibility is reduced to below 1 km.

Generally speaking, the difference between fog and haze mainly lies in the size of water content: fog with water content above 90% and haze with water content below 80%. Between 80% and 90%, it is a mixture of fog and haze, but the main component is haze. In terms of visibility, if the horizontal visibility of the target is reduced to less than 1 km, it is fog; The horizontal visibility is between 1 km and1km, which is called light fog or haze; The horizontal visibility is less than 10 km, which is caused by dust particles, that is, haze or ash haze. In addition, there are some visible "differences" between haze and fog: the thickness of fog is only tens of meters to 200 meters, while the tyrant is 1 km to 3 kilometers; The colors of fog are milky white and bluish white, while haze is yellow and orange gray. The boundary of fog is clear, and it may be clear in Wan Li after passing through the "fog area", but the boundary between haze and surrounding environment is not obvious.