What do you know about smog?

Haze, as its name implies, is fog and haze. Fog is an aerosol system composed of a large number of tiny water droplets or ice crystals suspended in the air near the ground, and it is the product of condensation (or sublimation) of water vapor in the air near the ground. Haze is also called haze (smoke), and particles such as dust, sulfuric acid, nitric acid and organic hydrocarbons in the air can also make the atmosphere turbid. Haze weather is a state of air pollution. Haze is a general term for the excessive content of suspended particulate matter in the atmosphere, especially PM2.5, which is considered to be the "culprit" causing haze weather. Haze warning signals are divided into three levels, which are represented by yellow, orange and red respectively, corresponding to moderate haze, severe haze and severe haze in the forecast level.

Haze is a combination of fog and haze. Smog is very common in cities. In many areas of China, fog and haze are combined as disastrous weather phenomena for early warning and forecasting, which are collectively called "haze weather". Haze is the result of interaction between specific climatic conditions and human activities. The economic and social activities of high-density population will inevitably emit a large number of fine particles (PM2.5). Once the emission exceeds the atmospheric circulation capacity and carrying capacity, the concentration of fine particles will continue to accumulate. At this time, if it is affected by calm weather, it is easy to have a wide range of smog.