What is the main difference between fog and smog?

The main differences between fog and smog are: different visibility, different relative humidity, different boundary characteristics and different colors.

1, visibility is different. When the horizontal visibility of the target is reduced to 1000 m, it is fog, and when it is lower than 10000 m, it is haze caused by dust particles.

2. The relative humidity is different. The relative humidity of fog is more than 90%, while that of haze is less than 80%.

3. The boundary features are different. The boundary of fog is very clear. The "fog area" may be the clear sky in Wan Li, but there is no obvious boundary between haze and clear sky.

4. Different colors. Fog is milky white and blue white, while haze is yellow and orange gray. In short, we can make such judgments in our daily life. If the sky has the feeling of flashing, it is fog; If it is dark all the way, it is smog.

Causes of haze weather:

In recent years, smog weather has frequently appeared in many areas of China, especially in the Yangtze River Delta, Beijing-Tianjin-Hebei, Pearl River Delta and other areas, and smog weather has almost become the norm. For the source and composition of smog, most studies believe that it mainly comes from fossil fuels, but the specific research data are quite different. Greenpeace data show that 49% of PM2.5 comes from coal burning, and 16% comes from motor vehicle fuel.

Research by the State Key Laboratory of Environmental Simulation and Pollution Control in Peking University shows that among the sources of PM2.5, the combustion of fossil fuels (including coal and gasoline) accounts for 60% ~ 70%, and others include industrial and building dust and residential fuels.