What is smog? What is the difference between smog and smog? Brief introduction of smog.

Haze is a combination of fog and haze. 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 (PM 2.5). 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. The difference between smoke and fog is as follows:

1, with different components, fog is composed of water droplets; Haze consists of dust particles, smoke particles or salt particles;

2. The relative humidity is different. Fog is a phenomenon of water vapor condensation, which requires high relative humidity, generally above 90%. Haze is a collection of dust particles, smoke particles or salt particles, and the relative humidity of the air is mostly below 80% when it is formed.

3. The maintenance time is different. Fog is local and short-lived. The concentration changes rapidly when it is formed, and the visibility in all directions is uneven. Fog mostly appears at night to the next morning, and generally weakens and dissipates after noon, with obvious daily changes. Haze has a gradual formation process, which can last for several days and has the characteristics of wide range and uniform visibility in all directions.

4. The vertical height is different. Fog appears in the near-surface layer, its vertical thickness is only a few hundred meters, and the height of haze can reach 1km, or even 3km, and its extension height is relatively high;

5. Different health effects. Fog is a tiny water drop suspended in the air, which has little effect on health; However, most of the dust in smog can be inhaled by human respiratory tract, which affects health;

6. The particle size is different. The droplet size is 100- 102μm, which can be seen by naked eyes. The particle size of smog is 10-3- 10μm, which is invisible to naked eyes.

7. Different colors. Fog is mostly milky white, while haze usually looks yellow or gray because it scatters more visible light with longer wavelengths.