What's the difference between fog and haze?

Every time I get up early, I see it's gray outside. Is there a feeling that you can't tell whether it is fog or haze? I believe many people are stupid and confused. Although visually similar, their effects on the body are quite different. If you encounter foggy weather, try to reduce outdoor sports as much as possible, which is more beneficial to your health. So how do you distinguish the two?

Fog and haze weather

First, distinguish between fog and haze.

1. Fog is a natural phenomenon and a visible aggregate of a large number of tiny water droplets (or ice crystals) suspended in the atmosphere near the ground. Fog mostly appears in autumn and winter, which is the product of water vapor condensation (or condensation) in the air near the ground. The existence of fog will reduce air transparency and visibility.

2. Haze, also known as haze, is mainly caused by human factors. It is caused by dust, sulfuric acid, nitric acid, organic hydrocarbons and other particulate matter in the air, which makes the atmosphere turbid, blurs the vision and deteriorates the visibility. If the horizontal visibility is less than 10000 meters, the visual distance obstacle caused by this non-aqueous aerosol system is called haze or haze.

Fog and haze weather

2. What's the difference between fog and haze?

1, with different components, fog is composed of water droplets; Haze consists of dust, smoke 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 large-scale and uniform visibility in all directions.

Fog and haze weather

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

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.