The difference between fog and haze

The difference between fog and haze: visibility, relative humidity, thickness, boundary characteristics, color, diurnal variation.

1. Visibility: The horizontal visibility of fog is usually less than 1 km, while the horizontal visibility of haze can be less than 10 km.

2. Relative humidity: The relative humidity of fog is usually greater than 90%, while the relative humidity of haze is less than 80%.

3. Thickness: The thickness of fog is usually around tens of meters to 200 meters, while the thickness of haze can reach about 1-3 kilometers.

4. Boundary characteristics: The boundary characteristics of fog are relatively clear. After the fog area, there may be clear sky. However, there is no obvious boundary between haze and clear sky areas.

5. Color: The color of fog is usually milky white or bluish white, while the color of haze can be yellow or orange-grey.

6. Diurnal variation: Fog generally appears from midnight to early morning, while the diurnal variation characteristics of haze are not obvious. If the air mass does not change significantly and the air mass is relatively stable, it will continue to appear for a longer time.

Components of haze

Haze is composed of dust, sulfuric acid, nitric acid, organic hydrocarbons and other particles in the air. It can also make the atmosphere turbid, blur vision and cause visibility to deteriorate. If the horizontal visibility is less than 10,000 meters, the visual range obstruction caused by this non-aqueous aerosol system is called haze or dust. -haze), the Hong Kong Observatory calls it Haze.

Smog is mainly composed of sulfur dioxide, nitrogen oxides and inhalable particulate matter. The first two are gaseous pollutants, and the last particulate matter is the main cause of aggravating haze weather pollution. They are related to The mist combined to make the sky instantly gloomy and gray. The English abbreviation of particulate matter is PM. What Beijing monitors is fine particulate matter (PM2.5), which is pollutant particles with an aerodynamic equivalent diameter of less than or equal to 2.5 microns.