Where and under what conditions will the fog appear?

Fog will appear in the air, mostly between February and April in spring. ?

Forming conditions: cooling, humidifying and increasing water vapor content. ?

When the relative humidity reaches 100%, the water vapor in the air will condense into fine water droplets suspended in the air under the condition of sufficient water vapor, breeze and stable atmosphere, which will reduce the ground visibility. This weather phenomenon is called fog.

The difference between fog and haze

First, the horizontal visibility is different. The horizontal visibility of fog is less than 1000 m, and that of haze is less than 10 km.

Second, the relative humidity is different. The relative humidity of fog is more than 90%, and that of haze is less than 80%. 80% ~ 90% of relative humidity is a mixture of haze and fog, but its main component is haze.

Third, the thickness is different. The thickness of fog is only about tens of meters to 200 meters, and the thickness of haze can reach 3000 meters.

Fourth, the boundary features are different. The boundary of fog is very clear, and the "fog area" may be clear Wan Li; There is no clear boundary between smog and clear sky.

Fifth, the colors are different. Fog is milky white and bluish white, haze is yellow and orange gray.

Sixth, the formation conditions are different. Although the formation of fog and haze requires a breeze or no wind, the atmospheric state is stable, that is, there must be an inversion layer, but fog needs certain water vapor and cooling conditions to make the air saturated and condense; The formation of smog does not need water vapor and cooling conditions, mainly because the (dry) particles in the air should reach a certain concentration and the relative humidity should not be large.

Seventh, the composition is different. Fog is mainly composed of tiny water droplets or ice crystals, and the size of water droplets is generally 3 ~ 100 micron. Smog is composed of complex tiny particles invisible to the naked eye, and the diameter of smog particles is only 0.3 ~ 0.6 micron.

Eighth, the changes are different every day. Fog usually appears most easily from midnight to early morning, and dissipates quickly after sunrise. The diurnal variation characteristics of haze are not obvious. When the air mass changes little and the atmospheric stratification is stable, it lasts for a long time.

Ninth, seasonal changes are different. Fog may appear all year round in China, with fog in most areas in autumn and winter and less fog in spring and summer. Smog has obvious seasonal changes in most parts of the country, with more in winter and less in summer, and it is in the middle of spring and autumn.

Ten is the indication meaning is different. Generally speaking, fog is indicative of weather forecast, such as the proverb "Ten fogs and nine sunny days"; Haze is an environmental problem, and its guiding significance in air pollution research and air quality prediction is more important.