How many meters is the average height of smog?

Smog mainly accumulates in spaces below 50 meters in altitude. Floors above 50 meters are "safe zones" where relatively clean air can be breathed.

Fog is an aerosol system composed of a large number of tiny water droplets or ice crystals suspended in the air near the ground. It mostly appears in autumn and winter (which is also one of the reasons for the widespread haze weather across the country in January 2013). It is the product of water vapor condensation (or sublimation) in the air near the ground. The existence of fog will reduce the transparency of the air and worsen the visibility. If the horizontal visibility of the target object is reduced to less than 1,000 meters, the weather phenomenon of water vapor condensation (or sublimation) suspended in the air near the ground is called fog (Fog) .

Haze (mái), also known as haze (smog), dust, sulfuric acid, nitric acid, organic hydrocarbons and other particles in the air can also make the atmosphere turbid. This phenomenon in which the horizontal visibility of the target object is between 1,000 and 10,000 meters is called light fog or mist.

The atmospheric humidity should be saturated when fog is formed (if there are a large number of condensation nuclei, the relative humidity may not necessarily reach 100% before saturation may occur). Because the light scattered by fog composed of liquid water or ice crystals has little relationship with wavelength, the fog looks milky white or bluish white and gray.

Extended information:

1. Three factors in the formation of haze

The first is the physical source of particulate dust. my country has the largest Loess Plateau area in the world, and its soil texture is most prone to generating granular dust particles.

The second is the dust caused by poor movement. For example, if the mud in the flowerbeds in the middle of the road or on the street curbs flows onto the road after it rains or is splashed with water, it will dry up for an hour and be turned around by the wheels, causing a large amount of dust. Even if these particulate matter falls back to the ground, it will cause dust. Cars kept passing by and were flung over the city again.

The third is that the dust source and movement difference process are concentrated within a certain spatial range, and the particles eventually condense with water molecules to form haze. At present, there are quite abundant stocks of the three elements of haze structure in more than 350 cities in the Loess Plateau region of my country.

2. The height of the "safety zone" is variable

Meteorological experts explained that when the air flow is relatively stable, particulate matter in the air will indeed precipitate and concentrate within a certain height range, but the height does not matter. It is uncertain and depends on the size of particulate matter and the concentration of haze pollution.

When there is wind, particulate matter is not stable in the air. It will move due to the rolling of the airflow, and will not settle at low altitudes. When the air volume is large, the airflow is mixed. In this case, the index of particulate matter is not directly related to the height of the floor. Due to the airflow, the particulate matter may even hover several hundred meters in the air. Therefore, it is not accurate to judge the "safe zone" of smog by height.

Baidu Encyclopedia - Smog

China News - The higher the floor in windless conditions, the lower the PM2.5. There is no rumor that 50 meters is the dividing point