What does smog mean? How is the smog formed?

Haze is the combination of fog and haze, and it is the result of interaction between specific climatic conditions and human activities.

The formation of smoke has three elements:

The first is the physical basic source of particulate matter. China has the largest loess plateau in the world, and its soil texture is the easiest to produce granular dust particles.

Second, poor exercise leads to dust. For example, the mud in the garden in the middle of the road and the soil on the roadside stones will flow to the road after raining or splashing water, which will produce a lot of dust after one hour of drying. Even if these particles fall back to the ground, they will be thrown over the city again because of the continuous passing of cars.

Thirdly, the basic source of dust and the process of movement difference gather in a certain spatial range, and particles finally gather with water molecules to form haze. At present, in more than 350 cities in the Loess Plateau of China, the three elements of smog structure are quite rich.

But there is a big difference between fog and haze. The aerosol system composed of dust, sulfuric acid, nitric acid and other particles in the air causes visual impairment, which is called smog. Haze is haze.

Fog is an aerosol system consisting of a large number of tiny water droplets or ice crystals suspended in the air near the ground. It mostly occurs in autumn and winter (which is also one of the reasons for the large-scale haze weather in China in June 20 13), and it is the product of water vapor condensation (or condensation) in the near-surface air.

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. The phenomenon that the horizontal visibility of the target is 1000 ~ 10000 meters is called light fog or haze.

Extended data:

Smog seems mild, but it contains more than 20 kinds of fine particles and toxic substances harmful to human body, including acid, alkali, salt, amine, phenol, etc., as well as dust, pollen, mites, influenza virus, tuberculosis, pneumococcus, etc., and the content is dozens of times that of ordinary atmospheric water droplets. Haze is more harmful to people's health than fog.

Because the diameter of fine powdery floating particles in smog is generally below 0.0 1 micron, they can directly enter bronchi and even lungs through the respiratory system. Therefore, the biggest impact of smog is the human respiratory system, and the diseases caused are mainly concentrated in respiratory diseases, cerebrovascular diseases, nasal inflammation and other diseases.

At the same time, in the haze weather, the air pressure decreases, the inhalable particulate matter in the air suddenly increases, the air mobility is poor, and the diffusion speed of harmful bacteria and viruses to the surrounding area slows down, resulting in an increase in the virus concentration in the air and a high risk of disease transmission.

Baidu encyclopedia-smog