How is haze formed

We all know that the air quality has become worse and worse. Whether it is a first-tier industrial city or a second-tier city, it is particularly prone to smog weather. When traveling in smog weather, not only are the harmful particles in the air larger, which can easily cause some diseases, but the air visibility also becomes relatively low. Therefore, smog is a particularly harmful phenomenon for life. So how is smog formed?

1. Haze is a combination of fog and haze. Smog is common in cities. Many areas in China include fog and haze in warnings and forecasts as disastrous weather phenomena, collectively referred to as "haze weather." Haze is the result of the interaction between specific climate conditions and human activities. The economic and social activities of a high-density population will inevitably emit a large amount of fine particulate matter (PM 2.5). Once the emission exceeds the atmospheric circulation capacity and carrying capacity, the concentration of fine particulate matter will continue to accumulate. At this time, if affected by calm and stable weather, large-scale smog is likely to occur.

2. Haze, as the name suggests, is fog and haze. 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 that causes visual impairment is called haze. Haze is gray haze (smoky clouds).

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 often appears in autumn and winter (this was also one of the reasons for the widespread smog weather across the country in January 2013) and is the product of condensation (or sublimation) of water vapor in the air near the ground. The presence of fog will reduce air transparency and worsen visibility. If the horizontal visibility of the target object is reduced to less than 1,000 meters, the weather phenomenon of condensation (or sublimation) of water vapor suspended in the air near the ground is called fog.

Haze (mái), also known as gray haze (smog), is a particle of dust, sulfuric acid, nitric acid, organic hydrocarbons, etc. in the air that can also make the atmosphere turbid. The phenomenon in which the horizontal visibility of the target object is between 1000 and 10,000 meters is called light fog or mist. When fog is formed, the atmospheric humidity should be saturated (if there are a large number of condensation nuclei, saturation may occur even if the relative humidity does not necessarily reach 100%). Because fog, which is composed of liquid water or ice crystals, scatters light that has little to do with wavelength, the fog appears milky white or bluish white and gray.

Haze weather is a state of air pollution. Haze is a general term for the excessive content of various suspended particulate matter in the atmosphere, especially PM2.5 (particles with an aerodynamic equivalent diameter of less than or equal to 2.5 microns), which is considered to be the "culprit" causing haze weather. As the air quality deteriorates, haze weather phenomena increase in number and the harm becomes more serious. Many areas in China incorporate haze weather phenomena into fog as part of disastrous weather warnings and forecasts. Collectively referred to as "smog weather".