What is the reason for the haze weather?

First, sulfur dioxide, nitrogen oxides and inhalable particles are the main components of smog, while the first two are gaseous pollutants. Finally,

A particulate matter is the chief culprit that aggravates smog weather pollution. They combine with fog and instantly turn the sky gray. The abbreviation of particulate matter is PM, and what Beijing monitors is fine particulate matter (PM2.5), that is, pollutant particles with a diameter less than or equal to 2.5 microns. This particle itself is not only a pollutant, but also a carrier of toxic substances such as heavy metals and polycyclic aromatic hydrocarbons.

Second, the sources of toxic particulate matter in cities: First, automobile exhaust. Cars that use diesel are "habitual criminals" who emit particles. Small cars that use gasoline emit gaseous pollutants, such as nitrogen oxides, which are easily converted into secondary particulate pollutants in foggy days, aggravating smog.

Industrial waste gas is also a major factor. In 20 12, China burned 3.6 billion tons of standard coal, accounting for 5 1%, and the exhaust gas discharged can be imagined. { 1}

The third is the waste gas emitted by industrial production. For example, industrial kilns and boilers in metallurgy and electromechanical manufacturing industries, as well as a large amount of waste gas generated by the combustion of automobile repair and painting and building materials production kilns.

The fourth is the dust generated by construction sites and road traffic. (fog)

Hazy weather pictures (5 photos)

Fog is an aerosol system composed of a large number of tiny water droplets or ice crystals suspended in the air near the ground, which often appears in autumn and winter (which is also one of the reasons for the large-scale haze weather in China in June 20 13), and is the product of water vapor condensation (or condensation) in the air near the ground. The existence of fog will reduce air transparency and worsen visibility. If the horizontal visibility of the target drops below 1000 meters, the weather phenomenon of water vapor condensation (or condensation) suspended in the air near the ground is called fog. The phenomenon that the horizontal visibility of the target is 1000- 10000 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, the relative humidity may not reach 100%, and saturation may occur). Because the light scattered by fog composed of liquid water or ice crystals has little to do with wavelength, the fog looks milky white or bluish white. (haze)

Haze picture

Haze is composed of particles such as dust, sulfuric acid, nitric acid and organic hydrocarbons in the air. It will also make the atmosphere turbid, blur the vision and worsen the visibility. If the horizontal visibility is less than 65,438+00,000 meters, the sight distance obstacle caused by this non-aqueous aerosol system is called haze or dust haze, and the Hong Kong Observatory calls it haze.