A picture of how smoke is formed.

Fog is a common weather phenomenon, which is composed of water droplets or ice crystals suspended in the atmosphere near the earth's surface. Fog will affect visibility and traffic. According to the international definition, the visibility in fog is less than 1 km. When the temperature reaches the dew point temperature (or near the dew point temperature), the water vapor in the air condenses to form fog.

Haze is a weather phenomenon in meteorology, also known as haze, which refers to a large number of extremely fine dry dust particles such as dust, sulfuric acid, nitric acid, organic hydrocarbons, etc. floating in the air evenly, which makes the air turbid, blurs the vision and deteriorates the visibility. If the horizontal visibility is less than 65,438+00,000 meters, the visual distance obstacle caused by this non-aqueous aerosol system is called haze or haze, and the Hong Kong Observatory calls it haze.

Difference: The difference between haze and fog is that the relative humidity is not large when haze occurs, but it is saturated in fog (if there are a lot of condensation nuclei, the relative humidity may not reach 100%, which may lead to saturation). Generally, when the relative humidity is less than 80%, the poor visibility caused by blurred vision is caused by smog; When the relative humidity is greater than 90%, the deterioration of visibility caused by blurred vision is caused by fog; When the relative humidity is between 80% and 90%, the deterioration of visibility caused by blurred vision is caused by the mixture of haze and fog, but its main component is haze.

The thickness of haze is relatively thick, which can reach about 1-3 km. The distribution of smog particles is relatively uniform, and the scale of smog particles is relatively small, ranging from 0.00 1 micron to 10 micron, with an average diameter of about 1-2 micron. Floating particles are invisible to the naked eye. Because the smog is composed of dust, sulfuric acid, nitric acid and other particles, the longer the scattering wavelength, the more the light ratio, so the smog looks yellow or orange-gray.

Generally, the thickness of fog is relatively small, and the thickness of common radiation fog is between tens of meters and one hundred and two hundred meters. Fog, like clouds, has obvious boundary with clear sky area, and the droplet concentration distribution is uneven. The droplet size is large, ranging from a few microns to 100 micron, with an average diameter of about 10-20 micron. The naked eye can see the droplets floating in the air. 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.