Where did the fog come from?

Definition of fog: A large number of water droplets or ice crystal particles suspended in the ground air are attached to it, which makes the horizontal visibility distance fall below 1 km, and it is called "light fog" when the visibility distance is between 1 ~ 5km. Generally, the thickness is tens to hundreds of meters, and the thickness can reach more than 1 km. The fog with a thickness of less than two meters is called shallow fog.

The main factors affecting fog visibility are the concentration and size of fog droplets. Classification of fog: ① According to the different formation processes, fog can be divided into radiation fog, advection fog fog, uphill fog and evaporation fog. ② According to the state of matter, it can be divided into three types: water fog, ice fog and water-ice mixed fog, which are composed of water droplets and ice respectively.

Crystals, water droplets and ice crystals. ③ The synoptic classification of fog divides fog into air mass fog and frontal fog. In addition, people usually call the fog that occurs at sea "sea fog". Clouds are made up of a lot of tiny water droplets or ice crystals. Visible polymers suspended in the atmosphere are usually called fog. Because the atmospheric pressure decreases with the increase of height, the air will expand and cool down when it rises, and the saturated water pressure will also decrease.