What is the reason for the fog?

The reason of fog formation: When the water vapor in the air reaches the maximum, it will produce water vapor saturation. When the water vapor in the air exceeds saturation, the excess water will condense into tiny water droplets, which will be distributed at low altitude to form fog. At this time, there will be fog. Therefore, when the sun comes out during the day, the ground temperature rises, the temperature rises, and the capacity of water vapor in the air increases, and the fog will gradually dissipate.

Fog mostly appears between February and April in spring. Forming conditions: cooling, humidifying and increasing water vapor content. There are radiation fog, advection fog, mixed fog and evaporation fog.

Fog is one of the weather that has the greatest influence on human traffic activities. Poor visibility in foggy days can easily lead to traffic accidents. Among the traffic accidents in expressway, traffic accidents caused by bad weather such as dense fog account for about a quarter of the total, which not only hinders traffic, but also causes great losses to the country and people's lives and property.

Because the fog is uneven, it will cause visual errors, and the driver's judgment of distance and speed is quite different from the actual situation, and the sight distance is shortened, which is easy to collide with the car in front. Especially in expressway, the speed is high. Once a traffic accident happens, it will often cause a chain reaction and eventually lead to serious traffic accidents.