Mass fog law

Fog is easy to appear in winter, usually at night when the temperature difference between day and night is large and there is no wind, or from 6 am to 8 am.

Mass fog generally appears in low-lying areas with high air humidity, which is closely related to the local microclimate environment. Most of them are mountain expressways after rain, provided that there is a large temperature difference between day and night and there is no wind.

Due to the mismatch with the large-scale atmospheric environment, mass fog can not only appear frequently in foggy weather (fog with low visibility appears in the local range of tens to hundreds of meters), but also may appear in remote mountainous areas or rural areas with good weather conditions.

According to statistics, fog is more likely to appear on expressways. This is because the fog is very close to the local microclimate environment. Yancheng is located on the coast of the Yellow Sea. When the east wind prevails, a large amount of water vapor blows from the sea, which makes the air humidity relatively high. The temperature difference between day and night on the expressway is larger than that in the urban area. Direct sunlight produces high temperature during the day, and the temperature drops sharply at night, especially in the early morning, when the temperature is close to the "dew point" temperature, it is more likely to produce fog.

In places close to large water bodies, such as Shijiu Lake, Chaohu Lake, Roman Lake and other surrounding areas, "fog" is more common.