How is the foggy weather formed?

The formation of fog is related to the specific weather situation and various meteorological factors, especially the low-level humidity, so the fog on land also appears with the cloud system of the system. Different types of fog have different weather situation and cloud field characteristics in the early and late stages. For example, radiation fog is mostly formed when the rain (cloudy) turns fine, so from the cloud field, the fog is formed where the cloud belt moves; Advection radiation fog is mostly formed in the early stage from sunny to cloudy (rainy). Seen from the cloud field, the fog area is formed in the clear sky area near the east side of the western system cloud system. Advection fog is mostly formed in rainy weather, with high temperature and high air humidity in the early stage. Seen from the cloud field, the fog area is on the south side of the system cloud belt or in the cloud belt.