What does Tuanwu mean?

Close fog refers to a small area of ??dense fog.

A cloud of fog is essentially a fog, which is a small-scale dense fog formed by the influence of the microclimate environment in a local area. The fog covers a small area (generally one to five kilometers), which is why sometimes the sun is already shining high and the highway is closed due to fog, that is, the "fog" has not dissipated on some sections of the road; the visibility outside the "fog" is good, It is hazy to look around in the fog; its appearance time is usually at night or between 6 and 8 in the morning; highways mostly occur in suburban rural areas, highway bridge sections, mountainous areas after rain, and other areas with large temperature differences.

Foot is often called the "invisible killer" of traffic safety. When fog occurs, the visibility of the air will become lower, and the driver's sight distance will be significantly shortened. The road area will also be greatly reduced.

Causes of formation of fog:

1. Cluster fog is formed due to the radiation cooling of the ground, which cools the air close to the ground and reduces the saturated specific humidity, causing water vapor to condense. The formation of mass fog requires two main conditions. First, there is abundant water vapor in the lower levels and high air humidity. Second, the temperature difference between day and night is large and the wind is light. When the weather is fine, fog is less likely to occur.

2. Compared with urban areas, fog is more likely to occur in suburban and rural areas. Some relatively empty highway sections are also fog-prone areas. Cluster fog is closely related to the local microclimate environment, and the highway road surface has a higher temperature during the day and a larger temperature difference between day and night, which is more conducive to the formation of cluster fog.

3. The increase in some pollutant particles emitted near the highway, such as straw burning in autumn, industrial dust pollution, automobile exhaust emissions, etc. The increase in tiny particles in the air is conducive to the formation of fog.

Reference for the above content: Baidu Encyclopedia-Tuanwu