Why is it foggy in summer?

Warm and humid air moves horizontally and passes through the cold ground or water surface, and the water vapor in the air is gradually liquefied by the cold to form fog.

When the water vapor contained in the air reaches the maximum, it reaches saturation. The higher the air temperature, the more water vapor it contains. 1 m3 air, the maximum water vapor capacity is 6.36g at 4℃; When the temperature is 20℃, the maximum water vapor content in 1 m3 air is17.30g.

If the air contains more water vapor than saturated water vapor at a certain temperature, the excess water vapor will condense out. When enough water molecules combine with tiny dust particles in the air, the water molecules themselves will combine with each other and become small water droplets or ice crystals.

Dissipation reason:

First, due to the warming of the underlying surface, water droplets evaporate;

Second, the increase of wind speed will blow the fog away or lift it into clouds; Then turbulent mixing, water vapor upload, heat transfer, and evaporation of droplets near the ground.

The duration of fog is mainly related to the humidity of the local climate: generally speaking, the short fog in arid areas dissipates within 1 hour, while the long fog in humid areas is the most common and lasts for about 6 hours.