Why is it foggy at night?

1. If the ground heat is lost, the temperature drops and the air is quite humid, then when it cools to a certain extent, part of the water vapor in the air will condense out and become many small water droplets, which will be suspended in the air layer near the ground to form fog.

2. Both it and the cloud are caused by the temperature drop, and the fog can actually be said to be a cloud near the ground. The temperature is higher during the day, so the air can hold more water vapor. But at night, the temperature drops and the capacity of water vapor in the air decreases, so some water vapor condenses into fog.

3. Especially in autumn and winter, due to the long night, Feng Yun appears frequently, and the ground heat dissipation is faster than that in summer, which leads to a sharp drop in the ground temperature, so that the water vapor in the air near the ground can easily reach saturation in the middle of the night, condense into small water droplets and form fog.

There are three definitions of fog:

1. When the visibility in the atmosphere is lower than 1 km due to the condensation of suspended water vapor, meteorology calls this weather phenomenon fog.

2. Fog is a cloud near the ground.

3. Fog is an aerosol composed of tiny droplets suspended in the atmosphere (described in environmental monitoring). When the water vapor contained in the air reaches the maximum, it reaches saturation. The higher the temperature, the more water vapor is contained in the air. 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. Water vapor in the air exceeds saturation and condenses into water droplets.