The reason for fog.

Fog – It is a cloud which is in contact with the ground. Basically, there is no difference between a fog and a cloud above the atmosphere. When a cloud descends to the ground or to the surface of the sea it is called fog.

Fog is usually seen at night and early in the morning, on low, pitched pieces of land or on the water surface. The reason for this is that the cold air current is rubbing against the hotter surface of the land part or water. It is very common especially in the autumn. Because every day in the autumn, the air is cooling faster than the earth or water. After dark patches on steady nights, fog occurs in thin layers near the surface of the soil in low places. By the cooling of the soil at night, the lower part of air becomes cooler. Fog occurs just above the places where the cold air layer joins with moist and warmer air.