When do fog and mist arise?

It is tiny water droplets condensing from moist air that cause fog and mist to rise. The water droplets can occur at ground level. The air can only hold a limited amount of water. If the air suddenly cools, its capacity to hold water is reduced, which results in a mist or fog.

When fog develops, visibility can be affected quite badly. Mist is less dense. It often occurs on calm, clear nights when heat rises, forming a thin layer of mist close to the ground. Mist often forms over water because a mass of warm air passes over a cold stretch of water.

Sometimes visibility is affected in built up areas due to mist and fog, but this is sometimes mistaken for smog. Smog is a buildup of exhaust fumes and factory smoke which hangs over the area until a huge amount of air movement can blow the smog away.

Fact File:

Fog particles are small, less than 1/25,000 of an inch in diameter. When you have a dense fog and can’t see in front of you, it is because there may be as many as 20,000 of these particles in one cubic inch.

 

Picture Credit : Google