Question

How is fog formed?

Answer 1

Hint: Fog in general is water that has evaporated and was previously an invisible gas. This gas is well known to us as water vapor. It usually settles in the air that is close to the ground which produces the fog.

Complete step by step answer:
Fog is a mixture of liquid and gas. In terms of a colloid, fog can be divided into the dispersed phase and the dispersed medium where in the dispersed phase is Liquid and the dispersed medium is Gas. This colloid is also known as an Aerosol. Fog is usually formed in low lying areas that are known to get extremely humid. It consists mostly of water vapor. But this water vapor is not completely gas because if it was, we would not be able to see it. Fog is formed because the water vapor condenses to form small water droplets that continue to stay in the air relatively close to the ground. They are found in regions that are colder and experience air pollution in the form of small dust particles. These water droplets stick to the dust particles. Fog that is usually formed near sea shores or water bodies that may have salt dissolved in it is mostly formed from the fact that these water vapour particles cling onto the salt particles that have been dissolved in the water vapour that was previously water from the sea or the water body. There are different types of fog depending on the types of dust particles or particles in general that it attaches to.

Note: There is a difference between smoke and fog. For smoke, the dispersed phase is solid and the dispersed medium is gas. This colloid is called a solid aerosol. Whereas for fog, we have as mentioned, Dispersed phase is liquid and Dispersed medium is gas. This is called liquid aerosol.