What Does Fog Mean?

A cloud in contact with the ground is termed a fog. Basically, there is no difference between a fog and a floating cloud, high in the sky. A cloud near to the surface of the sea or the earth is called “fog”.

We see the most common form of fog in the morning, over small bodies of water, lakes, rivers, and over the lowlands. They are caused by the cold currents in the air striking from above, upon the warmer surface of land or water. These are very common in the autumn season. The air starts cooling day by day than the land or the water. On calm and still nights, thin layers of fog form close to the ground in low places. The lower air gets cooler at night, with the cooling of the earth. Fog forms, when this cooler air melts the moist warmer air just above. The city fogs are much thicker than those in the countryside. There are more dust and soot in the cities, it mixes up with water particles to form a thicker blanket of fog.

Damp and warm air passes over the cold water flowing south, from the Arctic circle. The chill of water condenses the air moisture into tiny water drops. These tiny drops remain suspended in the air like fog. These fogs are most thick in the world off the coast of Newfoundland.

The fogs in San Francisco are formed in an opposite way. The cool breeze blows over the warm sand dunes; the overnight moistened sand due to rain forms a thick fog bank due to evaporation. Due to the droplets being smaller these cloud drops give a thicker appearance to the fogs. A large number of small drops absorb more light than a smaller number of large drops, as in the case of clouds, and thus the fogs seem denser.