Fog

A cloud with its base at the earth's surface. It reduces visibility to below 1 kilometer.

Fog A hydrometeor consisting of a visible aggregate of minute water droplets (or ice crystals), suspended in the atmosphere near the Earth's surface. According to international definition, fog reduces visibility below one kilometer. Fog differs from cloud only in that the base of fog is at the Earth's surface while clouds are above the surface. When composed of ice crystals, it is termed ice fog.

Fine particles of liquid suspended in the air, such as of water in a fog chamber used for acclimatizing recent ex vitro transplants. See: mist propagation.

(abbrev. F) Fog is water droplets suspended in the air at the Earth's surface. Fog is often hazardous when the visibility is reduced to ¼ mile or less.

Fiber-Optic Gyroscope.