If the atmospheric visibility near the earth's surface is reduced to 0.62 mi (1 km) or less due to floating water droplets in the air, it is called fog. Fog can form in two ways: either by cooling the air to its dew point (e.g., radiation fog,...

Cloud of small water droplets near ground level that is dense enough to reduce horizontal visibility to less than about 3,000 ft (1,000 m). Fog may also refer to clouds of smoke particles (smog), ice particles, or mixtures of these components. When...

Defined by the International Standards Organization (ISO) as a meteorological condition in which the presence of a suspension of water droplets in the air reduces visibility to less than 1 km. See also:...

A colloidal dispersion of a liquid in air. Smog is an artificial fog produced near the ground by photochemical reactions in polluted atmospheres, see Photochemical oxidants. see...

Fog is a cloud in contact with the ground. Fog differs from other clouds only in that fog touches the surface of the Earth. The same cloud that is not fog on lower ground may be fog where it contacts higher ground such as hilltops or mountain ridges....