Fog, cloud of small water droplets that is near ground level and sufficiently dense to reduce horizontal visibility to less than 1,000 metres (3,281 feet). The word fog also may refer to clouds of smoke particles, ice particles, or mixtures of these components.
Advection fog often looks like radiation fog and is also the result of condensation. However, the condensation in this case is caused not by a reduction in surface temperature, but rather by the horizontal movement of warm moist air over a cold surface, such as warm moist air flowing over snow.
Types of Fog: There are several types of fog, including radiation fog, advection fog, evaporation fog, and upslope fog, each formed under different environmental conditions.
Learn about fog in meteorology. Discover the definition, how and why fog forms, the different types, and how it differs from other phenomena.
Fog is a common atmospheric phenomenon, often described as a cloud that forms at ground level. It appears as a dense, opaque layer that can significantly obscure vision.
Clouds and fog both form when water vapor condenses or freezes to form tiny droplets or crystals in the air, but clouds can form at many different altitudes while fog only forms near the ground.
Naturally occurring fog, apart from reducing visibility, can influence the vegetation, air quality, radiation budget, which directly affects temperature and surface-air interaction. Several locations on the planet witness fog events, where some episodes are infrequent while others are widespread.
Advection fog can cover wide areas, and the Golden Gate Bridge in San Francisco Bay is often shrouded in advection fog. Sea fog, a type of advection fog, can occur when warm, wet, air rolls off the land and onto the colder sea, or when a warm weather front hits a cold ocean current.