fog

fog
Name	Fog
Formation	Condensation of water vapor near Earth's surface
Causes	Cooling, mixing, advection, evaporation
Typical pressure	Surface-level
Typical temperature	Near dew point

fog Fog is a meteorological phenomenon consisting of suspended liquid water droplets near Earth's surface that reduce visibility. It occurs in diverse regions from coastal zones to urban centers and influences aviation, maritime navigation, and road transport worldwide. Scientists study its microphysics, climatology, and societal impacts across institutions and research programs.

Definition and Classification

Fog is defined by meteorological agencies such as the World Meteorological Organization, the National Weather Service, and the Met Office as a visibility-reducing cloud at surface level. Classification systems developed by the International Civil Aviation Organization and the National Oceanic and Atmospheric Administration distinguish fog from mist and haze based on visibility thresholds established in standards like the International Telecommunication Union's meteorological guidelines. Operational manuals from the Federal Aviation Administration and the European Organisation for the Safety of Air Navigation use these classifications in aeronautical meteorology.

Formation and Meteorology

Formation mechanisms are analyzed using theories from researchers at institutions such as Massachusetts Institute of Technology, Scripps Institution of Oceanography, and the National Center for Atmospheric Research. Radiative cooling scenarios have been modeled in studies linked to NOAA ESRL projects and field campaigns like the ARM Climate Research Facility experiments. Advection fog dynamics are examined using models from the European Centre for Medium-Range Weather Forecasts and the Met Éireann operational suites, while evaporation fog processes are investigated in hydrology programs at University of California, Berkeley and University of Washington.

Types of Fog

Types include radiation fog, advection fog, evaporation (steam) fog, upslope fog, frontal fog, and freezing fog—each described in texts from the American Meteorological Society and case studies from the UK Met Office. Coastal advection events studied near San Francisco Bay and English Channel sites contrast with radiation fog documented in the Great Plains and Siberian Plain. Freezing fog occurrences have been reported in research around Scandinavia and the Canadian Arctic.

Impacts on Transportation and Safety

Fog's effect on transport is central to aviation guidance from the International Civil Aviation Organization and the Federal Aviation Administration, which cite incidents in the historical record such as disruptions at Heathrow Airport and John F. Kennedy International Airport. Maritime navigation procedures from the International Maritime Organization address coastal fog risks documented in studies of the North Sea and Strait of Gibraltar. Road safety interventions informed by research at the Transport Research Laboratory and policy from the European Commission aim to reduce collisions on corridors like the M1 motorway and the Trans-Canada Highway.

Ecological and Environmental Effects

Fog deposition influences ecosystems studied by ecologists at the University of California, Santa Cruz and conservationists working with NatureServe and the Sierra Club. Fog drip supports cloud forest habitats in regions including the California Channel Islands, the Monteverde Cloud Forest in Costa Rica, and the Congo Basin margins. Air quality interactions with fog have been evaluated by researchers affiliated with Environmental Protection Agency programs and studies near urban centers such as Los Angeles, Tokyo, and Beijing.

Measurement and Forecasting

Observation networks by the World Meteorological Organization and national services deploy ceilometers, visibility sensors, and radiosondes in coordination with research from the National Aeronautics and Space Administration and the European Space Agency. Forecasting employs numerical weather prediction systems from the European Centre for Medium-Range Weather Forecasts and ensemble techniques developed at the Met Office and NOAA's Global Forecast System. Field campaigns like the PILPS project and instrument platforms from NCAR advance understanding of microphysical processes.

Cultural and Historical Significance

Fog features prominently in literature, art, and history with depictions by authors and artists associated with movements around Victorian era London and maritime narratives of the Age of Sail. Works by writers linked to Charles Dickens, painters related to the Hudson River School, and poets connected to Romanticism evoke fog in portrayals of urban life and seafaring. Historical events, including naval engagements near the English Channel and strategic movements during the Napoleonic Wars, were affected by low-visibility conditions noted in archives of the Royal Navy and chronicled by historians at institutions like the British Museum.

Category:Atmospheric phenomena