A report on Fog

View from Blassenstein mountain near Scheibbs (Lower Austria) to the west, with fog over Erlauf valley and Danube
A massive fog bank over Twentynine Palms, California, covers the entire city as it begins to rise and join the clouds above it.
A foggy Aura River in Turku, Finland
Minute droplets of water constitute this after-dark radiation fog, with an ambient temperature of -2 C. Their motion trails are captured as streaks.
A close-up view of water droplets forming fog. Those outside the camera lens's depth of field appear as orbs.
Advection fog layer in San Francisco with the Golden Gate Bridge and skyline in the background
Heavy fog on a road near Baden, Austria
Light fog reduces visibility on a suburban street, rendering the cyclist very hazy at about 200 m. The limit of visibility is about 400 m, which is before the end of the street.
Sutro Tower casts a 3-dimensional fog shadow
Morning freezing fog in Elko, Nevada
Pogonip fog in Virginia City, Nevada, from an early 20th-century postcard
Tree in field during extreme cold with frozen fog
Ice fog on Pyhäjärvi, Tampere during sunset.
Fog rolls into Seattle from the sea
Sea fog or "fret" encroaching on Brighton Pier
Sea fog in the Arctic Ocean near the island of Jan Mayen
Maple tree with red leaves in the morning mist, in western Estonia
A fog on the field of the Leppälahti ja Kuivaniemi villages in Kuopio, Finland
Fog hovering over the valleys surrounding La Silla Observatory.<ref>{{cite web|title=Sunset Panorama at La Silla|url=http://www.eso.org/public/images/potw1544a/|work=eso.org|url-status=live|archive-url=https://web.archive.org/web/20151128073056/http://www.eso.org/public/images/potw1544a/|archive-date=28 November 2015}}</ref>
Fog surrounding skyscrapers in the Melbourne city centre
Light fog over Taipei, Taiwan with Taipei 101 in the background
Fog in London with the Palace of Westminster in the background
Dense fog over Indian subcontinent, captured by NASA's Aqua satellite in December 2012
Fog partially obscuring a mountain in Tirupati in the India summer.

Visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface.

- Fog
View from Blassenstein mountain near Scheibbs (Lower Austria) to the west, with fog over Erlauf valley and Danube

44 related topics with Alpha

Overall

Clouds, formed by condensed water vapor

Water vapor

6 links

Gaseous phase of water.

Gaseous phase of water.

Clouds, formed by condensed water vapor
frameless
Evidence for increasing amounts of stratospheric water vapor over time in Boulder, Colorado.
MODIS/Terra global mean atmospheric water vapor in atm-cm (centimeters of water in an atmospheric column if it condensed)
Cryogeyser erupting on Jupiter's moon Europa (artist concept)
Artist's illustration of the signatures of water in exoplanet atmospheres detectable by instruments such as the Hubble Space Telescope.

Fog and clouds form through condensation around cloud condensation nuclei.

Mean precipitation based on global high resolution climate data (CHELSA)

Precipitation

4 links

Any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds.

Any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds.

Mean precipitation based on global high resolution climate data (CHELSA)
Countries by average annual precipitation
A thunderstorm with heavy precipitation
Late-summer rainstorm in Denmark
Lenticular cloud forming due to mountains over Wyoming
Condensation and coalescence are important parts of the water cycle.
Puddle in the rain
An accumulation of ice pellets
A large hailstone, about 6 cm in diameter
Snowflake viewed in an optical microscope
Convective precipitation
Orographic precipitation
Lake-effect snow bands near the Korean Peninsula in early December 2008
Rainfall distribution by month in Cairns showing the extent of the wet season at that location
Standard rain gauge
Updated Köppen-Geiger climate map
Rainfall estimates for southern Japan and the surrounding region from July 20 to 27, 2009.
Extreme precipitation events have become more common in the U.S. over recent decades.
Image of Atlanta, Georgia, showing temperature distribution, with hot areas appearing white
Example of a five-day rainfall forecast from the Hydrometeorological Prediction Center

Thus, fog and mist are not precipitation but colloids, because the water vapor does not condense sufficiently to precipitate.

400x400px

Cloud

4 links

Aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space.

Aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space.

400x400px
Stratocumuliform cloudscape
Tropospheric cloud classification by altitude of occurrence: Multi-level and vertical genus-types not limited to a single altitude level include nimbostratus, cumulonimbus, and some of the larger cumulus species.
Cumulus humilis clouds in May
Windy evening twilight enhanced by the Sun's angle, can visually mimic a tornado resulting from orographic lift
Nimbostratus cloud producing precipitation
Cirrus fibratus clouds in March
Stratocumulus over Orange County.
Stratocumulus cloud
Cumulus humilis clouds
Cumulonimbus cloud over the Gulf of Mexico in Galveston, Texas
High cirrus upper-left merging into cirrostratus and some cirrocumulus upper right
A large field of cirrocumulus
Sunrise scene giving a shine to an altocumulus stratiformis perlucidus cloud (see also 'species and varieties')
Altostratus translucidus near top of photo merging into altostratus opacus near bottom
Cumulus humilis clouds over Jakarta, Indonesia
Stratocumulus stratiformis perlucidus over Galapagos, Tortuga Bay (see also 'species and varieties')
Stratus nebulosus translucidus
Deep multi-level nimbostratus cloud covering the sky with a scattered layer of low stratus fractus pannus (see also 'species' and 'supplementary features' sections)
Cumulus humilis and cumulus mediocris with stratocumulus stratiformis perlucidus in the foreground (see also 'species and varieties')
Towering vertical cumulus congestus embedded within a layer of cumulus mediocris: Higher layer of stratocumulus stratiformis perlucidus.
Progressive evolution of a single cell thunderstorm
Isolated cumulonimbus cloud over the Mojave Desert, releasing a heavy shower
Altocumulus lenticularis forming over mountains in Wyoming with lower layer of cumulus mediocris and higher layer of cirrus spissatus
Example of a castellanus cloud formation
Cumulus mediocris cloud, about to turn into a cumulus congestus
A layer of stratocumulus stratiformis perlucidus hiding the setting sun with a background layer of stratocumulus cumulogenitus resembling distant mountains.
Cirrus fibratus radiatus over ESO's La Silla Observatory
Altocumulus stratiformis duplicatus at sunrise in the California Mojave Desert, USA (higher layer orange to white; lower layer grey)
Cumulus partly spreading into stratocumulus cumulogenitus over the port of Piraeus in Greece
Cumulonimbus mother cloud dissipating into stratocumulus cumulonimbogenitus at dusk
Cirrus fibratus intortus formed into a Kármán vortex street at evening twilight
Global cloud cover, averaged over the month of October 2009. NASA composite satellite image.
Lenticular nacreous clouds over Antarctica
Noctilucent cloud over Estonia
Joshua Passing the River Jordan with the Ark of the Covenant (1800) by Benjamin West, showing Yahweh leading the Israelites through the desert in the form of a pillar of cloud, as described in
Stratocumulus stratiformis and small castellanus made orange by the sun rising
An occurrence of cloud iridescence with altocumulus volutus and cirrocumulus stratiformis
Sunset reflecting shades of pink onto grey stratocumulus stratiformis translucidus (becoming perlucidus in the background)
Stratocumulus stratiformis perlucidus before sunset. Bangalore, India.
Late-summer rainstorm in Denmark. Nearly black color of base indicates main cloud in foreground probably cumulonimbus.
Particles in the atmosphere and the sun's angle enhance colors of stratocumulus cumulogenitus at evening twilight
Total cloud cover fraction averaged over the years 1981-2010 from the CHELSA-BIOCLIM+ data set

Conductive, radiational, and evaporative cooling require no lifting mechanism and can cause condensation at surface level resulting in the formation of fog.

This graph shows the maximum percentage, by mass, of water vapor that air at sea-level pressure across a range of temperatures can contain. For a lower ambient pressure, a curve has to be drawn above the current curve. A higher ambient pressure yields a curve under the current curve.

Dew point

3 links

Temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content.

Temperature to which air must be cooled to become saturated with water vapor, assuming constant air pressure and water content.

This graph shows the maximum percentage, by mass, of water vapor that air at sea-level pressure across a range of temperatures can contain. For a lower ambient pressure, a curve has to be drawn above the current curve. A higher ambient pressure yields a curve under the current curve.
Graph of the dependence of the dew point upon air temperature for several levels of relative humidity.

In the air, the condensed water is called either fog or a cloud, depending on its altitude when it forms.

Harmattan Haze in Abuja.

Haze

2 links

Traditionally an atmospheric phenomenon in which dust, smoke, and other dry particulates suspended in air obscure visibility and the clarity of the sky.

Traditionally an atmospheric phenomenon in which dust, smoke, and other dry particulates suspended in air obscure visibility and the clarity of the sky.

Harmattan Haze in Abuja.
Haze over the Mojave Desert from a brush fire in Santa Barbara, California, seen as the Sun descends on the 2016 June solstice, allows the Sun to be photographed without a filter.
Bushfire haze in Sydney Australia.
Haze as smoke pollution over the Mojave from fires in the Inland Empire, June, 2016, demonstrates the loss of contrast to the Sun, and the landscape in general.
Haze causing red clouds, due to the scattering of light on smoke particles, also known as Rayleigh scattering during Mexico's forest fire season.
Haze in Monterrey, Mexico during grassland fires.

The World Meteorological Organization manual of codes includes a classification of particulates causing horizontal obscuration into categories of fog, ice fog, steam fog, mist, haze, smoke, volcanic ash, dust, sand, and snow.

Tule fog captured by NASA's Terra Satellite

Tule fog

2 links

Tule fog captured by NASA's Terra Satellite
Tule fog settled on an orchard in Stanislaus County in late December.
Tule fog in Bakersfield

Tule fog is a thick ground fog that settles in the San Joaquin Valley and Sacramento Valley areas of California's Central Valley.

Stratus undulatus clouds during a rainy day.

Stratus cloud

2 links

Stratus clouds are low-level clouds characterized by horizontal layering with a uniform base, as opposed to convective or cumuliform clouds that are formed by rising thermals.

Stratus clouds are low-level clouds characterized by horizontal layering with a uniform base, as opposed to convective or cumuliform clouds that are formed by rising thermals.

Stratus undulatus clouds during a rainy day.
A cirrostratus cloud
Stratocumulus cloud

These clouds are essentially above-ground fog formed either through the lifting of morning fog or through cold air moving at low altitudes over a region.

Paranal Observatory on Cerro Paranal in the Atacama Desert is one of the driest places on Earth.

Humidity

3 links

Concentration of water vapor present in the air.

Concentration of water vapor present in the air.

Paranal Observatory on Cerro Paranal in the Atacama Desert is one of the driest places on Earth.
A hygrothermograph for humidity and temperature recording
Hygrometer for domestic use, wet/dry psychrometer type
Thermo hygrometer displaying temperature and relative humidity
Hygrostat set to 50% relative humidity
Humidor, used to control humidity of cigars
Average humidity around Australia year-round at 9 am
Tillandsia usneoides in Tropical house, Royal Botanic Gardens, Kew. It is growing where the climate is warm enough and has a relatively high average humidity.
Effects of high humidity level in a building structure (primary efflorescence)
Desiccant bag (silica gel), commonly included in packages containing electronic products to control humidity
Global distribution of relative humidity at the surface averaged over the years 1981–2010 from the CHELSA-BIOCLIM+ data set

Humidity indicates the likelihood for precipitation, dew, or fog to be present.

Fog over the Golden Gate Bridge (May 2009)

San Francisco fog

2 links

Common weather phenomenon in the San Francisco Bay Area as well as along the entire coastline of California extending south to the northwest coast of the Baja California Peninsula.

Common weather phenomenon in the San Francisco Bay Area as well as along the entire coastline of California extending south to the northwest coast of the Baja California Peninsula.

Fog over the Golden Gate Bridge (May 2009)
Fog outside the Golden Gate
Fog enters San Francisco Bay through the Golden Gate, seen here in August 2012

The frequency of fog and low-lying stratus clouds is due to a combination of factors particular to the region that are especially prevalent in the summer.

Airplane flying into clouds on descent for landing

Visibility

2 links

Measure of the distance at which an object or light can be clearly discerned.

Measure of the distance at which an object or light can be clearly discerned.

Airplane flying into clouds on descent for landing
Foggy morning road
On clear days, Tel Aviv's skyline is visible from the Carmel mountains, 80 km north

Fog and smoke can reduce visibility to near zero, making driving extremely dangerous.