5,021 articles
Fecal pellet
In oceanography, a fecal pellet is a compacted package of organic waste egested by zooplankton or fish, and a major vehicle of the biological carbon pump.
Feldspar
Feldspar is a group of rock-forming aluminosilicate minerals containing potassium, sodium, or calcium; it makes up about 60 percent of the Earth's crust and is used mainly in glassmaking and ceramics.
Felsic
Felsic, or acid lava, is the geological term for silica-rich igneous rocks and magmas rich in light-colored minerals like feldspar and quartz, typified by granite and rhyolite.
Fengyun-4A
Fengyun-4A (风云四号A星, FY-4A) is a Chinese geostationary meteorological satellite operated by the China Meteorological Administration. Launched in December 2016, it was China's first three-axis-stabilized quantitative remote sensing satellite in geostationary orbit.
Ferralsols
Ferralsols are deeply weathered, strongly leached soils of the humid tropics, defined by a ferralic horizon and corresponding closely to the Oxisols of USDA Soil Taxonomy.
Ferrel cell
The Ferrel cell is the mid-latitude overturning circulation of the atmosphere, sitting between the Hadley and polar cells and producing the prevailing westerlies, first proposed by William Ferrel in 1856.
Ferrihydrite
Ferrihydrite is a widespread, poorly crystalline iron(III) oxyhydroxide nanomineral, named in 1971, that forms rust-colored precipitates in soils, springs, and acid mine drainage, and has been identified on Mars.
Fetch (oceanography)
Fetch, in oceanography, is the area of open water over which wind blows in a roughly constant direction and generates waves, determining wave size alongside wind speed and duration.
Field capacity
Field capacity is the water content retained in soil after saturation, once excess water has drained under gravity; introduced in 1931, it remains standard in irrigation and hydrologic modeling.
Field notebook
A field notebook is a bound, portable record book in which a scientist, most often a field geologist, records observations, measurements, sketches, and interpretations at outcrops, serving as geology's primary scientific record.
Field spectroscopy
Field spectroscopy is the measurement of spectral reflectance of natural surfaces in the field using portable spectroradiometers, chiefly to support calibration and validation of satellite and airborne imagery.
Figure of the Earth
Figure of the Earth, also called the shape of the Earth, is the model geodesy uses for the planet's form: an oblate spheroid plus the geoid.
Filo del Sol
Filo del Sol is a copper-gold-silver deposit in the high Andes on the Argentina-Chile border, described by BHP as the largest greenfield copper discovery in 30 years.
Fine particulate organic matter
Fine particulate organic matter (FPOM) is the organic fraction of particles between 0.45 and 1000 μm in streams and rivers, and a key food for collector invertebrates.
Fingering instability
Fingering instability, also called wetting front instability, is the breakup of a planar wetting front into narrow wetting fingers during infiltration into unsaturated soil, which speeds water and solute movement to groundwater.
Finnish Meteorological Institute
The Finnish Meteorological Institute (Ilmatieteen laitos) is Finland's national meteorological service and research institute under the Ministry of Transport and Communications, tracing its origins to 1838.
Fire Weather Index
The Fire Weather Index (FWI) is a numeric rating of wildfire danger calculated from daily weather observations, introduced across Canada in 1971 and shown on public fire danger signs.
Fire whirl
A fire whirl, also called a fire devil or firenado, is a spinning vortex of hot air and flame rising from a fire, with large whirls having tornado-like intensity.
Firestorm
A firestorm is a fire so intense that it generates its own wind system, sustaining and spreading the flames, sometimes producing its own pyrocumulonimbus cloud, lightning, and tornadoes.
Firn air
Firn air is the atmosphere trapped in the porous layer of compacting snow between fresh snowfall and glacial ice on polar ice sheets, preserving a record of atmospheric composition covering roughly the last century.
First GARP Global Experiment (FGGE)
The First GARP Global Experiment, also called the Global Weather Experiment, was a year-long international program of global atmospheric observation in 1978–1979 involving more than 140 countries.
First Majestic Silver
First Majestic Silver is a publicly traded Canadian silver and gold mining company, founded by Keith Neumeyer in 2002 and headquartered in Vancouver, that operates underground mines in Mexico.
Fission-track thermochronology
Fission-track thermochronology is a dating method using damage trails from spontaneous uranium fission in minerals such as apatite and zircon to reconstruct rocks' low-temperature thermal histories.
Flash flood
A flash flood is a flood of short duration and high peak discharge that rises rapidly, usually within six hours of intense rainfall or a dam failure.
Flash flood warning
A flash flood warning is an official alert that flash flooding is in progress, imminent, or highly likely, issued in the United States by the National Weather Service.
Flat Earth
Flat Earth, also known as the flat Earth theory, is the disproven belief that Earth is a plane rather than a sphere about 12,742 km across.
Flat-slab subduction
Flat-slab subduction is a style of subduction in which an oceanic plate flattens at about 100 km depth and runs nearly horizontally beneath the overriding plate.
Fleet Numerical Meteorology and Oceanography Center
The Fleet Numerical Meteorology and Oceanography Center (FNMOC) is the United States Navy's operational numerical weather prediction center, dual-located in Monterey, California, and Stennis Space Center, Mississippi.
Fleet Survey Team (United States Navy)
The Fleet Survey Team is a deployable U.S. Navy hydrographic unit, commissioned in 2005 under the Naval Oceanographic Office, that surveys littoral waters, ports, and landing beaches.
Flint
Flint is a hard, dark sedimentary rock made of microcrystalline quartz, occurring as nodules in chalk, whose conchoidal fracture gives razor-sharp edges prized for prehistoric tools and fire starting.