5,021 articles
Float (oceanography)
In oceanography, a float is an autonomous free-drifting instrument that sinks to a set depth and profiles temperature and salinity, transmitting data by satellite when it surfaces; about 4,000 are operated by the international Argo program.
Floating island
A floating island is a buoyant mass of vegetation, peat, or other material resting on a lake's surface, occurring naturally in wetlands and built deliberately for water treatment.
Flood
A flood is an excess of water on normally dry land, caused by overflowing rivers, heavy rain, snowmelt, or dam failure, and is the most common weather-related disaster.
Flood basalt
A flood basalt, also called plateau basalt, is a massive outpouring of basaltic lava from fissures that covers vast areas; examples include the Deccan and Siberian Traps.
Flood frequency analysis
Flood frequency analysis is a statistical method relating flood magnitude at a river or coastal site to its annual exceedance probability, used in drainage design and dam safety.
Flood inundation mapping
Flood inundation mapping is the geospatial technique that maps the extent and depth of floodwater, using hydraulic models, satellite imagery, or terrain analysis, producing extent maps and depth grids.
Flood pulse
The flood pulse is the periodic inundation and drying of a river's floodplain. The 1989 Flood Pulse Concept by Junk, Bayley, and Sparks holds it drives river-floodplain productivity.
Flood risk mapping
Flood risk mapping is a geospatial method that identifies flood-prone areas and combines modeled flood extent with exposure data to support land-use planning, insurance rating, and flood risk management.
Flood routing
Flood routing is the group of methods for determining the shape and timing of a flood wave as it moves along a channel, from a known hydrograph at another point.
Flood runoff
Flood runoff: water from precipitation flowing over land surfaces, including paved urban surfaces, into streams and causing high flow. Also called stormwater or urban runoff; generated by infiltration-excess or saturation-excess overland flow.
Floodplain delineation
Floodplain delineation is the process of drawing the boundary of the area a flood of a specified magnitude would inundate, typically by intersecting predicted water levels with terrain data.
Floods in China
Floods in China, also called flooding in China, are a recurring hazard from monsoon rains on seven major rivers, with floods like those of 1931 and 1998 among history's deadliest.
Floridan Aquifer
The Floridan Aquifer is one of the world's most productive aquifers, underlying all of Florida and parts of four neighboring states and supplying drinking water to nearly 10 million people.
Flow
Environmental flow (e-flow): the quantity, timing, and quality of river flows needed to sustain freshwater ecosystems alongside human use; assessed by hydrological, habitat-simulation, and holistic methods such as Tennant, BBM, and DRIFT.
Flow duration curve
A flow duration curve (FDC) is a cumulative frequency curve showing the percentage of time specified stream discharges were equaled or exceeded, widely used in hydrology since about 1915.
Flow routing
Flow routing is the family of hydrologic methods that determines the timing and magnitude of a flood wave at a downstream point from upstream data.
Flower structure
A flower structure is an array of faults in a strike-slip fault zone that merges at depth and diverges upward like petals; positive and negative types form hydrocarbon traps.
Fluorapatite
Fluorapatite is a calcium fluoride phosphate mineral, Ca5(PO4)3F, and the most abundant member of the apatite group, forming the sedimentary phosphorite deposits that supply the world's phosphorus fertilizer.
Fluvisols
Fluvisols are young soils formed in recent river, lake, and marine deposits in floodplains, deltas, and tidal marshes, classified by stratified sediment and irregular organic matter renewed by periodic flooding, covering about 350 million hectares.
Fluxgate magnetometer
A fluxgate magnetometer is a vector instrument measuring DC and low-frequency magnetic fields via a saturating ferromagnetic core, invented in 1936 and used from space missions to submarine detection.
FLUXNET
FLUXNET is an international "network of networks" that harmonizes eddy covariance measurements of carbon, water, and energy fluxes from regional networks at over 1,000 sites worldwide.
Flysch
Flysch is a sedimentary facies of thin, regularly alternating sandstone, shale, and limestone beds deposited in deep marine basins during early mountain building; its turbidite record contrasts with molasse.
Foehn wind
A foehn wind (German: Föhn) is a warm, dry wind that descends the lee side of a mountain range, warmed and dried by adiabatic compression during its descent.
Fog
Fog is a suspension of microscopic water droplets in air at the Earth's surface, essentially a cloud in contact with the ground that reduces visibility below 1 kilometer.
Fog drip
Fog drip, also called fog precipitation or cloud water interception, is water that drips from forest canopies after fog droplets intercepted by leaves coalesce, sustaining ecosystems through rainless summers.
Fold (geology)
A fold, also called a geological fold, is a bend in rock layers, usually sedimentary bedding, produced by ductile deformation without fracturing, from microscopic wrinkles to mountain-belt scales.
Fold-and-thrust belt
A fold-and-thrust belt is a region of layered rocks deformed by folding and low-angle thrust faulting under horizontal compression, forming on the foreland side of a mountain belt.
Footprint model (micrometeorology)
A footprint model estimates the upwind surface area, or source area, contributing to a turbulent flux measured at a point above the ground, most often at an eddy-covariance tower.
Foraminifera in paleoclimatology
Foraminifera in paleoclimatology is the study of foraminiferal shells in seafloor sediments, whose oxygen isotope, trace metal, and assemblage signatures reconstruct past ocean temperature, ice volume, and salinity.
Forearc
A forearc is the region of a subduction zone between the ocean trench and the volcanic arc, hosting the shallow megathrust where the largest earthquakes nucleate.