5,021 articles
Vredefort impact structure
The Vredefort impact structure, also known as the Vredefort Crater, is the eroded remnant of the largest confirmed meteorite impact crater on Earth, formed in South Africa 2,023 million years ago.
Vysoky
Vysoky (Vysokii, Visoky), volcano 300221, a 2,129 m Holocene stratovolcano in Kamchatka's Eastern Volcanic Arc, 4 km NE of Komarov; last confirmed eruption about 550 BCE (VEI 0), not the Slovak mountain Vysoká.
Wackestone
Wackestone is a mud-supported carbonate rock, usually a limestone, with more than 10 percent grains floating in carbonate mud, defined in Robert Dunham's 1962 classification between mudstone and packstone.
Wadati–Benioff zone
A Wadati–Benioff zone, also called the Benioff zone, is an inclined zone of earthquake foci tracing a subducting oceanic plate, reaching depths of about 700 km.
Wadsleyite
Wadsleyite is a high-pressure polymorph of olivine that dominates the upper mantle transition zone at 410 to 520 km depth and can store up to 3.3 wt% water.
Waffle House Index
The Waffle House Index is an informal, color-coded gauge of disaster severity, read from whether local Waffle House restaurants are open, on limited menu, or closed.
Wahweap Formation
Wahweap Formation: Upper Cretaceous (Campanian, about 82.2 to 77.3 Ma) sandstone and mudstone unit on Utah's Kaiparowits Plateau, overlying the Straight Cliffs Formation, with Diabloceratops, Lythronax, and early hadrosaur fossils.
Walker Lake (Nevada)
Walker Lake is a terminal lake in Mineral County, Nevada, fed by the Walker River with no outlet. Agricultural diversions have shrunk it and killed its native fish.
Walker Lane
The Walker Lane is a zone of strike-slip and normal faults in eastern California and western Nevada that carries about 20 percent of the motion between the Pacific and North American plates.
Wall cloud
A wall cloud, or pedestal cloud, is a localized, often rotating lowering from a thunderstorm's rain-free base; rotating ones usually develop before strong or violent tornadoes.
Warm conveyor belt
The warm conveyor belt is a warm, moist airstream rising from an extratropical cyclone's warm sector into the upper troposphere, producing most of its cloud and precipitation.
Warm front
A warm front is the boundary at the leading edge of an advancing warm air mass replacing cooler air, marked on weather maps by a red line with semicircles.
Warm rain
Warm rain is precipitation formed entirely in clouds warmer than 0 °C when droplets collide and coalesce into raindrops, with no ice phase involved; it dominates in the tropics.
Warming center
A warming center, also called a warm bank, is a short-term heated facility opened during extreme cold, primarily to protect homeless people from cold-related illness and death.
Warming stripes
Warming stripes, also called climate stripes, are graphics where each colored bar shows one year's temperature, blue for cooler and red for warmer, created in 2018.
Warn-on-Forecast
Warn-on-Forecast is a NOAA research program, begun at the National Severe Storms Laboratory in 2009, that forecasts tornadoes, hail, wind, and flash flooding from individual thunderstorms up to 6 hours ahead.
Wasatch Fault
The Wasatch fault zone is Utah's longest and most active normal fault, a 400 km series of segments along the base of the Wasatch Range.
Wasatch Formation
The Wasatch Formation is a widespread unit of Paleocene and Eocene continental sedimentary rocks in the Rocky Mountain region, named by Ferdinand Hayden in 1869 for exposures near Evanston, Wyoming.
Water activity
Water activity (aw) is the ratio of a substance's water vapor pressure to that of pure water, measuring free moisture. Key in food preservation and microbial limits: FDA threshold 0.85, C. botulinum minimum about 0.93.
Water balance
A water balance, also called a water budget, is an accounting of water entering, leaving, and stored within a system such as a watershed, based on conservation of mass.
Water content
Water content, also known as moisture content, is the amount of water held in a soil, expressed gravimetrically by mass or volumetrically, and widely monitored in agriculture and hydrology.
Water cycle
The water cycle, also called the hydrologic cycle, is the continuous movement of water among oceans, atmosphere, and land, driven by solar energy and gravity.
Water distribution on Earth
Water distribution on Earth describes how about 332.5 million cubic miles of water is split among oceans, ice, groundwater, and surface waters, with over 96 percent saline.
Water erosion
Water erosion: detachment and removal of soil by raindrop impact and runoff, in sheet, rill, gully, and streambank forms; predicted with USLE/RUSLE models developed by USDA research since 1929.
Water Erosion Prediction Project model
The Water Erosion Prediction Project (WEPP) model is a process-based, continuous-simulation computer model predicting water erosion on hillslopes and sediment yield from small watersheds, developed for USDA conservation agencies and delivered in 1995.
Water footprint
A water footprint is the volume of freshwater consumed and polluted to produce a product, measured over the full supply chain. The concept was developed by Arjen Y. Hoekstra in 2002.
Water level
Water level, also called stage or gauge height, is the elevation of a water surface in a stream, lake, reservoir, or well relative to a specified datum. It is the fundamental hydrological measurement, converted to discharge via a rating curve and recorded continuously at gauging stations.
Water Movements
Water Movements covers ocean currents, tides, and waves: wind-driven surface currents and gyres, thermohaline deep circulation, tidal currents, rip currents, and wave formation, with speeds, timescales, and drivers distinguishing each type.
Water resources
Water resources are the stocks of water available for use, including groundwater and non-marine surface water; agriculture accounts for roughly 70% of global freshwater withdrawals.
Water sampling
Water sampling is the collection of water from streams, lakes, groundwater wells, and the ocean for physical, chemical, or biological analysis, using grab, composite, and discharge-weighted methods.