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Viridien
Viridien, known as CGG (Compagnie Générale de Géophysique) until its 2024 rebrand, is a French geoscience, seismic imaging, and Earth data company headquartered in Paris, with about 3,500 employees worldwide.
Virtual temperature
Virtual temperature, also called density temperature, is the temperature dry air would have at the same pressure and density as a given sample of moist air.
Visibility
Visibility in meteorology is the greatest distance at which an object can be seen and recognized, a standard weather observation used as a proxy for particulate air pollution.
Visual MODFLOW
Visual MODFLOW is a commercial graphical interface for three-dimensional groundwater flow and contaminant transport modeling built around the USGS MODFLOW code, first released in 1994 by Waterloo Hydrogeologic.
Vitrinite reflectance
Vitrinite reflectance (Rₒ) is the percentage of light reflected from vitrinite, woody plant matter in sedimentary rocks, and is the standard geothermometer for their thermal maturity.
Vitus Bering
Vitus Jonassen Bering (1681–1741) was a Danish-born navigator in the Russian navy who led the Kamchatka expeditions, proved Asia and America are separated by sea, and reached Alaska in 1741.
Vivianite
Vivianite, also called blue iron earth, is a hydrated ferrous iron phosphate mineral, colorless when fresh but turning blue on oxidation, found in bogs and sediments.
Vladimir Vernadsky
Vladimir Vernadsky, also known as Vladimir Ivanovich Vernadsky, was a Russian and Ukrainian mineralogist and geochemist who developed the modern concept of the biosphere and framed the noosphere.
Volcán de Fuego
Volcán de Fuego (Chiq'aq', "Fireplace"), also known as Fuego volcano, is a persistently active basaltic stratovolcano in southern Guatemala and Central America's historically most active volcano.
Volcanic area
Volcanic area: a region containing volcanoes, volcanic landforms, or volcanic deposits. Also called volcanic region or volcanic field; about 1,350 potentially active volcanoes worldwide, 800 million people within 100 km, organized by tectonic setting.
Volcanic ash
Volcanic ash, also called volcanic dust, is hard, abrasive tephra finer than 2 mm thrown out by explosive eruptions, the most widespread volcanic hazard and a serious threat to aircraft.
Volcanic crater
A volcanic crater is an enclosed depression at or around a volcanic vent, formed by explosive eruption or ground collapse; a collapse more than 1 kilometer across is a caldera.
Volcanic Eruptions
Volcanic eruptions: explosive or effusive release of magma, gas, and ash at Earth's surface. Named types include Hawaiian, Strombolian, Vulcanian, Peléan, and Plinian; hazards include pyroclastic flows, lahars, and ashfall.
Volcanic explosivity index
The volcanic explosivity index (VEI) is a 0 to 8 scale proposed in 1982 by Chris Newhall and Stephen Self to compare explosive eruptions by tephra volume.
Volcanic field
A volcanic field is a cluster of volcanoes or an area covered by volcanic rocks, in which individual centers usually erupt only once; fields may span millions of years.
Volcanic gas
Volcanic gas is the mixture of gases released from magma and volcanic vents, mainly water vapor, carbon dioxide, and sulfur dioxide, even when a volcano is not erupting.
Volcanic rock
Volcanic rock, also known as effusive rock or extrusive igneous rock, is rock formed when magma cools at or near Earth's surface, producing lavas and pyroclastic rocks such as basalt, the most common type.
Volcanic tremor
Volcanic tremor is a continuous seismic signal generated at volcanoes by the movement of magma, gas, or groundwater, lasting from minutes to days and widely used in eruption monitoring.
Volcanic winter
A volcanic winter is a period of global surface cooling caused by an explosive eruption injecting sulfur dioxide into the stratosphere, typically lasting two to three years.
Volcanic winter of 536
The volcanic winter of 536 was the severe dimming and cooling of the Northern Hemisphere after a major volcanic eruption, the coldest episode in the last two millennia.
Volcanism
Volcanism: eruption of molten rock (magma) onto a planetary surface through vents called volcanoes. Driven by internal heat on Earth, Venus, Mars, tidally heated Io, and icy moons; studied comparatively across the Solar System and exoplanets.
Volcanism of Iceland
Volcanism of Iceland, where the Mid-Atlantic Ridge crosses the Iceland plume, makes Iceland one of Earth's most volcanically active areas, averaging an eruption every four to five years.
Volcanism on Venus
Volcanism on Venus is the volcanic activity that shaped the planet's surface, which holds more than 85,000 volcanoes and shows possible ongoing eruptions seen by the Magellan spacecraft.
Volcano
A volcano is a vent, or a landform built around one, on Earth or another planet through which molten rock, rock fragments, and gases erupt; most active ones encircle the Pacific as the Ring of Fire.
Volcanogenic massive sulfide deposit
A volcanogenic massive sulfide deposit is metal-rich sulfide ore, mainly pyrite, formed at or near the seafloor by hydrothermal fluids, and a major source of copper, zinc, lead, gold, and silver.
Volgian
The Volgian is a regional Late Jurassic geologic stage named after the Volga River, proposed by S.N. Nikitin in 1881 and still used across the Boreal realm.
Voluntary carbon market
The voluntary carbon market is a market where companies and individuals voluntarily buy carbon credits, each typically representing one ton of CO2 reduced or removed, to offset emissions.
VORTEX projects
The VORTEX projects are a series of NOAA tornado field research campaigns run since 1994, including VORTEX2 (2009–2010) and VORTEX-Southeast (2016–2018), coordinated largely through the National Severe Storms Laboratory in Norman, Oklahoma.
Vorticity equation
The vorticity equation is the evolution equation for vorticity, the curl of a fluid's velocity, governing rotation changes through stretching, tilting, baroclinic generation, and diffusion.
Vostok ice core
The Vostok ice core is a deep ice core drilled at Vostok Station in central East Antarctica, preserving trapped gases and climate records spanning roughly 420,000 years.