Earth Sciences, UMB-WHY
The Earth sciences are the fields of study concerned with the solid Earth, its waters, and the air that envelops it. Included are the geologic, hydrologic, and atmospheric sciences.
Earth Sciences Encyclopedia Articles By Title
undertow
undertow, a strong seaward bottom current returning the water of broken waves back out to sea. There is in fact......
uniformitarianism
uniformitarianism, in geology, the doctrine suggesting that Earth’s geologic processes acted in the same manner......
Unzen, Mount
Mount Unzen, volcano on central Shimabara Peninsula, western Kyushu, Japan. Mount Unzen is actually a group of......
Updraft and downdraftdowndraft
Updraft and downdraftdowndraft, in meteorology, upward-moving and downward-moving air currents, respectively, that......
uplift
uplift, in geology, an increase in the vertical elevation of Earth’s surface in response to natural causes. Broad,......
uraninite
uraninite, a major ore mineral of uranium, uranium dioxide (UO2). Uraninite usually forms black, gray, or brown......
uranium-234–uranium-238 dating
uranium-234–uranium-238 dating, method of age determination that makes use of the radioactive decay of uranium-238......
uranium-thorium-lead dating
uranium-thorium-lead dating, method of establishing the time of origin of a rock by means of the amount of common......
urban climate
urban climate, any set of climatic conditions that prevails in a large metropolitan area and that differs from......
uvarovite
uvarovite, calcium chromium garnet found as small, brilliant, green crystals. It is the rarest of all the garnets,......
vadose zone
vadose zone, region of aeration above the water table. This zone also includes the capillary fringe above the water......
Valanginian Stage
Valanginian Stage, second of six main divisions (in ascending order) in the Lower Cretaceous Series, representing......
Van Allen radiation belt
Van Allen radiation belt, doughnut-shaped zones of highly energetic charged particles trapped at high altitudes......
Van earthquake of 2011
Van earthquake of 2011, severe earthquake that struck near the cities of Erciş and Van in eastern Turkey on October......
vanadate mineral
vanadate mineral, any of the many naturally occurring compounds of vanadium (V), oxygen (O), and various metals;......
vanadinite
vanadinite, vanadium mineral in the pyromorphite series of the apatite group of phosphates, lead chloride vanadate,......
variscite
variscite, phosphate mineral, hydrated aluminum phosphate (AlPO4·2H2O), which is valued as a semiprecious gemstone......
varved deposit
varved deposit, any form of repetitive sedimentary rock stratification, either bed or lamination, that was deposited......
vein
vein, in geology, ore body that is disseminated within definite boundaries in unwanted rock or minerals (gangue).......
Venezuelan earthquakes of 2026
Venezuelan earthquakes of 2026, a pair of severe earthquakes that struck northwestern Venezuela on June 24, 2026,......
ventifact
ventifact, stone that has received one or more highly polished, flattened facets as a result of erosion by windblown......
vermiculite
vermiculite, clay mineral similar to montmorillonite in structure and, in some cases, composition. Vermiculite......
Vertisol
Vertisol, one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO).......
Vertisol
Vertisol, one of the 12 soil orders in the U.S. Soil Taxonomy. Vertisols are clay-rich soils that undergo significant......
vesuvianite
vesuvianite, common silicate mineral that occurs in crystalline limestones near their contacts with igneous rocks,......
Vesuvius
Vesuvius, active volcano that rises above the Bay of Naples on the plain of Campania in southern Italy. Its western......
Virgilian series
Virgilian series, major division of Late Carboniferous rocks and time in the United States (the Late Carboniferous......
Viséan Stage
Viséan Stage, second of three internationally defined stages of the Mississippian Subsystem of the Carboniferous......
vivianite
vivianite, phosphate mineral, hydrated iron phosphate [Fe3(PO4)2·8H2O], that occurs as colourless when freshly......
volcanic eruption
volcanic eruption, an eruption of molten rock, hot rock fragments, and hot gases through a volcano, which is a......
volcanic glass
volcanic glass, any glassy rock formed from lava or magma that has a chemical composition close to that of granite......
volcanic winter
volcanic winter, cooling at Earth’s surface resulting from the deposition of massive amounts of volcanic ash and......
volcanism
volcanism, any of various processes and phenomena associated with the surficial discharge of molten rock, pyroclastic......
volcano
volcano, vent in the crust of Earth or another planet or satellite, from which issue eruptions of molten rock,......
- Introduction
- Lava, Gas, Hazards
- Ash Falls, Eruptions, Magma
- Secondary Damage, Eruptions, Hazards
- Eruptions, Types, Magma
- Pinatubo, Philippines, 1991
- Hawaii, Mauna Loa, 1984
- Vesuvius, Tambora, Krakatoa, Pelee
- Forecasting, Warning, Monitoring
- Eruptions, Cone, Magma
- Calderas, Magma, Eruptions
- Lava Domes, Magma, Eruptions
- Eruptions, Magma, Structure
- Hot Springs, Geysers, Magma
- Plate Boundaries, Magma, Eruptions
- Rift, Magma, Eruptions
- Magma, Eruptions, Geothermal
volcanology
volcanology, discipline of the geologic sciences that is concerned with all aspects of volcanic phenomena. Volcanology......
Waal Interglacial Stage
Waal Interglacial Stage, division of Pleistocene time and deposits in the Netherlands and northern Europe (the......
wacke
wacke, sedimentary rock composed of sand-sized grains (0.063–2 mm [0.0025–0.078 inch]) with a fine-grained clay......
wad
wad, black and earthy substance that consists mainly of hydrated manganese oxides; it is an important ore of manganese.......
wairakite
wairakite, hydrated calcium aluminosilicate mineral present in hot-spring deposits, notably those at Wairakei,......
Water cycle
Water cycle, cycle that involves the continuous circulation of water in the Earth-atmosphere system. Of the many......
water mass
water mass, body of ocean water with a distinctive narrow range of temperature and salinity and a particular density......
water table
water table, upper level of an underground surface in which the soil or rocks are permanently saturated with water.......
Waterberg Series
Waterberg Series, major division of rocks in southern Africa. The age of the Waterberg is in doubt; it is possible......
waterspout
waterspout, a small-diameter column of rapidly swirling air in contact with a water surface. Waterspouts are almost......
Waucoban Series
Waucoban Series, lowermost Cambrian rocks (the Cambrian Period lasted from 542 million to 488 million years ago);......
wave
wave, a ridge or swell on the surface of a body of water, normally having a forward motion distinct from the oscillatory......
wavellite
wavellite, hydrated aluminum phosphate [Al3(PO4)2(OH)3·5H2O], a common phosphate mineral that typically occurs......
Weather
Weather, state of the atmosphere at a particular place during a short period of time. It involves such atmospheric......
Weather bureau
Weather bureau, agency established by many countries to observe and report the weather and to issue weather forecasts......
Weather forecasting
Weather forecasting, the prediction of the weather through application of the principles of physics, supplemented......
Weather map
Weather map, any map or chart that shows the meteorological elements at a given time over an extended area. The......
weather modification
weather modification, the deliberate or the inadvertent alternation of atmospheric conditions by human activity,......
weathering
weathering, disintegration or alteration of rock in its natural or original position at or near the Earth’s surface......
Weichsel Glacial Stage
Weichsel Glacial Stage, major division of late Pleistocene deposits and time in western Europe (the Pleistocene......
Wenlock Series
Wenlock Series, the second of four main divisions (in ascending order) of the Silurian System, representing those......
West African monsoon
West African monsoon, a major wind system that affects West African regions between latitudes 9° and 20° N and......
Wet equatorial climate
Wet equatorial climate, major climate type of the Köppen classification characterized by consistently high temperatures......
Whakaari/White Island
Whakaari/White Island, island in the Bay of Plenty, 43 miles (69 km) west of Cape Runaway, eastern North Island,......
What causes a drought?
Droughts occur when evaporation and transpiration rates consistently exceed precipitation over an extended period......
What causes a rainbow?
What causes a rainbow?, The formation of a rainbow begins with the refraction of sunlight as it enters a raindrop.......
What Causes a Volcano to Erupt?
Volcanic eruptions are among the most stunning phenomena in the natural world. Volcanoes erupt because of the way......
What causes acid rain?
The main contributors to acid rain are sulfur dioxide (SO2) and nitrogen oxides (NOx; the combination of NO and......
What causes soil erosion?
Soil erosion, like rock erosion, is caused by the movement of water and wind, and glaciers. Since soil (whether......
What Causes the Northern and Southern Lights?
The auroras—the aurora borealis (or northern lights) in the Northern Hemisphere, and the aurora australis (the......
What causes thunder after lightning?
Thunder is caused by the rapid expansion of air heated by a lightning discharge. When lightning strikes, it heats......
What causes tides in the ccean?
The main cause of tides in the ocean are the gravitational forces exerted by the Moon and the Sun on Earth. When......
What Causes Tsunamis?
As natural disasters go, tsunamis are among the worst in terms of overall destruction and loss of life. They rival......
What Happens to Earth If the Amazon Rainforest Is Completely Burned?
Metaphorically speaking, the vast tropical rainforest in South America’s Amazon River basin is often called the......
What Is an Aftershock?
Earth is an active place full of storms, fast-moving river and ocean currents, volcanoes, and earthquakes. Continents......
What Is Earth’s Velocity?
Earth has several velocities. There is the velocity with which it rotates on its axis. A point on Earth’s Equator......
What Is Known (and Not Known) About Contrails
Contrail is short for “condensation trail.” A condensation trail is a streamer of cloud sometimes observed behind......
What Is Relative Humidity?
Relativity, in our understanding, depends on the value of one thing compared to another. For example, a mouse is......
What is the coldest temperature ever recorded on Earth?
Antarctica holds the record for the lowest temperature ever recorded on Earth. At Vostok Station, a Russian research......
What Is the Difference Between a Meteotsunami, a Seiche, and a Storm Surge?
A meteotsunami is a large sea wave, with a wave height of two metres (about 6 feet) or more. Unlike seismic tsunamis,......
What Is the Difference Between a Typhoon and a Super Typhoon?
The terms typhoon and hurricane are regional names for the same weather phenomenon, the tropical cyclone. Tropical......
What Is the Difference Between El Niño and La Niña?
Every few years the phenomenon known as El Niño dominates the headlines. In other years its climatic alter ego......
What Is the U.S. Environmental Protection Agency’s Endangerment Finding?
In everyday usage endanger is a loaded word that evokes images of people being exposed to disease, workers at risk......
What Makes a Wave Go Rogue?
Many a tall tale has been inspired by the world’s oceans, from stories of mysterious sea monsters to legends about......
What Was the Little Ice Age?
When most people think of ice ages, or “glacial ages,” they often envision cavemen, woolly mammoths, and vast plains......
What would happen if Earth stopped rotating?
A sudden halt in Earth’s rotation would cause severe and widespread disruption to the planet’s physical structure,......
What’s the Difference Between Global Warming and Climate Change?
People often confuse the concepts of global warming and climate change, and it doesn’t help that media companies......
What’s the Difference Between Weather and Climate?
Adding confusion to the politics of climate change and global warming in the press is the assumption that the terms......
When Does Summer Start?
Many climate scientists define the start of summer in terms of meteorological phenomena and the calendar year.......
When Katrina Struck
Between August 23 and 29, 2005, a tropical depression called “Katrina” grew into one of the most destructive storms......
whirlpool
whirlpool, rotary oceanic current, a large-scale eddy that is produced by the interaction of rising and falling......
whirlwind
whirlwind, a small-diameter columnar vortex of rapidly swirling air. A broad spectrum of vortices occurs in the......
Why Are Clouds White?
Clouds appear white because of the nature of the incident light and the way this light is scattered by them. Sunlight......
Why are higher elevations colder?
Higher elevations are colder primarily due to the decrease in atmospheric pressure that results from the expansion......
Why Are Hurricanes Rare in Hawaii?
One would think that a group of tropical islands that lie just south of the Tropic of Cancer would be a prime target......
Why are rainbows curved?
Rainbows are curved because of the way sunlight interacts with water droplets in the atmosphere. When sunlight......
Why are rip currents dangerous?
Rip currents are dangerous primarily because they are often more powerful than they initially seem and move quickly,......
Why do stars twinkle?
Light emitted from stars does not actually twinkle but only appears to twinkle when viewed from Earth. As starlight......
Why do we have seasons?
Seasons occur due to the tilt of Earth’s axis, which is approximately 23.5°. Because of this tilt, each hemisphere......
Why Does a Mushroom Cloud Look Like a Mushroom?
A mushroom cloud is the iconic and terrifying result of a thermonuclear explosion, but actually a mushroom cloud......
Why does the Earth rotate?
The Earth rotates because of the conservation of angular momentum acquired from the rotation of the solar nebula,......
Why Does the Tropic of Cancer’s Location on Earth Move Over Time?
The Tropic of Cancer is a line of latitude approximately 23°27′ north of Earth’s Equator. This latitude corresponds......
Why Does the United States Have More Tornadoes than Any Other Country?
The United States experiences the most tornadoes of any country in the world: more than 1,000 per year have been......
Why Is Earth’s Axis Tilted?
Earth rotates eastward, a counterclockwise motion when viewed from a point above the North Pole. The hypothetical......
Why Is Predicting the Weather So Difficult for Meteorologists?
Simply stated, predicting the future is hard work, and meteorologists should never be expected to get things exactly......
Why is summer warmer than winter?
The temperature people feel outside is largely based on the absorption of radiant energy from the Sun. Differing......