• 0-9
  • a
  • b
  • c
  • d
  • e
  • f
  • g
  • h
  • i
  • j
  • k
  • l
  • m
  • n
  • o
  • p
  • q
  • r
  • s
  • t
  • u
  • v
  • w
  • x
  • y
  • z
  • Atlantic Seaboard (region, United States)

    Eastern Seaboard, region of the eastern United States, fronting the Atlantic Ocean and extending from Maine in the north to Florida in the south. Not merely a geographic term, the Eastern Seaboard is, historically, the part of the United States that was first settled by European immigrants and f

  • Atlantic slave trade (slavery)

    Transatlantic slave trade, segment of the global slave trade that transported between 10 million and 12 million enslaved Africans across the Atlantic Ocean to the Americas from the 16th to the 19th century. It was the second of three stages of the so-called triangular trade, in which arms,

  • Atlantic slipper shell (snail)

    slipper shell: The common Atlantic slipper shell (C. fornicata), often called slipper limpet, is about 4 cm (1.5 inches) long and yellowish; it is abundant from Nova Scotia to Texas. In addition, C. fornicata has been introduced to the west coast of the United States, the coastal waters of…

  • Atlantic South Equatorial Current (ocean current)

    equatorial current: The Atlantic South Equatorial Current is pushed westward by the Southeast Trade Winds (latitude 0°–20° S). Approaching Cape St. Roque, Brazil, it divides. One stream goes north as the Guiana Current, which in turn feeds the Caribbean Current, the equatorial countercurrents, and the Guinea Current. The…

  • Atlantic spadefish (fish)

    spadefish: The Atlantic spadefish (Chaetodipterus faber) is a western Atlantic species that ranges from New England to Brazil. It feeds primarily on marine invertebrates, particularly crustaceans and ctenophores (comb jellies).

  • Atlantic Stage (geochronology)

    Europe: Climatic change: …the succeeding climatic optimum (the Atlantic phase), which was probably wetter and certainly somewhat warmer, mixed forests of oak, elm, common lime (linden), and elder spread northward. Only in the late Atlantic period did the beech and hornbeam spread into western and central Europe from the southeast.

  • Atlantic sturgeon (fish)

    sturgeon: Distribution: The common Old World sturgeon (Acipenser sturio) occurs from Scandinavia to the Mediterranean. A very similar, closely related form, considered a separate species (A. oxyrhynchus) by some authorities, occurs along the east coast of North America. The length of these fishes is generally to

  • Atlantic tarpon (fish)

    tarpon: The Atlantic tarpon (Megalops atlanticus; alternate name Tarpon atlanticus) is found inshore in warm parts of the Atlantic, on the Pacific side of Central America, and sometimes in rivers. Also called silver king, grand écaille, and sabalo real, it habitually breaks water and gulps air. It…

  • Atlantic torpedo (fish)

    electric ray: …the shocks of the species Torpedo nobiliana were used as a treatment for gout, headache, and other maladies.

  • Atlantic Wall (German fortification, Europe)

    fortification: German channel defenses: …English Channel; this was the Atlantic Wall. The line consisted primarily of pillboxes and gun emplacements embedded in cliffsides or placed on the waterfronts of seaside resorts and ports. Included were massive blockhouses with disappearing guns, newsreels of which the Germans sent out through neutral sources in an effort to…

  • Atlantic walrus (mammal)

    walrus: There are two subspecies: the Atlantic walrus (Odobenus rosmarus rosmarus) and the Pacific walrus (O. rosmarus divergens). Male Pacific walrus are slightly larger, with longer tusks.

  • Atlantic wolffish (fish)

    wolffish: Species include the Atlantic wolffish (Anarhichas lupus), a vertically banded North Atlantic species; the spotted wolffish, or spotted catfish (A. minor), also of the North Atlantic; and the wolf-eel (Anarhichthys ocellatus), a black-spotted form found in the eastern Pacific.

  • Atlantic, Battle of the (World War II)

    Battle of the Atlantic, in World War II, a contest between the Western Allies and the Axis powers (particularly Germany) for the control of Atlantic sea routes. For the Allied powers, the battle had three objectives: blockade of the Axis powers in Europe, security of Allied sea movements, and

  • Atlantic, The (American journal)

    The Atlantic, American journal of news, literature, and opinion that was founded in 1857 and is one of the oldest and most-respected magazines in the United States. Formerly a monthly publication, it now releases 10 issues a year and maintains an online site. Its offices are in Washington, D.C. The

  • Atlantica (work by Rudbeck)

    Swedish literature: The 17th century: He proposed this idea in Atland eller Manheim (1679–1702), which, translated into Latin as Atlantica, attained European fame.

  • Atlantica (legendary island)

    Atlantis, a legendary island in the Atlantic Ocean, lying west of the Strait of Gibraltar. The principal sources for the legend are two of Plato’s dialogues, Timaeus and Critias. In the former, Plato describes how Egyptian priests, in conversation with the Athenian lawgiver Solon, described

  • Atlántico (department, Colombia)

    Atlántico, departamento, northwestern Colombia, located on the Caribbean coastal plain and bounded east by the Magdalena River. The department was established in 1905. Although it is one of Colombia’s smallest departments, Atlántico’s position at the mouth of one of the continent’s major rivers is

  • Atlantics (American baseball team)

    Los Angeles Dodgers, American professional baseball team based in Los Angeles that plays in the National League (NL). The team has won six World Series titles and 23 NL pennants. Founded in 1883, the Dodgers were originally based in Brooklyn, New York, and were known as the Atlantics. The team

  • Atlantis (legendary island)

    Atlantis, a legendary island in the Atlantic Ocean, lying west of the Strait of Gibraltar. The principal sources for the legend are two of Plato’s dialogues, Timaeus and Critias. In the former, Plato describes how Egyptian priests, in conversation with the Athenian lawgiver Solon, described

  • Atlantis (work by Donnelly)

    Ignatius Donnelly: …and most popular book was Atlantis (1882), which traced the origin of civilization to the legendary submerged continent of Atlantis. It was followed in 1883 by another work of speculation, Ragnarok: The Age of Fire and Gravel, which attempted to relate certain gravel and till deposits to an ancient near-collision…

  • Atlantis (space shuttle)

    Franklin Chang-Díaz: Other shuttle flights included the Atlantis mission in October 1989, which deployed the Galileo spacecraft that explored Jupiter, and the June 2002 flight of Endeavour, during which he participated in three space walks to help repair the robotic arm of the International Space Station. Chang-Díaz was a visiting scientist (1983–93)…

  • Atlantis II Deep (basin, Red Sea)

    Atlantis II Deep, submarine basin, the largest in the Red Sea, located at latitude 21°23′ N and longitude 38°04′ E. The Atlantis II Deep attains a maximum depth of 7,160 feet (2,170 metres) Atlantis II Deep is noteworthy because it is one of the areas containing hot brines, with water temperatures

  • Atlantoxerus getulus (rodent)

    ground squirrel: Nontropical ground squirrels: The Barbary ground squirrel (Atlantoxerus getulus) lives in rocky habitats from sea level to 4,000 metres (13,000 feet) in the Atlas Mountains of northwestern Africa, and the four species of African ground squirrels (genus Xerus) inhabit savannas and rocky deserts in northern, eastern, and southern Africa.…

  • atlas (maps)

    Atlas, a collection of maps or charts, usually bound together. The name derives from a custom—initiated by Gerardus Mercator in the 16th century—of using the figure of the Titan Atlas, holding the globe on his shoulders, as a frontispiece for books of maps. In addition to maps and charts, atlases

  • ATLAS (particle accelerator)

    Argonne National Laboratory: …Pulsed Neutron Source (IPNS), the Argonne Tandem Linear Accelerator System (ATLAS), and the High-Voltage Electron Microscope- (HVEM-) Tandem Facility—have been designated official U.S. Department of Energy National User Facilities.

  • Atlas (American launch vehicles)

    Atlas, series of American launch vehicles, designed originally as intercontinental ballistic missiles (ICBMs), that have been in service since the late 1950s. The Atlas D, the first version deployed, became operational in 1959 as one of the first U.S. ICBMs. (Atlas A, B, and C were experimental

  • Atlas (Greek mythology)

    Atlas, in Greek mythology, son of the Titan Iapetus and the Oceanid Clymene (or Asia) and brother of Prometheus (creator of humankind). In Homer’s Odyssey, Book I, Atlas seems to have been a marine creature who supported the pillars that held heaven and earth apart. These were thought to rest in

  • atlas (architecture)

    Atlas, in architecture, male figure used as a column to support an entablature, balcony, or other projection, originating in the Classical architecture of antiquity. Such figures are posed as if supporting great weights (e.g., Atlas bearing the world). The related telamon of Roman architecture,

  • Atlas (satellite of Saturn)

    Saturn: Orbital and rotational dynamics: …of such inner moons as Atlas are puzzling, and they appear to support the idea that the current ring system is much younger than Saturn itself.

  • atlas (vertebra)

    skull: …the highest vertebra, called the atlas, permitting nodding motion. The atlas turns on the next-lower vertebra, the axis, to allow for side-to-side motion.

  • Atlas (computer)

    Tom Kilburn: …most ambitious project, MUSE, renamed Atlas when Ferranti joined the project in 1959. In parallel with two similar projects in the United States (LARC and Stretch; see supercomputer) but largely independent of them, Atlas made the massive jump from running one program at a time to multiprogramming. With multiprogramming a…

  • Atlas (work by Mercator)

    Gerardus Mercator: This Atlas—the term still used to indicate a collection of maps—was never fully realized.

  • Atlas 2 (launch vehicle)

    Ellen Ochoa: …performed various experiments collectively called ATLAS-2 (Atmospheric Laboratory for Applications and Science-2) that studied the Sun and its interaction with Earth’s atmosphere. The crew also released the SPARTAN satellite, which studied the solar wind for two days before it was retrieved. She was part of the STS-66 Atlantis mission in…

  • Atlas beetle (insect subfamily)

    Rhinoceros beetle, (subfamily Dynastinae), any of numerous species of beetles, some of which are among the largest beetles on Earth, named for the impressive hornlike structures on the frontal portions of males. These beetles have rounded, convex backs, and their coloration varies from black to

  • Atlas cedar (plant)

    cedar: The Atlas cedar (C. atlantica), the Cyprus cedar (C. brevifolia), the deodar (C. deodara), and the cedar of Lebanon (C. libani) are the true cedars. They are tall trees with large trunks and massive, irregular heads of spreading branches. Young trees are covered with smooth, dark-gray…

  • Atlas Comics (American company)

    Marvel Comics, American media and entertainment company that was widely regarded as one of the “big two” publishers in the comic industry. Its parent company, Marvel Entertainment, is a wholly owned subsidiary of the Disney Company. Its headquarters are in New York City. The precursor to Marvel

  • Atlas gazelle (mammal)

    gazelle: African gazelles: The Atlas gazelle, also called Cuvier’s, or the edmi, gazelle (G. cuvieri), is found in the Atlas Mountains. The rhim, or slender-horned, gazelle (G. leptoceros) is the most desert-adapted African gazelle and lives in the Sahara’s great sand deserts (ergs) from Algeria to Egypt. The third…

  • atlas moth (insect)

    saturniid moth: …silk-producing species is the large atlas moth (Attacus atlas), whose wingspread often exceeds 25 cm (10 inches). The caterpillar of the cynthia moth (Samia cynthia or walkeri), also known as the ailanthus silk moth, native to Asia and introduced into North America, feeds chiefly on leaves of the ailanthus tree…

  • Atlas Mountains (mountains, Africa)

    Atlas Mountains, series of mountain ranges in northwestern Africa, running generally southwest to northeast to form the geologic backbone of the countries of the Maghrib (the western region of the Arab world)—Morocco, Algeria, and Tunisia. They extend for more than 1,200 miles (2,000 kilometres),

  • Atlas of Peculiar Galaxies (work by Arp)

    Halton Christian Arp: …he had included in his Atlas of Peculiar Galaxies (1966) seemed to lie in the vicinity of quasars. Using photographic evidence, Arp tried to prove that the low-redshift galaxies and the high-redshift quasars not only appear close together but also actually are connected by gaseous bridges, an impossibility if the…

  • Atlas of the Medulla and Mid-Brain, An (work by Sabin)

    Florence Rena Sabin: In 1901 she published An Atlas of the Medulla and Midbrain, which became a popular medical text. In 1902, when Johns Hopkins finally abandoned its policy of not appointing women to its medical faculty, Sabin was named an assistant in anatomy, and she became in 1917 the school’s first…

  • Atlas of the Munsell Color System (work by Munsell)

    colour: Colour atlases: …colour atlas such as the Munsell Book of Color is often used. In this system colours are matched to printed colour chips from a three-dimensional colour solid whose parameters are hue, value (corresponding to reflectance), and chroma (corresponding to purity, or saturation). These three parameters are illustrated schematically in the…

  • Atlas Saharan (mountains, Africa)

    Saharan Atlas, part of the chain of Atlas Mountains, extending across northern Africa from Algeria into Tunisia. The principal ranges from west to east are the Ksour, Amour, Ouled-Naïl, Zab, Aurès, and Tébessa (Tabassah). Mount Chélia (7,638 feet [2,328 m]) is the highest point in northern A

  • Atlas Saharien (mountains, Africa)

    Saharan Atlas, part of the chain of Atlas Mountains, extending across northern Africa from Algeria into Tunisia. The principal ranges from west to east are the Ksour, Amour, Ouled-Naïl, Zab, Aurès, and Tébessa (Tabassah). Mount Chélia (7,638 feet [2,328 m]) is the highest point in northern A

  • Atlas Shrugged (work by Rand)

    Atlas Shrugged, novel by Ayn Rand, published in 1957. The book’s female protagonist, Dagny Taggart, struggles to manage a transcontinental railroad amid the pressures and restrictions of massive bureaucracy. Her antagonistic reaction to a libertarian group seeking an end to government regulation is

  • Atlas sive Cosmographicae meditationes de Fabrica Mundi et fabricati figura (work by Mercator)

    Gerardus Mercator: This Atlas—the term still used to indicate a collection of maps—was never fully realized.

  • Atlas Tell (mountains, Africa)

    Tell Atlas, range of the Atlas Mountains in North Africa, extending about 1,000 miles (1,600 km) from eastern Morocco through Algeria to Tunisia. In Morocco, from Ceuta east to Melilla (150 miles [240 km]), the Er-Rif mountain range of the Tell Atlas faces the Mediterranean Sea, and there, as a

  • Atlas Tellien (mountains, Africa)

    Tell Atlas, range of the Atlas Mountains in North Africa, extending about 1,000 miles (1,600 km) from eastern Morocco through Algeria to Tunisia. In Morocco, from Ceuta east to Melilla (150 miles [240 km]), the Er-Rif mountain range of the Tell Atlas faces the Mediterranean Sea, and there, as a

  • Atlas, Charles (American bodybuilder)

    Charles Atlas, Italian-born American bodybuilder and physical culturist who, with Frederick Tilney and Charles P. Roman, created and marketed a highly popular mail-order bodybuilding course. In 1904 Angelo Siciliano immigrated to the United States with his mother and settled in Brooklyn, New York.

  • ATLAS-3 (launch vehicle)

    Ellen Ochoa: STS-66 carried the ATLAS-3, which reflew experiments Ochoa had worked with on her previous flight. Another small satellite, CRISTA-SPAS, was released, which studied Earth’s atmosphere for eight days before being retrieved.

  • Atlas-Centaur (launch vehicle)

    Atlas: The Atlas-Centaur rocket combined an Atlas first stage, which burned kerosene fuel, with a Centaur second stage, fueled with liquid hydrogen; it was the first rocket to use liquid hydrogen as fuel.

  • atlatl (weapon)

    Spear-thrower, a device for throwing a spear (or dart) usually consisting of a rod or board with a groove on the upper surface and a hook, thong, or projection at the rear end to hold the weapon in place until its release. Its purpose is to give greater velocity and force to the spear. In use from

  • atlatl weight (American Indian art)

    Bird stone, abstract stone carving, one of the most striking artifacts left by the prehistoric North American Indians who inhabited the area east of the Mississippi River in the United States and parts of eastern Canada. The stones resemble birds and rarely exceed 6 inches (15 cm) in length. The

  • Atlético Madrid (Spanish football team)

    Diego Forlán: Villarreal traded Forlán to Atlético Madrid in 2007, and he won the Pichichi again in 2008–09, with 32 goals. In both 2004–05 and 2008–09, he earned the Golden Shoe as the top scorer in all of Europe. In 2010 Forlán scored the winning goal for Atlético Madrid in the…

  • Atli (legendary character)

    Attila: …Nibelungenlied and under the name Atli in Icelandic sagas.

  • Atli, Lay of (medieval poem)

    Lay of Atli, heroic poem in the Norse Poetic Edda (see Edda), an older variant of the tale of slaughter and revenge that is the subject of the German epic Nibelungenlied, from which it differs in several respects. In the Norse poem, Atli (the Hunnish king Attila) is the villain, who is slain by his

  • Atlin, Lake (lake, Canada)

    Yukon River: Physiography and hydrology: …Yukon River, however, flow from Atlin Lake and Tagish Lake in the vicinity of the border between British Columbia and the Yukon territory. About 50 miles (80 km) downstream the Yukon once rushed through the rocky walls of narrow Miles Canyon and tumbled over rock ledges at Whitehorse Rapids. These…

  • ʿAtlit, Plain of (plain, Israel)

    Plain of Sharon: …River and Mount Carmel, the Plain of ʿAtlit, or the Plain of Dor.

  • Atlixco (Mexico)

    Atlixco, city, southwestern Puebla estado (state), south-central Mexico. It lies at 6,171 feet (1,881 metres) above sea level in a fertile valley irrigated by the Molinos River, which descends from the southeastern slopes of Iztaccíhuatl volcano. Founded in 1579 as Villa de Carrión, after its

  • ATM (communications)

    Lawrence Roberts: …produced networking equipment using the asynchronous transfer mode (ATM) protocol. In 1993 he became president of ATM Systems. However, ATM was eventually supplanted by networking devices using Internet Protocol (IP), and he left ATM Systems in 1998.

  • atm (unit of measurement)

    Standard atmosphere, unit of pressure, equal to the mean atmospheric pressure at sea level. It corresponds to the pressure exerted by a vertical column of mercury (as in a barometer) 760 mm (29.9213 inches) high. One standard atmosphere, which is also referred to as one atmosphere, is equivalent to

  • ATM

    money: Electronic money: …currency from their accounts using automated teller machines (ATMs). In this way an ATM withdrawal works like a debit card. ATMs also allow users to deposit checks into their accounts or repay bank loans. While they do not replace the assets used as money, ATMs make money more readily available…

  • atman (Hindu philosophy)

    Atman, (Sanskrit: “self,” “breath”) one of the most basic concepts in Hinduism, the universal self, identical with the eternal core of the personality that after death either transmigrates to a new life or attains release (moksha) from the bonds of existence. While in the early Vedas it occurred

  • Ātmārāmjī (Jain reformer and monk)

    Ātmārāmjī, important Jain reformer and revivalist monk. He was born a Hindu but as a child came under the influence of Sthānakavāsī Jain monks and was initiated as a Sthānakavāsī monk in 1854. He was renowned for his prodigious memory and intellectual skills. He pursued an independent study of J

  • Atmore (Alabama, United States)

    Atmore, city, Escambia county, southwestern Alabama, U.S. It lies just north of the Florida state line, about 50 miles (80 km) northeast of Mobile. The city was founded in 1866 by William Larkin Williams, who established a railroad supply stop that became known as Williams Station. Settlers were

  • atmosphere (gaseous envelope)

    Atmosphere, the gas and aerosol envelope that extends from the ocean, land, and ice-covered surface of a planet outward into space. The density of the atmosphere decreases outward, because the gravitational attraction of the planet, which pulls the gases and aerosols (microscopic suspended

  • atmosphere-ocean interaction

    climate: Circulation, currents, and ocean-atmosphere interaction: The circulation of the ocean is a key factor in air temperature distribution. Ocean currents that have a northward or southward component, such as the warm Gulf Stream in the North Atlantic or the cold Peru (Humboldt) Current off South America, effectively exchange…

  • Atmosphères (work by Ligeti)

    Atmosphères, orchestral composition known for its dense texture and stasis by avant-garde Hungarian-born composer György Ligeti. It was commissioned by Southwest German Radio and premiered at the Festival of Contemporary Music in Donaueschingen, West Germany, on October 22, 1961. But the piece

  • atmospheric absorption (telecommunications)

    telecommunications media: The free-space channel: Atmospheric absorption losses can be minimized by choosing transmission wavelengths that lie in one of the low-loss “windows” in the infrared, visible, or ultraviolet region. The atmosphere imposes high absorption losses as the optical wavelength approaches the resonant wavelengths of gaseous constituents such as oxygen…

  • atmospheric arc lamp

    lamp: Modern electrical light sources: By the mid-20th century the atmospheric arc lamp was used chiefly in large-wattage units for searchlights, for projectors calling for a high intensity and concentrated source, and for other special applications requiring small but powerful sources of blue and ultraviolet energy.

  • atmospheric boundary layer (atmospheric science)

    Planetary boundary layer (PBL), the region of the lower troposphere where Earth’s surface strongly influences temperature, moisture, and wind through the turbulent transfer of air mass. As a result of surface friction, winds in the PBL are usually weaker than above and tend to blow toward areas of

  • atmospheric brown cloud

    Atmospheric brown cloud, a layer of air pollution containing aerosols such as soot or dust that absorb as well as scatter incoming solar radiation, leading to regional and global climatic effects and posing risks to human health and food security. This layer extends from Earth’s surface to an

  • atmospheric circulation (meteorology)

    Atmospheric circulation, any atmospheric flow used to refer to the general circulation of the Earth and regional movements of air around areas of high and low pressure. On average, this circulation corresponds to large-scale wind systems arranged in several east–west belts that encircle the Earth.

  • atmospheric convergence (atmospheric)

    Convergence and divergence, in meteorology, the accumulation or drawing apart of air, as well as the rate at which each takes place. The terms are usually used to refer specifically to the horizontal inflow (convergence) or outflow (divergence) of air. The convergence of horizontal winds causes

  • atmospheric corona (meteorology)

    Atmospheric corona, set of one or more coloured rings that sometimes appear close to the Sun or Moon when they are viewed through a thin cloud composed of water droplets. They are caused by the diffraction of light around the edges of the droplets, with each colour being deviated through a slightly

  • atmospheric divergence (atmospheric)

    convergence and divergence: divergence, in meteorology, the accumulation or drawing apart of air, as well as the rate at which each takes place. The terms are usually used to refer specifically to the horizontal inflow (convergence) or outflow (divergence) of air. The convergence of horizontal winds causes air…

  • atmospheric electricity

    Atmospheric electricity, electrical phenomena that occur in the lower atmosphere, usually the troposphere—e.g., the production, transport, and loss of free electrical charges; the change in electrical potential from point to point in the atmosphere; and the atmosphere’s electrical conductivity.

  • atmospheric general circulation model (climatology)

    scientific modeling: …model of note is the general circulation model, which is used for simulating human- and non-human-induced climate change. Modeling of geologic events, such as convection within Earth and theoretical movements of Earth’s plates, has advanced scientists’ knowledge of volcanoes and earthquakes and of the evolution of Earth’s surface. In ecology,…

  • atmospheric humidity (atmosphere)

    Humidity, the amount of water vapour in the air. It is the most variable characteristic of the atmosphere and constitutes a major factor in climate and weather. A brief treatment of humidity follows. For full treatment, see climate: Atmospheric humidity and precipitation. Atmospheric water vapour

  • Atmospheric Imaging Assembly (scientific research instrument)

    Solar Dynamics Observatory: …and Magnetic Imager (HMI), the Atmospheric Imaging Assembly (AIA), and the Extreme Ultraviolet Variability Experiment (EVE). HMI studies changes in the Sun’s magnetic field by capturing images of the Sun in polarized light every 50 seconds. AIA observes the solar corona in eight wavelengths of ultraviolet light every 10 seconds.…

  • Atmospheric Laboratory for Applications and Science (United States space laboratory)

    Kathryn Sullivan: …the payload commander of the Atmospheric Laboratory for Applications and Science, a laboratory on a pallet housed in the space shuttle Atlantis’s cargo bay that contained 12 experiments studying Earth’s atmosphere.

  • Atmospheric Laboratory for Applications and Science-2 (launch vehicle)

    Ellen Ochoa: …performed various experiments collectively called ATLAS-2 (Atmospheric Laboratory for Applications and Science-2) that studied the Sun and its interaction with Earth’s atmosphere. The crew also released the SPARTAN satellite, which studied the solar wind for two days before it was retrieved. She was part of the STS-66 Atlantis mission in…

  • Atmospheric Laboratory for Applications and Science-3 (launch vehicle)

    Ellen Ochoa: STS-66 carried the ATLAS-3, which reflew experiments Ochoa had worked with on her previous flight. Another small satellite, CRISTA-SPAS, was released, which studied Earth’s atmosphere for eight days before being retrieved.

  • atmospheric modeling (climatology)

    numerical analysis: Applications: Another important application is atmospheric modeling. In addition to improving weather forecasts, such models are crucial for understanding the possible effects of human activities on the Earth’s climate. In order to create a useful model, many variables must be introduced. Fundamental among these are the velocity V(x, y, z,…

  • atmospheric optics

    Atmospheric optics, study of optical characteristics and phenomena associated with the interaction of visible sunlight with atmospheric gases, particulates, and water vapour. Refraction, diffraction, Rayleigh scattering (qq.v.), and polarization of light are within the compass of atmospheric

  • atmospheric perspective (art)

    Aerial perspective, method of creating the illusion of depth, or recession, in a painting or drawing by modulating colour to simulate changes effected by the atmosphere on the colours of things seen at a distance. Although the use of aerial perspective has been known since antiquity, Leonardo da

  • atmospheric pollution

    Air pollution, release into the atmosphere of various gases, finely divided solids, or finely dispersed liquid aerosols at rates that exceed the natural capacity of the environment to dissipate and dilute or absorb them. These substances may reach concentrations in the air that cause undesirable

  • atmospheric pressure

    Atmospheric pressure, force per unit area exerted by an atmospheric column (that is, the entire body of air above the specified area). Atmospheric pressure can be measured with a mercury barometer (hence the commonly used synonym barometric pressure), which indicates the height of a column of

  • atmospheric propagation (communications)

    telecommunications media: Radio-wave propagation: …a combination of three mechanisms: atmospheric wave propagation, surface wave propagation, and reflected wave propagation. They are described below.

  • atmospheric refraction (physics)

    Atmospheric refraction, change in the direction of propagation of electromagnetic radiation or sound waves in traversing the atmosphere. Such changes are caused by gradients in the density of the air. See

  • Atmospheric Research and Environment Programme

    World Meteorological Organization: …including global warming; and the Atmospheric Research and Environment Programme, which was designed to promote research on issues such as ozone depletion.

  • atmospheric satellite drag (astronomy)

    space weather: Atmospheric satellite drag: Though the uppermost layer of Earth’s atmosphere, the thermosphere, is extremely tenuous compared with the dense lower layer at the surface, it is not a perfect vacuum. Indeed, the density of the gas a few hundred kilometres above Earth’s surface is appreciable…

  • atmospheric scattering (telecommunications)

    telecommunications media: The free-space channel: …beam divergence, atmospheric absorption, and atmospheric scattering. Beam divergence can be minimized by collimating (making parallel) the transmitted light into a coherent narrow beam by using a laser light source for a transmitter. Atmospheric absorption losses can be minimized by choosing transmission wavelengths that lie in one of the low-loss…

  • atmospheric science

    Atmospheric science, interdisciplinary field of study that combines the components of physics and chemistry that focus on the structure and dynamics of Earth’s atmosphere. Mathematical tools, such as differential equations and vector analysis, and computer systems are used to evaluate the physical

  • atmospheric seeing (astronomy)

    Seeing, in astronomy, sharpness of a telescopic image. Seeing is dependent upon the degree of turbulence in the Earth’s atmosphere for a given telescope. Scintillation, the “twinkling” of stars to the unaided eye, is a commonly known result of turbulence in the higher reaches of the atmosphere.

  • atmospheric tide (physics)

    tide: Atmospheric and other tides: Atmospheric tides are detectable meteorological phenomena but are a comparatively minor component in atmospheric motions. An Earth tide differs from oceanic and atmospheric ones in that the response to it is an elastic deformation rather than a flow. Observations of Earth tides contribute to knowledge…

  • atmospheric turbulence (meteorology)

    Atmospheric turbulence, small-scale, irregular air motions characterized by winds that vary in speed and direction. Turbulence is important because it mixes and churns the atmosphere and causes water vapour, smoke, and other substances, as well as energy, to become distributed both vertically and

  • atmospheric wave propagation (communications)

    telecommunications media: Radio-wave propagation: …a combination of three mechanisms: atmospheric wave propagation, surface wave propagation, and reflected wave propagation. They are described below.

  • Atocha Station (station, Madrid, Spain)

    Madrid train bombings of 2004: …four trains in and around Atocha Station in the city’s centre, leaving 191 dead and more than 1,800 injured. Occurring just three days before Spain’s general elections, the attacks had major political consequences.

  • atol (beverage)

    Atole, a hot Mexican beverage typically made from masa (corn dough) or masa harina (dough flour), water, and spices. Sometimes it is made with oatmeal, rice, barley, or wheat instead of masa. The drink is commonly prepared by toasting the masa on a griddle before mixing in water, sugar, vanilla,

  • Your preference has been recorded
    Check out Britannica's new site for parents!
    Subscribe Today!