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  • Ain, Al- (United Arab Emirates)
    city in Al-Buraymī oasis, southeastern Abū Ẓaby emirate, United Arab Emirates. The oasis city consists of houses of dried earth in a large palm grove; it also has a modern mosque and many gardens. Al-ʿAyn is situated in a large expanse of fertile land at the foot of Mount Ḥafīt. Grave mounds at Al-ʿAyn have tomb...
  • Aïn Beïda (Algeria)
    town, northeastern Algeria. It is situated on a plateau at the eastern edge of the Sétif plains. The plateau, once occupied by a large lake, now has several shallow depressions containing saline lakes. Sheltered on the east by wooded hills, Aïn Beïda is in a grain-producing area irrigated by wells and springs....
  • Aïn Bessem (Algeria)
    The surrounding region is encompassed by the ranges and valleys of the Tell Atlas. Although it is principally a region of olive and cereal cultivation, there are also vineyards near Aïn Bessem in the north. Sour el-Ghozlane in the drier south is a trading centre for horses, cattle, and sheep. Pop. (latest est.) mun., 53,065....
  • Aïn el-Hanech (archaeological site, Algeria)
    Although there is uncertainty about some factors, Aïn el-Hanech (in Algeria) is the site of one of the earliest traces of hominin occupation in the Maghrib. Somewhat later but better-attested are sites at Ternifine (near Tighenif, Algeria) and at Sidi Abd el-Rahmane, Morocco. Hand axes associated with the hominin Homo erectus have been found at Ternifine, and Sidi Abd el-Rahmane has....
  • Ain Jalut, Battle of (Syrian history)
    (Sept. 3, 1260), decisive victory of the Mamlūks of Egypt over the invading Mongols, which saved Egypt and Islām and halted the westward expansion of the Mongol empire....
  • Ain River (river, France)
    river, eastern France, flowing 124 miles (200 km) southward from the Jura Plateau through Jura and Ain départements. The river emerges from its gorge near Pont-d’Ain, having powered several hydroelectric stations (the largest of which is the Barrage de Vouglans). The Ain then crosses the Dombes lowlands and joins the Rhône River. The river’s principal affluents ...
  • Aïn Salah (Algeria)
    oasis town, central Algeria, on the southern edge of the arid Tademaït Plateau. At the crossing of ancient trans-Saharan caravan routes, it was once an important trade link between northern and central Africa but has declined in modern times owing to high transportation costs and the exodus of workers to the developing gas fields 60 miles (100 km) southwest. Mainly visite...
  • Aïn Sefra (Algeria)
    town, western Algeria. It is situated in the Saharan Atlas, 28 miles (45 km) east of the Moroccan border. The town lies in a broad valley between Mount Aïssa and Mount Mekter, on either side of the usually dry Wadi Aïn Sefra....
  • Aïn Temouchent (Algeria)
    town, northwestern Algeria, on the right bank of the Wadi Sennêne. The town is bounded on the south by the Wadi Temouchent, with the Tessala Mountains in the background. Built on the site of the ruined Roman Albula and the later Arab settlement of Ksar ibn Senar, the town was founded in 1851 with the arrival of Spanish immigrants. It lies in a narrow valley and is surrounded by vineyards an...
  • “Āīn-e Akbarī” (work by Abu ʾl-Faḍl)
    ...achievement was a history of Akbar and his ancestors, Akbar-nāmeh (Eng. trans. by H. Beveridge, The Akbarnāma of Abu-l-Faẓl, 1907–39), concluded by the Āīn-e Akbarī (Eng. trans. by H.F. Blochmann and H.S. Jarrett, ʿAin-i-Ākbari of Abul Fazl-i-ʿĀllami, 1927–49). Āīn-e....
  •  ʿAin-i-Ākbari of Abul Fazl-i-ʿĀllami (work by Abu ʾl-Faḍl)
    ...achievement was a history of Akbar and his ancestors, Akbar-nāmeh (Eng. trans. by H. Beveridge, The Akbarnāma of Abu-l-Faẓl, 1907–39), concluded by the Āīn-e Akbarī (Eng. trans. by H.F. Blochmann and H.S. Jarrett, ʿAin-i-Ākbari of Abul Fazl-i-ʿĀllami, 1927–49). Āīn-e....
  • ainame (fish)
    ...mackerel (Pleurogrammus monopterygius), a banded, black and yellow fish valued for food and sport; the lingcod (Ophiodon elongatus), a large, predatory North Pacific species; and the ainame (Hexagrammos otakii), a common food fish of Japan....
  • Aîné, L’ (French musician and composer)
    musician and composer, an outstanding member of a large and important family of musicians long connected with the French court....
  • Ainoid (people)
    ...prehistoric population of the region appears to have consisted of people who bred pigs and horses; known as Tungids, they occupied much of northeastern Asia. Stone Age fishermen, the Sibirids and Ainoids, lived along the rivers and coast....
  • Ainsworth, Henry (British theologian)
    Nonconformist theologian, Hebrew scholar, and a leader of the English Separatist colony in Amsterdam....
  • Ainsworth, William Harrison (British author)
    English author of popular historical romances....
  • Ainu (people)
    indigenous people of Hokkaido, Sakhalin, and the Kuril Islands who were culturally and physically distinct from their Japanese neighbours until the second part of the 20th century. The Ainu may be descendants of an indigenous population once widely spread over northern Asia; many contemporary Ainu claim some connection to Japan’s preh...
  • Ainu language
    ...Ainu may be descendants of an indigenous population once widely spread over northern Asia; many contemporary Ainu claim some connection to Japan’s prehistoric Jōmon culture. The traditional Ainu language, an isolate with a number of dialects, had been almost completely supplanted by Japanese by the early 21st century; a language-revitalization movement initiated formal instruction...
  • Aiora (Greek festival)
    ...Icarius, Erigone, and Maera were set among the stars as Boötes (or Arcturus), Virgo, and Procyon (Canis Minor, the Lesser Dog); to propitiate Icarius and Erigone, the festival called Aiora (the Swing) was instituted. During this festival various small images (Latin oscilla) were swung from trees, and offerings of fruit were made....
  • AIP (pathology)
    Eight different porphyrias have been identified. One common form is acute intermittent porphyria, which is caused by a deficiency of the enzyme porphobilinogen deaminase. Symptoms usually arise during adolescence, and hormonal changes (e.g., menstruation), alcohol ingestion, certain foods, and some drugs may exacerbate the condition. Diagnosis is made by detecting porphyrins in the urine.......
  • air (surfing maneuver)
    ...the board along the top of a breaking wave), “reverses” (rapid changes of direction), 360s (turning the board through 360 degrees on the face of the wave), and “airs” (flying above the face of the wave)....
  • air (atmospheric gas)
    mixture of gases comprising the Earth’s atmosphere. The mixture contains a group of gases of nearly constant concentrations and a group with concentrations that are variable in both space and time. The atmospheric gases of steady concentration (and their proportions in percentage by volume) are as follows:...
  • air (music)
    genre of solo song with lute accompaniment that flourished in England in the late 16th and early 17th centuries. The outstanding composers in the genre were the poet and composer Thomas Campion and the lutenist John Dowland, whose Flow, my teares (Lachrimae) became so popul...
  • air academy
    schools for the education and training of officers for the armed forces. Their origins date from the late 17th century, when European countries began developing permanent national armies and navies and needed trained officers for them—though the founding of academies themselves did not begin until the mid-18th century and later. Until the 20th century, training emphasized the handling of we...
  • Air America (American company)
    In 1946 Chennault returned to China to establish a commercial airline. Two years later Civil Air Transport (CAT) was founded and soon became active in the country’s civil war, transporting munitions and troops for the Nationalist government. It also did work for the U.S. Central Intelligence Agency (CIA) and was eventually bought by the organization after the communists took control of Chin...
  • air and variations (music)
    basic music technique consisting of changing the music melodically, harmonically, or contrapuntally. The simplest variation type is the variation set. In this form of composition, two or more sections are based on the same musical material, which is treated with different variational techniques in each section....
  • Air Atlanta Icelandic (Icelandic company)
    ...important internally in compensating for the limited road system. Keflavík International Airport, the country’s primary gateway, is located about 30 miles (48 km) west of Reykjavík. Air Atlanta Icelandic, a large charter airline, is active worldwide in charter operations, particularly in flying Muslim pilgrims to Mecca from various communities in Africa and the Middle East....
  • air bag (restraint system)
    ...but it took nearly two decades to establish the design and manufacturing infrastructure needed for their commercial development. One of the first products with a large market was the automobile air-bag controller, which combines inertia sensors to detect a crash and electronic control circuitry to deploy the air bag in response. Another early application for MEMS was in inkjet printheads.......
  • air base (military)
    ...technology of movement, especially by air and sea. During the 1950s the proponents of naval and land-based air power debated the relative cost and effectiveness of naval-carrier forces and fixed air bases as a tool of emergency intervention. Studies seemed to show that the fixed bases were cheaper if all related costs were considered but that the advantage of mobility and flexibility lay......
  • air bladder (fish anatomy)
    buoyancy organ possessed by most bony fish. The swim bladder is located in the body cavity and is derived from an outpocketing of the digestive tube. It contains gas (usually oxygen) and functions as a hydrostatic, or ballast, organ, enabling the fish to maintain its depth without floating upward or sinking. It also serves as a resonating chamber to produce or receive sound. In some species the sw...
  • air brake
    either of two kinds of braking systems. The first, used by railroad trains, trucks, and buses, operates by a piston driven by compressed air from reservoirs connected to brake cylinders. When air pressure in the brake pipe is reduced, air is automatically admitted into the brake cylinder. The first practical air brake for railroads was invented by George Westinghouse in the 186...
  • Air Canada (Canadian airline)
    airline established by the Canadian Parliament in the Trans-Canada Air Lines Act of April 10, 1937. Known for almost 28 years as Trans-Canada Air Lines, it assumed its current name on January 1, 1965. Air Canada’s headquarters are in Montreal....
  • air cavity (stringed musical instrument part)
    The air cavity of a string instrument, such as the violin or guitar, functions acoustically as a Helmholtz-type resonator, reinforcing frequencies near the bottom of the instrument’s range and thereby giving the tone of the instrument more strength in its low range. The acoustic band-pass filter shown in Figure 3D uses a Helmholtz resonator to absorb......
  • air chilling (food processing)
    Air chilling is the standard in Europe. The carcasses are hung by shackles and moved through coolers with rapidly moving air. The process is less energy-efficient than water chilling, and the birds lose weight because of dehydration. Air chilling prevents cross-contamination between birds. However, if a single bird contains a high number of pathogens, this pathogen count will remain on the......
  • Air Commerce Act (United States [1926])
    ...a considerable clientele, the Post Office yielded to congressional pressures and, with the Contract Air Mail Act of 1925, turned over the mail service to private contractors. The following year, the Air Commerce Act established a bureau to enforce procedures for the licensing of aircraft, engines, pilots, and other personnel. The former act stimulated design and production of advanced planes to...
  • air compressor
    device for increasing the pressure of a gas by mechanically decreasing its volume. Air is the most frequently compressed gas but natural gas, oxygen, nitrogen, and other industrially important gases are also compressed. The three general types of compressors are positive displacement, centrifugal, and axial. Positive displacement compressors are usually of the reciprocating piston type, in which ...
  • air conditioning
    the control of temperature, humidity, purity, and motion of air in an enclosed space, independent of outside conditions....
  • air conduction (sound reception)
    The outer ear directs sound waves from the external environment to the tympanic membrane (Figure 1). The auricle, the visible portion of the outer ear, collects sound waves and, with the concha, the cavity at the entrance to the external auditory canal, helps to funnel sound into the canal. Because of its small size and virtual immobility, the auricle in humans is less useful in sound gathering......
  • air cooling (technology)
    ...producing one-half of West Germany’s motor vehicles and had established a strong position in the world market. Breaking away from what had become standard design, the Volkswagen used a four-cylinder air-cooled engine at the rear of the car. It also dispensed with the annual model change that had become customary with other automobile manufacturers. Although the company had been founded b...
  • air cooling (food preservation)
    ...over a stack of packages to precool the contents. The vacuum cooling process produces rapid evaporation of a small quantity of water, lowering the temperature of the crop to the desired level. Air cooling involves the exposure of vegetables to cold air; the air must be as cold as possible for rapid cooling but not low enough to freeze the produce exposed to the direct air blast....
  • air curing (preservation process)
    ...types. Curing entails four essential steps: wilting, yellowing, colouring, and drying. These involve physical and chemical changes in the leaf and are regulated to develop the desired properties. Air curing is accomplished mainly by mechanical ventilation inside buildings. Coke, charcoal, or liquid petroleum gas may be burned to provide heat when conditions warrant. Air curing, which requires.....
  • air cushion (restraint system)
    ...but it took nearly two decades to establish the design and manufacturing infrastructure needed for their commercial development. One of the first products with a large market was the automobile air-bag controller, which combines inertia sensors to detect a crash and electronic control circuitry to deploy the air bag in response. Another early application for MEMS was in inkjet printheads.......
  • air de cour (music)
    (French: “court air”), genre of French solo or part-song predominant from the late 16th century through the 17th century. It originated in arrangements, for voice and lute, of popular chansons (secular part-songs) written in a light chordal style. Such arrangements were originally known as vau- (or voix-) de-villes (“town voice”), the name air d...
  • air division (military unit)
    ...squadrons make up a wing. (An intermediate unit between the squadron and the wing is the air group or group, which consists of two to four squadrons.) Several wings are sometimes combined to form an air division or an air force....
  • air drill (tool)
    The invention of mechanical drills powered by compressed air (pneumatic hammers) increased markedly the capability to mine hard rock, decreasing the cost and time for excavation by severalfold. It is reported that the Englishman Richard Trevithick invented a rotary steam-driven drill in 1813. Mechanical piston drills utilizing attached bits on drill rods and moving up and down like a piston in......
  • air duct (tube)
    ...in the design of air-handling systems. In order to attenuate the level of sound from blower motors and other sources of vibration, regions of larger or smaller cross-sectional area are inserted into air ducts, as illustrated in Figure 3. The impedance mismatch introduced into a duct by a change in the area of the duct or by the addition of a side branch reflects undesirable frequencies, as......
  • air embolism (medical disorder)
    blockage of an artery or vein by an air bubble. Air can be introduced into the blood vessels during surgery or traumatic accidents. One type of traumatic embolization occurs when lung tissue is ruptured; bubbles of air pass from the alveoli (air sacs) of the lungs into nearby capillaries and veins. The air bubbles are then carried into the heart, where, if trapped, they can cause myocardi...
  • air engine (mechanics)
    The air engine is thought to have originated with a 17th-century German physicist, Otto von Guericke. Guericke invented an air pump and was probably the first to make metal pistons, cylinders, and connecting rods, the basic components of the reciprocating engine. In the 17th century a Dutch inventor, Christiaan Huygens, produced an engine that......
  • air force
    that military organization of a nation which is primarily responsible for the conduct of air warfare. The air force has the missions of gaining control of the air, supporting surface forces (as by bombing and strafing), and accomplishing strategic-bombing objectives. The basic weapon systems of air forces are such military airplanes as fighters, bombers, fighter-bombers, attack aircraft, reconnais...
  • Air Force Academy, United States (academy, Colorado, United States)
    institution of higher education for the training of commissioned officers for the U.S. Air Force. It was created by act of Congress on April 1, 1954, formally opened on July 11, 1955, at temporary quarters at Lowry Air Force Base, Denver, Colo., and transferred to a permanent site 7 miles (11 km) north of Colorado Springs, Colo., in the latter part of 1958. This academy occupies an 18,000-acre (7...
  • Air Force One (American aircraft)
    institution of higher education for the training of commissioned officers for the U.S. Air Force. It was created by act of Congress on April 1, 1954, formally opened on July 11, 1955, at temporary quarters at Lowry Air Force Base, Denver, Colo., and transferred to a permanent site 7 miles (11 km) north of Colorado Springs, Colo., in the latter part of 1958. This academy occupies an 18,000-acre (7...
  • Air Force, United States (United States military)
    one of the major components of the United States armed forces, with primary responsibility for air warfare, air defense, and the development of military space research. The Air Force also provides air services in coordination with the other military branches....
  • Air France (French airline)
    French international airline originally formed in 1933 and today serving all parts of the globe. With British Airways, it was the first to fly the supersonic Concorde. Headquarters are in Paris....
  • Air France-KLM (French-Dutch airline)
    ...and, after the French government agreed to relinquish majority ownership in Air France, a privatization program was launched in 2002. In 2004 Air France acquired the Dutch airline KLM to create Air France-KLM, one of the largest air carriers in the world. The deal, however, allowed the two airlines to continue to operate as separate companies, retaining their own hubs, flights, and logos....
  • air front (meteorology)
    in meteorology, interface or transition zone between two air masses of different density and temperature; the sporadic flareups of weather along this zone, with occasional thunderstorms and electrical activity, was, to the Norwegian meteorologists who gave it its name during World War I, analogous to the fighting along the battle line in Europe. Frontal zones are frequently acco...
  • air gauge (measurement instrument)
    ...movement of a gauging spindle deflects a pointer on a graduated dial; wiggler indicators, which are used by machinists to centre or align work in machine tools; comparators, or visual gauges; and air gauges, which are used to gauge holes of various types. Very precise measurements may also be obtained by the use of light-wave interference, but the instruments that do so are referred to as......
  • air group (military unit)
    ...and often of the same model—e.g., F-16s. Three to six flying squadrons and their support squadrons make up a wing. (An intermediate unit between the squadron and the wing is the air group or group, which consists of two to four squadrons.) Several wings are sometimes combined to form an air division or an air force....
  • air gun (weapon)
    weapon based on the principle of the primitive blowgun that shoots bullets, pellets, or darts by expansion of compressed air....
  • air hoist (tool)
    Portable tools also include chipping hammers and air hoists. Pneumatic chipping hammers contain an air-operated piston that delivers successive blows to a chisel or forming tool at the end of the hammer. The valve type of tool has a separate mechanism to control the airflow to the piston, thus allowing the operator to control the speed and force of the blows. In a compression riveter the......
  • Air India (Indian airline)
    airline founded in 1932 (as Tata Airlines) that grew into an international airline owned by the Indian government; it serves southern and east Asia, the Middle East, Europe, Africa, the United States, and Canada. Headquarters are in Bombay (Mumbai)....
  • Air India Flight 182 disaster
    passenger jet explosion off the coast of Ireland on June 23, 1985, that claimed the lives of all 329 passengers and crew members. Sikh extremists were accused of sabotaging the Air India aircraft, and one suspect was convicted in 2003....
  • Air Jordan (American athlete)
    American collegiate and professional basketball player, widely considered to be the greatest all-around player in the history of the game. He led the National Basketball Association (NBA) Chicago Bulls to six championships (1991–93, 1996–98)....
  • Air Lanka (Sri Lankan airline)
    Air Lanka, the national airline, operates regularly between its base at Colombo and several major cities in Asia and Europe. Other airlines that frequent Colombo include the national carriers of Singapore, Thailand, India, The Netherlands, and Britain. The seaport of Colombo handles the bulk of Sri Lanka’s shipping, including some transshipments of the Indian ports. International cargo is a...
  • air law
    the body of law directly or indirectly concerned with civil aviation. Aviation in this context extends to both heavier-than-air and lighter-than-air aircraft. Air-cushion vehicles are not regarded as aircraft by the International Civil Aviation Organization (ICAO), but the practice of individual states in this regard is not yet settled. The earliest legislation in air law was a ...
  • air layering (horticulture)
    ...ground and covered with moist soil of good quality. When roots have developed, which may require a year or more, the branch is severed from the parent and transplanted. In an alternative technique, air layering, the branch is deeply slit and the wound covered by a ball of earth, moss, or similar material. The ball, enclosed in a divided pot supported from underneath, or in a sturdy paper cone,....
  • air leavening
    Angel food cakes, sponge cakes, and similar products are customarily prepared without either yeast or chemical leaveners. Instead, they are leavened by air entrapped in the product through vigorous beating. This method requires a readily foaming ingredient capable of retaining the air bubbles, such as egg whites. To produce a cake of fine and uniform internal structure, the pockets of air......
  • air lift pump
    Other types of pumps. Gas lifts are used to raise liquids from the bottoms of wells. Compressed gas is introduced into the liquid near the bottom of the well as in Figure 6. The resulting mixture of gas and liquid is lighter and more buoyant than the liquid alone so that the mixture rises and is discharged. Gas lifts have no moving parts, and they can be used to pump liquids containing......
  • air lock
    device that permits passage between regions of differing air pressures, most often used for passage between atmospheric pressure and chambers in which the air is compressed, such as pneumatic caissons and underwater tunnels. The air lock also has been used as a design feature of space vehicles; on March 18, 1965, the Soviet cosmonaut Aleksey Leonov...
  • air mail
    letters and parcels transported by airplanes. Airmail service was initiated in 1911 in England between Hendon (northwest of London) and Windsor, to celebrate the coronation of George V. Service was irregular, however, and only 21 trips were made. Continuous regular air transport of letters between London and Paris was established in 1919, and a similar service for parcels in 19...
  • Air Malaŵi (Malaŵi airline)
    Air Malaŵi, the national airline, operates services from the main airport at Chileka, 11 miles from Blantyre, to several foreign countries and neighbouring African capitals....
  • air mass (meteorology)
    in meteorology, large body of air having nearly uniform conditions of temperature and humidity at any given level of altitude. Such a mass has distinct boundaries and may extend hundreds or thousands of kilometres horizontally and sometimes as high as the top of the troposphere (about 10–18 km [6–11 miles] above the Earth’s surface). An air mass forms whenever the atmosphere r...
  • Aïr massif (mountains, Niger)
    group of granitic mountains rising sharply from the Sahara in central Niger. Several of these mountains approach and exceed 6,000 feet (1,800 m), the highest being Mount Gréboun (6,378 feet [1,944 m]). The mountains are dissected by deep valleys, called koris, in which some vegetation permits the pasturage of livestock, owned mainly by Tuaregs. Hot springs are foun...
  • Air New Zealand Limited (New Zealand airline)
    New Zealand international airline founded in 1939 (as Tasman Empire Airways Limited, or TEAL) and, by 1980, operating throughout the South Pacific from New Zealand and Australia to Hong Kong and Singapore and to Tahiti, Hawaii, and Los Angeles. The original shareholders in 1939 were New Zealand (50 percent), Australia (30 percent), and Britain (20 percent); Britain withdrew in 1953, and New Zealan...
  • air pilot (aeronautics)
    ...continue underneath. The economics of air travel require relatively long-distance travel from origin to destination in order to retain economic viability. For the vehicle operator (i.e., the pilot), this means short periods of high concentration and stress (takeoffs and landings) with relatively long periods of low activity and arousal. During this long-haul portion of a flight, a pilot....
  • air plant (plant species)
    The most common species, valued for their unusual foliage, include the panda plant (K. tomentosa); penwiper plant (K. marmorata); air plant, or maternity plant (K. pinnata); velvet leaf, or felt bush (K. beharensis); devil’s backbone (K. daigremontiana); and South American air plant (K. fedtschenkoi). A range of attractive pot plants, distinguished ...
  • air plant (plant type)
    any plant that grows upon or is in some manner attached to another plant or object merely for physical support. Epiphytes are primarily tropical in distribution and are often known as air plants because they have no attachment to the ground or other obvious nutrient source. They obtain water and minerals from rain and also from debris that collects on the supporting plants. Orchids, ferns, and mem...
  • air pocket (meteorology and aviation)
    strong updraft or downdraft encountered by an aircraft in flight. See updraft and downdraft....
  • air pollution
    Air pollution involves the release into the atmosphere of gases, finely divided solids, or finely dispersed liquid aerosols at rates that exceed the capacity of the atmosphere to dissipate them or to dispose of them through incorporation into solid or liquid layers of the biosphere. Air pollution results from a variety of causes, not all of which are within human control. Dust storms in desert......
  • air potato (yam)
    ...is a winged capsule or a berry. Several species of yams (vines of the genus Dioscorea) are grown for their edible tuberous roots, such as Chinese yam, or cinnamon vine (D. batatas); air potato (D. bulbifera); and yampee, or cush-cush (D. trifida)....
  • air 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 mercury that exactly balances the weight of the column of atmosphere over the...
  • air pump (engineering)
    German physicist, engineer, and natural philosopher who invented the first air pump and used it to study the phenomenon of vacuum and the role of air in combustion and respiration....
  • air purifier (device)
    German physicist, engineer, and natural philosopher who invented the first air pump and used it to study the phenomenon of vacuum and the role of air in combustion and respiration.......
  • air quality
    Air pollution involves the release into the atmosphere of gases, finely divided solids, or finely dispersed liquid aerosols at rates that exceed the capacity of the atmosphere to dissipate them or to dispose of them through incorporation into solid or liquid layers of the biosphere. Air pollution results from a variety of causes, not all of which are within human control. Dust storms in desert......
  • air racing (sport)
    sport of racing airplanes, either over a predetermined course or cross-country up to transcontinental limits. Air racing dates back to 1909, when the first international meet was held at Reims, France....
  • air resistance (atmospheric gas)
    mixture of gases comprising the Earth’s atmosphere. The mixture contains a group of gases of nearly constant concentrations and a group with concentrations that are variable in both space and time. The atmospheric gases of steady concentration (and their proportions in percentage by volume) are as follows:...
  • air route surveillance radar (radar technology)
    ...by radio direction-finding equipment. The radio technologies are able to transmit the heading and distance to an intended destination. These aircraft-mounted technologies are supplemented by air route surveillance radar, which monitors aircraft within each designated sector of the air route traffic control system. The radar-based systems form the backbone of the navigation aids for......
  • air sac (anatomy)
    any of the air-filled extensions of the breathing apparatus of many animals. Air sacs are found as tiny sacs off the larger breathing tubes (tracheae) of insects, as extensions of the lungs in birds, and as end organs in the lungs of certain other vertebrates. They serve to increase respiratory efficiency by providing a large surface area for gas exchange. See also ...
  • Air, School of the (school, Australia)
    ...Track, Meekatharra now receives livestock trucked south down the Great Northern Highway from as far away as Broome. Meekatharra is the site of a Royal Flying Doctor Service and the first regular School of the Air (public education by radio for outback children). The town is also a base for mining in the region. The name Meekatharra is said to derive from an Aboriginal term for “bad......
  • air seasoning (wood treatment)
    ...is subject to attack by fungi and insects, and it also shrinks as it dries. Because it does not shrink evenly in all directions, it is likely to split and warp. The most common seasoning methods are air seasoning and dry-kiln seasoning. In air seasoning, the boards are stacked and divided by narrow pieces of wood called stickers so that the air can circulate freely about each board. The stack i...
  • air show (sport)
    Another venue for stunt pilots was the air show. At such programs the crowd would be entertained with aerial feats. For instance, stunt pilot Milo Burcham (d. 1944), a master of crazy flying, performed a routine in which he would lose a wheel on take off and frantically attempt to land without it. (There was another wheel too small for the crowd to see that actually permitted him to land.)......
  • air shower (physics)
    ...the positions of nearby active galaxies that contain black holes millions of times the mass of the Sun. These extremely high-energy particles are so rare that they can be detected only through the extensive air showers (EAS) that they produce in the atmosphere. An extensive air shower may consist of billions of secondaries (mostly electrons and muons) that arrive at ground level over areas of.....
  • Air Southwest Company (American corporation)
    American airline incorporated in 1967 as Air Southwest Company. The current name was adopted in 1971. The company features low-fare, no-frills air service with frequent flights of mostly short routes. Costs are kept down by the exclusive use of Boeing 737 aircraft, which allows for low maintenance costs and quicker turnaround times for flights, and by an emphasis on ticketless travel. Headquarter...
  • air space (plant leaf)
    ...like irregular paving stones, continue to expand in the plane of the leaf after growth ceases in the mesophyll, so that the cells of the internal tissues are pulled apart to form the system of air spaces found in the mature leaf....
  • air space (air law)
    in international law, the space above a particular national territory, treated as belonging to the government controlling the territory. It does not include outer space, which, under the Outer Space Treaty of 1967, is declared to be free and not subject to national appropriation. The treaty, however, did not define the altitude at which outer space begins and air space ends. ...
  • air spring (mechanics)
    load-carrying component of an air suspension system used on machines, automobiles, and buses. A system used on buses consists of an air compressor, an air-supply tank, leveling valves, check valves, bellows, and connecting piping. Basically, an air-spring bellows is a column of air confined within a rubber and fabric container that looks like an automobile tire or two or three tires stacked on to...
  • air staff (military science)
    ...not trained as an elite corps; they were individually selected from the officer corps as a whole just as for other assignments. The air force counterpart of army general staff is usually called the air staff....
  • air superiority fighter (aircraft)
    ...navigating in unfamiliar or hostile territory at night. A day fighter is an airplane in which weight and space are saved by eliminating the special navigational equipment of the night fighter. The air supremacy, or air superiority, fighter must have long-range capability, to enable it to travel deep into enemy territory to seek out and destroy enemy fighters. Fighter-bombers fill the dual role....
  • air supremacy fighter (aircraft)
    ...navigating in unfamiliar or hostile territory at night. A day fighter is an airplane in which weight and space are saved by eliminating the special navigational equipment of the night fighter. The air supremacy, or air superiority, fighter must have long-range capability, to enable it to travel deep into enemy territory to seek out and destroy enemy fighters. Fighter-bombers fill the dual role....
  • air suspension (mechanics)
    Air suspensions were introduced in 1953 and continue to be employed on integral-frame bus models. They consist of multiple heavy rubber bellows, or air springs, mounted at each axle. The air springs are supplied with air from a reservoir in which the pressure is maintained at about 690 kilopascals (100 pounds per square inch). An advantage gained from this type of suspension is that, as the......
  • air temperature
    the phenomenon of increasing average air temperatures near the surface of Earth over the past one to two centuries. Since the mid-20th century, climate scientists have gathered detailed observations of various weather phenomena (such as temperature, precipitation, and storms) and of related influences on climate (such as ocean currents and the atmosphere’s chemical composition). These data....
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