air force Military organization that has the primary responsibility for conducting air warfare. The air force must gain control of the air, support ground forces (e.g., by attacking enemy ground forces), and accomplish strategic-bombing objectives. Its basic weapons platforms are fighters, bombers, attack aircraft, and early warning and control aircraft. Since the mid-20th century, some air forces have also been responsible for land- based nuclear missiles as well as nuclear-armed bombers. The army and naval branches of a state’s armed forces may also operate aircraft.
Air France in full Compagnie Internationale Air France
French passenger and cargo airline with more than 200 destinations in some 80 countries. It introduced supersonic Concorde service in 1976, but financial loss led the company to cease its Concorde operations in 2003. The French government began privatizing the former national air¬ line in July 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 two airlines, however, continued to operate as separate companies, retain¬ ing their own hubs, flights, and logos.
air mass In meteorology, a large body of air having nearly uniform conditions of temperature and humidity at any given altitude. Such a mass has distinct boundaries and may extend hundreds or thousands of miles horizontally and sometimes as high as the top of the troposphere. An air mass forms whenever the atmosphere remains in contact with a large, relatively uniform land or sea surface long enough to acquire its tempera¬ ture and moisture properties. The Earth’s major air masses all originate in polar or subtropical latitudes. The middle latitudes constitute essen¬ tially a zone of modification, interaction, and mixing of the polar and tropical air masses.
air pollution Release into the atmosphere of gases, finely divided sol¬ ids, or finely dispersed liquid aerosols at rates that exceed the capacity of the atmosphere to dissipate them or to dispose of them through incorpo¬ ration into the biosphere. Dust storms in desert areas and smoke from for¬ est and grass fires contribute to particulate and chemical air pollution. Volcanic activity is the major natural source of air pollution, pouring huge amounts of ash and toxic fumes into the atmosphere. Air pollution may affect humans directly, causing irritation of the eyes or coughing. More indirectly, its effects can be measured far from the source, as, for example, the fallout of tetraethyl lead from automobile exhausts, which has been observed in the oceans and on the Greenland ice sheet. Still less direct are possible effects on global climates. See also smog.
air warfare Military operations conducted by airplanes, helicopters, or other aircraft against aircraft or targets on the ground and in the water. Air warfare did not become important until World War I (1914-18). The British, French, German, Russian, and Italian armed forces had flying units, including biplanes armed with machine guns for “dogfights” with enemy fighter aircraft. Zeppelins and larger airplanes carried out bombing raids. The 1920s and ’30s saw the development of the monoplane, the all-metal fuselage, and the aircraft carrier. During World War II (1939— 45), the Battle of Britain was the first fought exclusively in the air, the Battle of the Coral Sea was the first between carrier-based aircraft, and the atomic bombings of Hiroshima and Nagasaki were the first use of
Ainu \'I-nii\ Indigenous people of what is now Japan. Pushed north by the Japanese people over the last 2,000 years, the few remaining pure Ainu today live principally in northern Hokkaido, Sakhalin, and the Kuril Islands. Once physically and cultur¬ ally distinct from the Japanese, their origins and their role in Japanese his¬ tory and prehistory have been the subject of scholarly debate. Many contemporary Ainu claim some con¬ nection to the prehistoric Jomon cul¬ ture. The Ainu language, which has no known relationship to any other language, is virtually extinct, being supplanted by Japanese. The Ainu were traditionally hunters, fisher¬ men, and trappers; their religion cen¬ tred on spirits believed to be present in animals and the natural world.
air Mixture of gases constituting the earth’s atmosphere. Some gases occur in steady concentrations. The most important are molecular nitro¬ gen (N 2 ), 78% by volume, and molecular oxygen (0 2 ), 21%. Small amounts of argon (Ar; 1.9%), neon (Ne), helium (He), methane (CH 4 ), krypton (Kr), hydrogen (H 2 ), nitrous oxide (N 2 0), and xenon (Xe) are also present in almost constant propor¬ tions. Other gases occur in variable concentrations: water vapour (H 2 0), ozone (0 3 ), carbon dioxide (C0 2 ), sulfur dioxide (S0 2 ), and nitrogen dioxide (N0 2 ). Air also contains trace amounts of ammonia and hydro¬ gen sulfide. The variable constituents are important for maintaining life. Water vapour is the source for all forms of precipitation and is an impor¬ tant absorber and emitter of infrared radiation. Carbon dioxide is neces¬ sary for photosynthesis and is also an important absorber and emitter of infrared radiation. Ozone in the stratosphere (see ozone layer) is an effec¬ tive absorber of ultraviolet radiation from the Sun but at ground-level is a corrosive pollutant and a major constituent of smog.
Ainu couple in ceremonial dress, Hok¬ kaido, Japan.
COURTESY OF THE CONSULATE GENERAL OF JAPAN, NEW YORK CITY
Ailly \a-'ye\, Pierre d' (b. 1350,
Compiegne, Fr.—d. Aug. 9, 1420,
Avignon) French theologian and car¬ dinal. D’Ailly worked to end the Western Schism. He advocated the doctrine of conciliarism (see Con¬ ciliar Movement), which maintained that supreme authority in the church was held by a general council. He was active at the Council of Pisa (1409), which deposed both pope and antipope in favour of the new conciliar pope, Alexander V, but failed to end the schism. He was also involved in the Council of Constance (1414-18), which called for the abdication of the antipope John XXIII (r. 1410-15) and the election of another pope (Martin V) and ended the schism. His writings included a geographical treatise. Image of the World , used by Christopher Columbus.
Alvin Ailey, Jr., 1960.
COURTESY OF ZACHARY FREYMAN
© 2006 Encyclopaedia Britannica, Inc.
airbrush ► airship I 33
nuclear-armed bombers. In the jet age, air power has continued to be used in strategic bombing of an enemy’s home territory (as in the Vietnam War, 1965-74), destroying enemy air forces (as in the Arab-Israeli wars), attacking and defending carrier-based naval fleets (as in the Falkland Islands War, 1982), and supporting ground forces (as in the Persian Gulf War, 1990-91).
airbrush Pneumatic device for developing a fine, small-diameter spray of paint, protective coating, or liquid colour (see aerosol). The airbrush can be a pencil-shaped atomizer used for various highly detailed activities such as shading drawings and retouching photographs; in contrast, a spray gun is usually used for covering large surfaces with paint.
Airbus S.A.S. European aircraft manufacturer that is the world’s sec¬ ond largest maker of commercial aircraft (after Boeing Co.). It is co-owned by the German-French-Spanish European Aeronautic Defence and Space Company (EADS), with an 80% interest, and Britain’s BAE Systems, with 20%. Airbus was formed as a consortium in 1970 by French and German aerospace firms (later joined by Spanish and British companies) to fill a market niche for short- to medium-range, high-capacity jetliners and to compete with long-established American manufacturers. Its first product, the A300, entered service in 1974. It was the first wide-body jetliner equipped with only two engines for more economical operation. The twin- engine A320 (entered service 1988) incorporated numerous technical innovations, notably fly-by-wire (electric rather than mechanically linked), computer-based flight controls. The four-engine A340 (1993) and smaller, twin-engine A330 (1994) were long-range airliners. In 2000 Air¬ bus launched development of the A380, intended to be the world’s larg¬ est passenger jet with a typical seating of 555 people. The consortium integrated into a single company in 2001.