(from Greek geo, earth, graphein, to write), the scientific study of the Earth's surface. Geography describes and analyzes the spatial variations in physical, biological, and human phenomena that occur on the surface of the globe and treats their interrelationships and their significant regional patterns. Geography is one of the oldest subjects of study, and it has been called the mother of sciences. In the classical world geography had close ties with history (as in Herodotus) in attempting to describe what other lands and peoples were like or with astronomy and philosophy (as in Eratosthenes and Ptolemy) in trying to ascertain the size of the Earth and to locate places on it. Alexander von Humboldt (17691859), a German naturalist and geographer, was a key figure in the rise of modern geography because of his exact measurements, his careful recording of observations, and his mapping of significant areal patterns of human and natural features. Though once associated entirely with mapping and the exploration of the Earth, the discipline of geography is today a wide-ranging one. Any pattern of spatial variation of phenomena on the surface of the Earth may be influenced by many of the processes that animate the natural and human realms, requiring geographers to be conversant with the principles of the biological, social, and earth sciences. Desertification in Africa, for example, is often attributed to drought, but studies reveal that it has been accelerated by overgrazing, overexpansion of farming, and removal of trees and shrubs for firewood. Many such phenomena are studied by other specialists, but it is the distinctive task of the geographer to investigate their distributional patterns, their regional complexes, the networks that link the elements, and the processes involved in the interaction among them. The special subdisciplines of geography are divided into areas of physical, human, and regional geography. Physical geography is further subdivided into geomorphology, climatology, biogeography, and hydrology. In this category particular attention has been paid to coastal areas, to water and mineral resources (including energy), and to natural hazards. Human geography includes historical geography, cultural and social geography, population geography, political geography, economic geography (including the study of agriculture, industry, trade, and transportation), and urban geography. Medical geography, environmental management, and conservation of resources fall between these two large fields. The scale of study in regional geography may range from worldwide regionalization, to a continent, a major cultural area, a country, a subregion within a country, or a city. Geography utilizes a battery of methods and techniques. Particularly important are direct field observations and mapping. Methods of observation have been enhanced by such means as aerial photography and electronic remote sensing from artificial Earth satellites. Statistical methods help in spatial analysis of quantitative data, particularly census and survey data. Maps, however, remain the distinctive tool for the geographer. The discipline of geography has many uses. It enables individuals to know the basic features of the world in which they live, the great variety of lands and peoples, the complex associations and interrelations of human beings with resources and nature, and the problems faced by inhabitants of other countries and regions. Geographic research provides explanations of the distribution of physical, biological, and human features on Earth and of their complex chains of interconnection. Applied geographic analysis has proved useful in managing resources, in understanding problems of the environment, in analyzing natural hazards (such as droughts or floods), and in measuring the distribution of environmental pollution or contamination by discharges of urban, agricultural, and industrial wastes. The analysis of unanticipated environmental effects caused by the construction of large dams and reservoirs has been particularly important. Geographers are engaged in planning land use and housing. They are an important resource in national and international agencies that deal with the study, inventory, development, or administration of natural or human resources. the study of the surface of the Earth. The word is derived from the Greek words geo (the Earth) and graphein (to write). The surface of the Earth is the interface of the atmosphere, lithosphere, hydrosphere, and biosphere. It provides the habitat, or environment, in which humans are able to live. This habitable zone has a number of special characteristics. One of the most important is the complex interaction among many physical, biologic, and human elements of the Earth, such as land surface, climate, water, soil, vegetation, agriculture, and urbanization. Another characteristic is the high variability of the environment from place to placehot tropics to cold polar regions, dry deserts to humid equatorial forests, vast level plains to rugged mountains, and uninhabited ice caps to densely settled metropolitan areas. Yet another is the consistency with which significant patterns occur, which makes possible generalizations about distributions; obvious examples are measurements of temperature and rainfall, which are the most important climatic elements affecting farming and many other human activities. Geographic study is particularly concerned with location, with areal patterns, with the interrelationships of phenomena (especially of the relationship between human society and the land, as in ecology), with regionalization, and with ties among areas. Typical areas of inquiry include where people live; in what sort of patterns they are distributed over the Earth's surface; what factors of environment, resources, culture, and economic development account for this distribution; whether or not significant regions can be recognized by types of population, livelihood, and culture; and what types of movements and relations occur among places. Additional reading History of geography Preston E. James and Geoffrey J. Martin, All Possible Worlds: A History of Geographical Ideas, 2nd ed. (1981), is a general history of the rise of the discipline of geography, with emphasis on the modern period. Robert E. Dickinson and O.J.R. Howarth, The Making of Geography (1933, reprinted 1976), though dated in some respects, is still useful. George Kish (ed.), A Source Book in Geography (1978), is a handy annotated anthology. Richard Hartshorne, The Nature of Geography (1939, reprinted 1976), and Perspective on the Nature of Geography (1959, reissued 1968), provide a detailed examination of writings on the subject. J. Oliver Thomson, History of Ancient Geography (1948, reissued 1965), is a well-documented review of knowledge and theories. J.N.L. Baker, A History of Geographical Discovery and Exploration, rev. ed. (1936, reissued 1967), remains the best single-volume summary of geographic explorations. See also the valuable bibliographies in Geographers: Biobibliographical Studies (irregular). For the modern period, see, for French and German work up to the 1960s, Robert E. Dickinson, The Makers of Modern Geography (1969); on British geography, T.W. Freeman, A History of Modern British Geography (1980); on French geography, Paul Claval, La Pense gographique (1972); on Soviet geography, I.P. Gerasimov (ed.), Soviet Geography, trans. from Russian (1962); and on geography in the United States, Preston E. James and Clarence F. Jones (eds.), American Geography (1954). Developments in 11 countries or regions in the latter part of the 20th century are discussed in R.J. Johnston and Paul Claval (eds.), Geography Since the Second World War (1984). Methodology A standard introduction to cartography is Arthur H. Robinson et al., Elements of Cartography, 5th ed. (1984). Various aspects of cartography are covered in J.B. Harley and David Woodward (eds.), The History of Cartography (1987 ), an outstanding work, with one of six planned volumes published. More specialized are Phillip C. Muehrcke and Juliana O. Muehrke, Map Use: Reading, Analysis, and Interpretation, 2nd ed. (1986); and Mark S. Monmonier, Computer-Assisted Cartography: Principles and Prospects (1982). The Times Atlas of the World, 7th ed. (1985); Rand McNally, The New International Atlas (1980, reissued 1987); and National Geographic Atlas of the World, 5th ed. (1981), are all examples of excellent cartography. Aerial photography is treated in C.P. Lo, Geographical Applications of Aerial Photography (1976). Introductions to remote sensing are provided by Benjamin F. Richason, Jr. (ed.), Introduction to Remote Sensing of the Environment, 2nd ed. (1983); and Robert K. Holz (ed.), The Surveillant Science: Remote Sensing of the Environment, 2nd ed. (1985). Robert N. Colwell (ed.), Manual of Remote Sensing, 2nd ed., 2 vol. (1983), is advanced and comprehensive. Pioneering and influential volumes on quantitative methods include Torsten Hgerstrand, Innovation Diffusion as a Spatial Process (1967; originally published in Swedish, 1953), a classic study; Richard J. Chorley and Peter Haggett (eds.), Models in Geography (1967); and Peter Haggett, Andrew D. Cliff, and Allan Frey, Locational Analysis in Human Geography, 2nd ed. (1977). See also John F. Lounsbury and Frank T. Aldrich, Introduction to Geographic Field Methods and Techniques, 2nd ed. (1986). Physical geography (General) Cuchlaine A.M. King, Physical Geography (1980), provides coverage at local, regional, and continental scales. Tom L. McKnight, Physical Geography: A Landscape Appreciation, 2nd ed. (1987), is a succinct review. Arthur N. Strahler and Alan H. Strahler, Elements of Physical Geography, 3rd ed. (1984), is comprehensive and well illustrated. Michael J. Clark, Kenneth J. Gregory, and Angela M. Gornell (eds.), Horizons in Physical Geography (1987), offers overviews of issues in the field. (Geomorphology) Karl W. Butzer, Geomorphology from the Earth (1976), is generally nontechnical. B.W. Sparks, Geomorphology, 3rd ed. (1986), stresses deficiencies in theory. Arthur L. Bloom, Geomorphology: A Systematic Analysis of Late Cenozoic Landforms (1978), is a thorough introduction. Works devoted to special processes include Luna B. Leopold, M. Gordon Wolman, and John P. Miller, Fluvial Processes in Geomorphology (1964); Clifford Embleton and Cuchlaine A.M. King, Glacial and Periglacial Geomorphology, 2nd ed., 2 vol. (1975); Cuchlaine A.M. King, Beaches and Coasts, 2nd ed. (1972); and Julius Bdel, Climatic Geomorphology (1982; originally published in German, 1977). (Climatology) Nontechnical introductions include Howard J. Critchfield, General Climatology, 4th ed. (1983); John E. Oliver and John J. Hidore, Climatology (1984); Glenn T. Trewartha and Lyle H. Horn, An Introduction to Climate, 5th ed. (1980); and Roger G. Barry and Richard J. Chorley, Atmosphere, Weather, and Climate, 5th ed. (1987). A comprehensive analysis is H.E. Landsberg (ed.), World Survey of Climatology (1969 ), a multivolume series. (Biogeography) Introductions are provided by James H. Brown and Arthur C. Gibson, Biogeography (1983), with broad coverage and many references; Pierre Dansereau, Biogeography: An Ecological Perspective (1957); I.G. Simmons, Biogeography: Natural and Cultural (1979), which focuses on human influence in the biosphere; and Joy Tivy, Biogeography: A Study of Plants in the Ecosphere, 2nd ed. (1982), which includes environmental and historical influences on plant distributions. Advanced specialized studies are contained in Carl Troll (ed.), Geo-Ecology of the Mountainous Regions of the Tropical Americas (1968), and Geoecology of the High-Mountain Regions of Eurasia (1972). (Soil geography) Brief introductions to the field include Robert M. Basile, A Geography of Soils (1971); and Donald Steila, The Geography of Soils: Formation, Distribution, and Management (1976). (Resource management and environmental studies) Good general introductions, with extensive bibliographies on environmental studies, include Ian R. Manners and Marvin W. Mikesell (eds.), Perspectives on Environment (1974); and Kenneth A. Hammond, George Macinko, and Wilma B. Fairchild (eds.), Sourcebook on the Environment: A Guide to the Literature (1978). The seminal contributions of Gilbert F. White to resource management and essays on related themes are contained in Robert W. Kates and Ian Burton (eds.), Geography, Resources, and Environment, 2 vol. (1986). Other valuable works include Andrew Goudie, The Human Impact on the Natural Environment, 2nd ed. (1986); Gilbert F. White (ed.), Natural Hazards (1974); Ian Burton, Robert W. Kates, and Gilbert F. White, The Environment as Hazard (1978); Robert W. Kates, Risk Assessment of Environmental Hazard (1978); Anne V. Whyte and Ian Burton (eds.), Environmental Risk Assessment (1980); Thomas F. Saarinen, David Seamon, and James L. Sell (eds.), Environmental Perception and Behavior (1984); J.T. Coppock and B.S. Duffield, Recreation in the Countryside (1975); and Stephen Smith, Recreation Geography (1983). Human geography (General) General introductions to the field include Peter Haggett, Geography, rev. 3rd ed. (1983), emphasizing ecological and spatial approaches; Jan O.M. Broek and John W. Webb, A Geography of Mankind, 3rd ed. (1978), a cultural and economic approach; and Rhoads Murphey, Patterns on the Earth: An Introduction to Geography, 4th ed. (1978), a historical and cultural approach within a regional framework. (Population geography) A good international summary of approaches is John I. Clarke (ed.), Geography and Population (1984). Useful general reviews of the field include George A. Schnell and Mark S. Monmonier, The Study of Population (1983), with world maps showing countries scaled by population size; and Huw R. Jones, A Population Geography (1981), with an extensive bibliography. Population pressures in relation to resources and resource depletion are treated in Gary L. Peters and Robert P. Larkin, Population Geography, 2nd ed. (1983); and Wilbur Zelinsky, Leszek A. Kosnski, and R. Mansell Prothero (eds.), Geography and a Crowding World (1970), papers from a symposium on population pressures on physical and social resources in the developing lands. Population in relation to development is considered in Philip M. Hauser (ed.), World Population and Development (1979). Migration is reviewed in Leszek A. Kosnski and R. Mansell Prothero (eds.), People on the Move: Studies on Internal Migration (1975). (Economic geography) Brief introductions include Harold H. McCarty and James B. Lindberg, A Preface to Economic Geography (1966); and Robert B. McNee, A Primer on Economic Geography (1971). General treatments include Richard S. Thoman and Peter B. Corbin, The Geography of Economic Activity, 3rd ed. (1974); and James O. Wheeler and Peter O. Muller, Economic Geography, 2nd ed. (1986), with a North American orientation. Somewhat more advanced and theoretical are Brian J.L. Berry, Edgar C. Conkling, and D. Michael Ray, The Geography of Economic Systems (1976); Peter E. Lloyd and Peter Dicken, Location in Space: A Theoretical Approach to Economic Geography, 2nd ed. (1977); and Thomas J. Wilbanks, Location and Well-Being: An Introduction to Economic Geography (1980). (Cultural and social geography) General treatments include Philip L. Wagner and Marvin W. Mikesell (eds.), Readings in Cultural Geography (1962); J.E. Spencer and William L. Thomas, Introducing Cultural Geography, 2nd ed. (1978); and Terry G. Jordan and Lester Rowntree, The Human Mosaic: A Thematic Introduction to Cultural Geography, 4th ed. (1986). Two important collections of papers are William L. Thomas (ed.), Man's Role in Changing the Face of the Earth (1956, reissued in 2 vol., 1970); and John Leighly (ed.), Land and Life: A Selection from the Writings of Carl Ortwin Sauer (1963, reprinted 1974). General introductions to social geography include David Ley, A Social Geography of the City (1983); and Paul Knox, Urban Social Geography: An Introduction, 2nd ed. (1987). (Urban geography) Major works on worldwide urbanization include Brian J.L. Berry, Comparative Urbanization, rev. and enl. 2nd ed. (1981); L.S. Bourne, R. Sinclair, and K. Dziewnski (eds.), Urbanization and Settlement Systems (1984); and Stanley D. Brunn and Jack F. Williams (eds.), Cities of the World: World Regional Urban Development (1983). North American cities are treated in Truman Asa Hartshorn, Interpreting the City: An Urban Geography (1980); Stanley D. Brunn and James O. Wheeler (eds.), The American Metropolitan System (1980); Risa Palm, The Geography of American Cities (1981); Maurice Yeates and Barry Garner, The North American City, 3rd ed. (1980); and Peter O. Muller, Contemporary Suburban America (1981). Jean Gottmann, Megalopolis: The Urbanized Northeastern Seaboard of the United States (1961, reissued 1969), is a classic study. A similar study for Canada is Maurice Yeates, Main Street: Windsor to Quebec City (1975). British cities are more fully treated in Harold Carter, The Study of Urban Geography, 3rd ed. (1981); and David T. Herbert and Colin J. Thomas, Urban Geography (1982). Walter Christaller, Central Places in Southern Germany (1966; originally published in German, 1933), is a widely influential study. (Political geography) Alan D. Burnett and Peter J. Taylor (eds.), Political Studies from Spatial Perspectives: Anglo-American Essays on Political Geography (1981), is an influential collection of papers; more diverse is Peter J. Taylor and John House (eds.), Political Geography (1984). Martin Ira Glassner and Harm J. De Blij, Systematic Political Geography, 3rd ed. (1980), is a widely used text. Special topics are treated by J.R.V. Prescott, Boundaries and Frontiers (1978), and The Political Geography of the Oceans (1975); Peter J. Taylor and R.J. Johnston, The Geography of Elections (1979); and Jean Gottmann (ed.), Centre and Periphery: Spatial Variation in Politics (1980). (Medical geography) Good introductions to medical geography include Andrew T.A. Learmonth, Patterns of Disease and Hunger (1978); Gerald F. Pyle, Applied Medical Geography (1979); and the older but still valuable L. Dudley Stamp, The Geography of Life and Death (1964). Studies of infectious diseases are summarized in Jacques M. May, The Ecology of Human Disease (1958); and Jacques M. May (ed.), Studies in Disease Ecology (1961). For analyses of spatial aspects of health-care delivery systems, see John Eyles and Kevin J. Woods, The Social Geography of Medicine and Health (1983), international in scope; David R. Phillips, Contemporary Issues in the Geography of Health Care (1981), a comparison of the British and American systems; and Gary W. Shannon and G.E. Alan Dever, Health Care Delivery: Spatial Perspectives (1974), primarily American in focus. Diverse aspects are presented in the following conference papers or collected volumes: Andrew T.A. Learmonth (ed.), The Geography of Health (1981); Neil D. McGlashan and John R. Blunden (eds.), Geographical Aspects of Health (1983); Melinda S. Meade (ed.), Conceptual and Methodological Issues in Medical Geography (1980); and Gerald F. Pyle (ed.), New Directions in Medical Geography (1979). (Historical geography) An international overview of work in historical geography during the period 194570 is provided by Alan R.H. Baker (ed.), Progress in Historical Geography (1972). Research methods are discussed in Alan R.H. Baker and Mark Billinge (eds.), Period and Place: Research Methods in Historical Geography (1982); William Norton, Historical Analysis in Geography (1984); and Alan R.H. Baker and Derek Gregory (eds.), Explorations in Historical Geography (1984). H.C. Darby (ed.), A New Historical Geography of England (1973); and R.A. Dodgshon and R.A. Butlin (eds.), An Historical Geography of England and Wales (1978), are valuable summaries. D.W. Meinig, The Shaping of America: A Geographical Perspective on 500 Years of History, vol. 1, Atlantic America, 14921800 (1986), is an important synthesis. James R. Gibson (ed.), European Settlement and Development in North America (1978); and Robert D. Mitchell and Paul A. Groves (eds.), North America: The Historical Geography of a Changing Continent (1987), contain many valuable studies. See also Ronald E. Grim, Historical Geography of the United States: A Guide to Information Sources (1982), which provides admirable coverage; and R. Cole Harris and John Warkentin, Canada Before Confederation: A Study in Historical Geography (1974), which covers the early period in Canada. Prehistory is discussed in Karl W. Butzer, Environment and Archeology (1971), and Archaeology as Human Ecology (1982). Regional geography Some useful treatments covering the large regions of the world include C. Langdon White, Edwin J. Foscue, and Tom L. McKnight, Regional Geography of Anglo-America, 6th ed. (1985); J.H. Paterson and Clarence W. Olmstead, North America: A Geography of Canada and the United States, 7th ed. (1984); J. Wreford Watson, North America, 2nd ed. (1968); Studies in Canadian Geography, 6 vol. (1972); Preston E. James, C.W. Minkel, and Eileen W. James, Latin America, 5th ed. (1986); Robert C. West and John P. Augelli, Middle America, 2nd ed. (1976); George W. Hoffman (ed.), A Geography of Europe, 5th ed. (1983); Paul E. Lydolph, Geography of the U.S.S.R.: Topical Analysis (1979); R.J. Johnston and J.C. Dornkamp (eds.), The Changing Geography of the United Kingdom (1982); William A. Hance, The Geography of Modern Africa, 2nd ed. (1975); R.J. Harrison Church et al., Africa and the Islands, 4th ed. (1977); A.T. Grove, Africa, 3rd ed. (1978); W.B. Fisher, The Middle East: A Physical, Social, and Regional Geography, 7th ed. rev. (1978); Norton Ginsburg, The Pattern of Asia (1958); J.E. Spencer and William L. Thomas, Asia, East by South: A Cultural Geography, 2nd ed. (1971); O.H.K. Spate and Andrew T.A. Learmonth, India and Pakistan: A General and Regional Geography, 3rd ed. rev. (1967); and D.N. Jeans (ed.), Australia: A Geography (1977). Bibliographic guides Further bibliographic information may be found in Stephen Goddard (ed.), A Guide to Information Sources in the Geographical Sciences (1983); J. Gordon Brewer, The Literature of Geography: A Guide to Its Organisation and Use, 2nd ed. (1978), textual discussion with some emphasis on British works; and Chauncy D. Harris, Bibliography of Geography, pt. 1, Introduction to General Aids (1976), and pt. 2, Regional, vol. 1, The United States of America (1984). Chauncy D. Harris et al. (eds.), A Geographical Bibliography for American Libraries (1985), focuses on the period 197084, though earlier works are also included; while Gordon R. Lewthwaite, Edward T. Price, Jr., and Harold A. Winters (comps. and eds.), A Geographical Bibliography for American College Libraries, rev. ed. (1970), is particularly useful for the period before 1970. Geographical Abstracts (monthly), is the fullest bibliography in English and is especially strong in systematic fields of geography. Current Geographical Publications (monthly) concentrates on American publications. Bibliographie Gographie Internationale (quarterly) is international in scope and the best bibliography on regional geography. Periodicals Leading international journals in English include Annals of the Association of American Geographers (quarterly); Canadian Geographer/Geographe Canadien (quarterly); Geographical Journal (3/yr.); Geographical Review (quarterly); and Transactions of the Institute of British Geographers (quarterly). See also Chauncy D. Harris, Annotated World List of Selected Current Geographical Serials, 4th ed. (1980), which annotates 443 of the most valuable current serials from 72 countries. Dictionaries Audrey N. Clark, Longman Dictionary of Geography: Human and Physical (1985), offers good brief definitions of terms in all fields. R.J. Johnston (ed.), The Dictionary of Human Geography, 2nd ed. (1986), includes advanced, signed definitions. Andrew Goudie et al., The Encyclopaedic Dictionary of Physical Geography (1985), is authoritative, with a focus on concepts. Chauncy D. Harris Fields of modern geography Geography is divided into systematic fields and regional specializations, which can be grouped under three main headings: physical geography, human geography, and regional geography. Physical geography The principal activities of the physical geographerobserving, measuring, and describing the surface of the Earthare those aspects of the larger discipline of geography that are the most recognizable to the layperson. Even so, the growing complexity of geographic inquiry has resulted in increased specialization within the field. The principal branches of physical geography are geomorphology, climatology, biogeography, and soil geography. As human activity has become more able to affect the landscape and ecology of the world, two more branches have emerged: resource management and environmental studies. Geographic methods Map location and measurement The map is the distinctive data bank of the geographer. Since geography deals particularly with locations, distributions, areal associations, and interrelationships of phenomena in space, accurate observation and measurement of the surface of the Earth and the recording and displaying of location on maps are of prime importance. Latitude and longitude are commonly utilized for plotting locations on the surface of the globe. Fairly accurate measurements of latitude were made in antiquity by Greek scholars. Measurements of longitude remained rough, however, because of the difficulty in measuring differences in solar time (the Sun moves westward at the mean rate of one degree each four minutes). The perfection of the chronometer solved this problem, but for long each country had its own system for numbering the meridians. Finally, by an international agreement reached in 1884, an imaginary line from pole to pole through Greenwich, near London, was recognized as the prime meridian (i.e., 0 longitude). Measurement of direction, or bearing, was aided considerably by use of the magnetic compass, but as Christopher Columbus noted in crossing the Atlantic, the direction in which the compass pointed varied with longitude. The measurement of distances overland could be counted in days of journey on foot, by camel, by horse, or by other means. More accurate measurements of short distances were obtained by using a chain, and the chain as a unit of length (66 feet) is still a traditional surveying measure in English-speaking countries. Later, the chain itself was replaced by a steel tape, and still later electronic instruments came into use. A practical measurement of distances at sea was developed in the 16th century: a log was thrown overboard and the amount of time it took the stationary log to play out a certain distance on a line marked off with knots was measured. Navigation by means of satellites is now available, but a ship's speed is still measured in knots and records are kept in a logbook. After the adoption of the metre as a standard unit in France in the late 18th century, it gradually replaced older local and national measures of distance over much of the world during the 19th and 20th centuries. Maps of small areastopographic maps, for examplecan be made by a method called triangulation. A base-line is measured with chains or other devices, and by using this base as one side of a triangle the other sides are calculated from the angles at the two ends of the base-line. Angles can be measured more easily and accurately than distances, and from the points on the corners of the original triangle, a network of points joined by triangles can be established. Triangulation was known to the ancient Egyptians and Greeks; with improved instruments, especially the theodolite, this method was utilized in the great national surveys of Europe and America from the 18th to the 20th century. How to represent the entire, spherical Earth or large areas of it on maps remained a problem. In 1492 the German navigator and geographer Martin Behaim completed the construction of a terrestrial globe. Ships following straight lines on flat maps, however, did not arrive at expected points. Mercator devised a map projectionwhich became known as the Mercator projectionon which ships following straight lines would arrive at the plotted points. Although the projection was excellent for navigation, it was poor for many geographic comparisons, since the size of areas in the higher latitudes becomes grossly exaggerated; Greenland, for example, appears to be larger than South America, though in fact it is less than one-eighth as large. The Earth cannot be shown accurately in all respects on a flat piece of paper since either bearing (angle), distance, or scale must be distorted. Modern geographers use maps drawn in what is called the equal-area projection, but even this projection distorts shapes or distances, particularly toward the edges of the map. With the increasing specialization of knowledge, measuring the shape of the Earth developed into the discipline of geodesy, plotting land positions for detailed maps became the province of surveying, and constructing numerous types of maps with appropriate projections grew into the field of cartography. Maps have remained as the basic tools in geography for plotting and analyzing a vast range of physical, biologic, historical, economic, political, and social data. Geography and cartography are closely associated: many geographers are cartographers and a significant number of cartographers are geographers, and cartographic training is widely available in departments of geography in universities and colleges. Aerial photography and remote sensing During the 20th century immense strides have been made in observing features on the Earth's surface, first by the development of aerial photography and later by satellite imagery. Aerial photography was first used extensively during World War I for reconnaissance. A new profession of photographic interpretation evolved in which the identification of both natural and man-made features became a special skill. After the war aerial photographs quickly proved their usefulness in mapping landforms, land uses, types of forest, vegetation, and the limits of the built-up areas of cities; in locating archaeological sites; and, in the United States, in measuring the size of farm fields and crop acreages in agricultural programs of the federal government and as the basis for county soil surveys. The perfection of stereoscopic plotting from overlapping aerial photographs greatly improved contour mapping in the production of topographic maps. The development of side-looking airborne radar made possible rapid surveys of large tracts of land, particularly in areas of economically underdeveloped countries that were not easily accessible by other means. Colour photographic film and infrared imagery also increased the potential for measurement of many aspects of land use or of physical processes. Even more revolutionary was the rapid evolution from the late 1950s of remote sensing using artificial satellites. Simultaneous, or synoptic, worldwide patterns could be viewed for the first time. The first weather satellite, called Nimbus, was launched in 1964. The advances in meteorology provide a particularly vivid example. Although humans had been observing the weather for countless ages and all major countries had dense networks of weather stations, satellites finally made it possible to clearly recognize many cloud patterns, such as the huge spiral cloud formations of major weather systems. By using weather satellites in combination with communication satellites, cloud and rainfall patterns could be presented almost instantaneously to worldwide television audiences. The rapid advances in space technology and multiband remote sensing allowed for a wide range of physical and man-made features to be observed, mapped, and studied with a comprehensiveness not previously possible. Data from geodetic satellites gave a much more exact determination of the shape of the Earth and revealed many irregularities not previously recognized. With the advent of navigation satellites locations could be determined with much greater precision. When astronauts traveled to the Moon people saw for the first time the whole terrestrial globe as a unity (though, of course, only half could be seen at one time).
Meaning of GEOGRAPHY in English
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