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  • Climate and the Weather | Britannica.com
    as high as Aitken John Scottish physicist and meteorologist who through a series of experiments and observations in which he used apparatus of his own design elucidated the crucial role that microscopic particles now called Aitken nuclei play in the condensation of atmospheric Aleutian low large atmospheric low pressure cyclonic centre that frequently exists over the Aleutian Islands region in winter and that shifts northward and almost disappears in summer Although the Aleutian low is associated with smaller eastward moving low and anabatic wind local air current that blows up a hill or mountain slope facing the Sun During the day the Sun heats such a slope and the air over it faster than it does the adjacent atmosphere over a valley or a plain at the same altitude This warming decreases Andrew Hurricane tropical cyclone that ravaged The Bahamas southern Florida and south central Louisiana in late August 1992 At the time Hurricane Andrew was the most expensive Atlantic hurricane in U S history later surpassed by Hurricane Katrina in 2005 Hurricane 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 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 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 Australia floods of 2010 2011 natural disaster that principally affected the three eastern states of Australia and was one of the worst in the country s history Queensland in the north was hit hardest but the widespread flooding of a scale not seen since the mid 1970s that began autumn season of the year between summer and winter during which temperatures gradually decrease It is often called fall in the United States because leaves fall from the trees at that time Autumn is usually defined in the Northern Hemisphere as the period Azores high large persistent atmospheric high pressure centre that develops over the subtropical region of the eastern North Atlantic Ocean during the winter and spring seasons in the Northern Hemisphere It is a subtropical high pressure cell that moves westward ball lightning a rare aerial phenomenon in the form of a luminous sphere that is generally several centimetres in diameter It usually occurs near the ground during thunderstorms in close association with cloud to ground lightning It may be red orange yellow white Bangladesh cyclone of 1991 April 22 30 1991 one of the deadliest tropical cyclones ever recorded The storm hit near the Chittagong region one of the

    Original URL path: http://www.britannica.com/topic-browse/Earth-and-Geography/Climate-and-the-Weather (2016-02-13)
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  • Continents | Britannica.com
    and of Melaka 1511 on the Malay Peninsula His program to gain control of all the main maritime trade routes of the East and to build permanent fortresses with settled populations laid the foundations Anderson Maxie balloonist who with Ben Abruzzo and Larry Newman made the first transatlantic balloon flight and with his son Kristian made the first nonstop trans North American balloon flight Anderson entered the Missouri Military Academy Mexico Mo at the Andreis Felix de Vincentian priest and pioneer missionary to the American West Ordained at Piacenza Italy in 1802 Andreis was transferred 1806 to Rome where he served as preacher professor of theology and apostle to the poor While on a visit to Rome in 1815 Andrews Roy Chapman naturalist explorer and author who led many important scientific expeditions for which he obtained financial support through his public lectures and books particularly on central Asia and eastern Asia After graduating from Beloit Wis College Antarctica fifth in size among the world s continents Its landmass is almost wholly covered by a vast ice sheet Lying almost concentrically around the South Pole Antarctica the name of which means opposite to the Arctic is the southernmost continent a circumstance Arrowsmith Aaron British geographer and cartographer who engraved and published many fine maps and atlases based on the best available sources of the day Without a formal education Arrowsmith went to London c 1770 and after working as a surveyor established himself Asia the world s largest and most diverse continent It occupies the eastern four fifths of the giant Eurasian landmass Asia is more a geographic term than a homogeneous continent and the use of the term to describe such a vast area always carries the potential Australia the smallest continent and one of the largest countries on Earth lying between the Pacific and Indian oceans in the Southern Hemisphere Australia s capital is Canberra located in the southeast between the larger and more important economic and cultural Bancroft Ann American explorer who was the first woman to participate in and successfully finish several arduous expeditions to the Arctic and Antarctic Bancroft grew up in rural Minnesota in what she described as a family of risk takers Although she struggled Barton Sir Edmund statesman who guided the Australian federation movement to a successful conclusion and became the first prime minister of the resulting commonwealth in 1901 Barton in 1879 entered the New South Wales Legislative Assembly where he served as speaker Bartram John naturalist and explorer considered the father of American botany Largely self educated Bartram was a friend of Benjamin Franklin and an original member of the American Philosophical Society He was botanist for the American colonies to King George Bass George surgeon and sailor who was important in the early coastal survey of Australia Bass was apprenticed as a surgeon and in 1789 accepted in the Company of Surgeons He joined the Royal Navy where his proficiency in navigation and seamanship and interest Bellingshausen Fabian Gottlieb von

    Original URL path: http://www.britannica.com/topic-browse/Earth-and-Geography/Continents (2016-02-13)
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  • Earth | Britannica.com
    a mixture of clay sand and silt with good plastic qualities that will dry to a hard uniform mass In areas with arid advection in atmospheric science change in a property of a moving mass of air because the mass is transported by the wind to a region where the property has a different value e g the change in temperature when a warm air mass moves into a cool region Advection aerosol a system of liquid or solid particles uniformly distributed in a finely divided state through a gas usually air Aerosol particles such as dust play an important role in the precipitation process providing the nuclei upon which condensation and freezing Africa the second largest continent after Asia covering about one fifth of the total land surface of the Earth The continent is bounded on the west by the Atlantic Ocean on the north by the Mediterranean Sea on the east by the Red Sea and the Indian Ocean aftershock any of several lower magnitude earthquakes that follow the main shock of a larger earthquake An aftershock results from the sudden change in stress occurring within and between rocks and the previous release of stress brought on by the principal earthquake Agricola Georgius German scholar and scientist known as the father of mineralogy While a highly educated classicist and humanist well regarded by scholars of his own and later times he was yet singularly independent of the theories of ancient authorities He was air 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 air mass 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 air sea interface boundary between the atmosphere and the ocean waters The interface is one of the most physically and chemically active of the Earth s environments Its neighbourhood supports most marine life The atmosphere gains much of its heat at the interface in airglow faint luminescence of Earth s upper atmosphere that is caused by air molecules and atoms selective absorption of solar ultraviolet and X radiation Most of the airglow emanates from the region about 50 to 300 km 31 to 180 miles above the surface alabaster fine grained massive gypsum that has been used for centuries for statuary carvings and other ornaments It normally is snow white and translucent but can be artificially dyed it may be made opaque and similar in appearance to marble by heat treatment Alaska earthquake of 1964 earthquake that occurred in south central Alaska on March 27 1964 with a moment magnitude of 9 2 It released at least twice as much energy as the San Francisco earthquake of 1906 and was felt on

    Original URL path: http://www.britannica.com/topic-browse/Earth-and-Geography/Earth (2016-02-13)
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  • Earth Sciences | Britannica.com
    atmosphere including the distribution of temperature density and chemical constituents and the chemical reactions that occur Studies of aurora airglow the ionosphere Van Allen radiation belts cosmic aerosol a system of liquid or solid particles uniformly distributed in a finely divided state through a gas usually air Aerosol particles such as dust play an important role in the precipitation process providing the nuclei upon which condensation and freezing aftershock any of several lower magnitude earthquakes that follow the main shock of a larger earthquake An aftershock results from the sudden change in stress occurring within and between rocks and the previous release of stress brought on by the principal earthquake Agricola Georgius German scholar and scientist known as the father of mineralogy While a highly educated classicist and humanist well regarded by scholars of his own and later times he was yet singularly independent of the theories of ancient authorities He was air 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 air mass 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 air sea interface boundary between the atmosphere and the ocean waters The interface is one of the most physically and chemically active of the Earth s environments Its neighbourhood supports most marine life The atmosphere gains much of its heat at the interface in airglow faint luminescence of Earth s upper atmosphere that is caused by air molecules and atoms selective absorption of solar ultraviolet and X radiation Most of the airglow emanates from the region about 50 to 300 km 31 to 180 miles above the surface Aitken John Scottish physicist and meteorologist who through a series of experiments and observations in which he used apparatus of his own design elucidated the crucial role that microscopic particles now called Aitken nuclei play in the condensation of atmospheric Aleutian low large atmospheric low pressure cyclonic centre that frequently exists over the Aleutian Islands region in winter and that shifts northward and almost disappears in summer Although the Aleutian low is associated with smaller eastward moving low and Alleghenian orogeny mountain building event occurring almost entirely within the Permian Period 299 million to 251 million years ago that created the Appalachian Mountains The Alleghenian orogeny resulted from the collision of the central and southern Appalachian continental alluvium material deposited by rivers It is usually most extensively developed in the lower part of the course of a river forming floodplains and deltas but may be deposited at any point where the river overflows its banks or where the velocity of a river Alpine orogeny mountain building event that affected a broad segment of southern Europe and the

    Original URL path: http://www.britannica.com/topic-browse/Earth-and-Geography/Earth-Sciences (2016-02-13)
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  • Oceans and Seas | Britannica.com
    1912 and joined the Royal Naval Air Service as an instructor at the opening of World War I In 1916 he was Amphitrite in Greek mythology the goddess of the sea wife of the god Poseidon and one of the 50 or 100 daughters the Nereids of Nereus and Doris the daughter of Oceanus Poseidon chose Amphitrite from among her sisters as the Nereids performed a dance Amundsen Roald Norwegian explorer who was the first to reach the South Pole the first to make a ship voyage through the Northwest Passage and one of the first to cross the Arctic by air He was one of the greatest figures in the field of polar exploration Amundsen Andaman Sea marginal sea of the northeastern Indian Ocean It is bounded to the north by the Irrawaddy River delta of Myanmar Burma to the east by peninsular Myanmar Thailand and Malaysia to the south by the Indonesian island of Sumatra and by the Strait of Anderson Maxie balloonist who with Ben Abruzzo and Larry Newman made the first transatlantic balloon flight and with his son Kristian made the first nonstop trans North American balloon flight Anderson entered the Missouri Military Academy Mexico Mo at the Aquarius SAC D joint U S Argentine space mission to map the salinity of Earth s oceans Aquarius Satélite de Aplicaciones Científicas D SAC D was launched by a Delta II rocket from Vandenberg Air Force Base in California on June 10 2011 Salinity or salt content Arabian Sea northwestern part of the Indian Ocean covering a total area of about 1 491 000 square miles 3 862 000 square km and forming part of the principal sea route between Europe and India It is bounded to the west by the Horn of Africa and the Arabian Peninsula Arafura Sea shallow sea of the western Pacific Ocean occupying 250 000 square miles 650 000 square km between the north coast of Australia Gulf of Carpentaria and the south coast of New Guinea It merges with the Timor Sea on the west and the Banda and Ceram Aral Sea a once large saltwater lake of Central Asia It straddles the boundary between Kazakhstan to the north and Uzbekistan to the south The shallow Aral Sea was once the world s fourth largest body of inland water The remnants of it nestle in the climatically Arctic Ocean smallest of the world s oceans centring approximately on the North Pole The Arctic Ocean and its marginal seas the Chukchi East Siberian Laptev Kara Barents White Greenland and Beaufort and according to some oceanographers also the Bering Arrowsmith Aaron British geographer and cartographer who engraved and published many fine maps and atlases based on the best available sources of the day Without a formal education Arrowsmith went to London c 1770 and after working as a surveyor established himself Atlantic Ocean body of salt water covering approximately one fifth of Earth s surface and separating the continents of Europe and Africa to

    Original URL path: http://www.britannica.com/topic-browse/Earth-and-Geography/Oceans-and-Seas (2016-02-13)
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  • Physical Geography | Britannica.com
    km northeastward to Adam Bay an inlet of the Timor Sea on Clarence Strait From its Adige River longest stream of Italy after the Po River The Adige rises in the north from two Alpine mountain lakes below Resia Pass and flows rapidly through the Venosta Valley south and east past Merano and Bolzano Having received the waters of the Isarco River Adour River river in southwestern France The Adour River rises in the central Pyrenees near Tourmalet Pass just south of Midi de Bigorre Peak and flows in a curve north then west to enter the Bay of Biscay just below Bayonne after a course of 208 miles 335 Afram River river in southern Ghana western Africa It rises 16 miles 26 km northwest of Mampong and flows southeast into Lake Volta formerly the Afram was a tributary of the Volta River The Afram is about 55 miles 90 km long The river is important for Africa the second largest continent after Asia covering about one fifth of the total land surface of the Earth The continent is bounded on the west by the Atlantic Ocean on the north by the Mediterranean Sea on the east by the Red Sea and the Indian Ocean Aguán River river in northern Honduras 150 mi 240 km in length After rising in the central highlands west of Yoro it descends to the northeast between the Cerros de Cangreja and the Sierra de la Esperanza to the coastal lowlands on which it forms a maze of Agusan River longest river in Mindanao Philippines It rises in the southeast and flows northward for 240 miles 390 km to enter Butuan Bay of the Bohol Sea The river forms a fertile valley 40 to 50 miles 65 80 km wide between the Central Mindanao Highlands Aire River river rising at Malham Tarn lake in North Yorkshire administrative county historic county of Yorkshire England It drains the central Pennines and flows southeastward through West Yorkshire metropolitan county and across the southern part of North Alabama River river in southern Alabama U S It is formed by the Coosa and Tallapoosa rivers 7 miles 11 km northeast of Montgomery winds westward to Selma and then flows southward Its navigable length is 305 miles 491 km and the river drains 22 800 square Albany River river north central Ontario Canada rising in Lake St Joseph at an elevation of 1 218 ft 371 m and flowing generally eastward into James Bay For 250 mi 400 km of its 610 mi course the river is navigable and it served as an important route during Aliákmon River river the longest in Greek Macedonia Modern Greek Makedonía The river s total length is 185 miles 297 km Rising in the Grámmos Mountains of the eastern Pindus Píndos Range on the Albanian frontier the Aliákmon River flows southeast through Allegheny River river rising in the hilly plateau region of Potter county Pennsylvania U S and flowing generally northward for about 80 miles

    Original URL path: http://www.britannica.com/topic-browse/Earth-and-Geography/Physical-Geography (2016-02-13)
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  • Political Geography | Britannica.com
    Alabama constituent state of the United States of America admitted in 1819 as the 22nd state Alabama forms a roughly rectangular shape on the map elongated in a north south direction It is bordered by Tennessee to the north Georgia to the east and Mississippi Alagoas estado state of northeastern Brazil It is the second smallest of Brazil s states and is an agricultural region in the early stages of industrialization Situated on the northern bank of the São Francisco River it is bounded on the north and west Alaska constituent state of the United States of America It was admitted to the union as the 49th state on January 3 1959 Alaska lies at the extreme northwest of the North American continent and is the largest peninsula in the Western Hemisphere Because Albania country in southern Europe located in the western part of the Balkan Peninsula on the Strait of Otranto the southern entrance to the Adriatic Sea The capital city is Tirana Tiranë Albanians refer to themselves as shqiptarë often taken to mean Albany county east central New York state U S bordered by the Mohawk River to the northeast and the Hudson River to the east The terrain rises from the Hudson valley lowlands in the east to the Helderberg Mountains in the centre of the county Alcove Reservoir Alberta most westerly of Canada s three Prairie Provinces occupying the continental interior of the western part of the country To the north the 60th parallel latitude 60 N forms its boundary with the Northwest Territories to the east the 110th meridian Albuquerque city seat 1883 of Bernalillo county west central New Mexico U S located on the Rio Grande opposite a pass between the Sandia and Manzano mountains to the east The area was the site of Native American pueblos villages when Europeans first arrived Aleppo principal city of northern Syria It is situated in the northwestern part of the country about 30 miles 50 km south of the Turkish border Aleppo is located at the crossroads of great commercial routes and lies some 60 miles 100 km from both the Alexandria major city and urban muḥāfaẓah governorate in Egypt Once among the greatest cities of the Mediterranean world and a centre of Hellenic scholarship and science Alexandria was the capital of Egypt from its founding by Alexander the Great in 332 bce Algeria large predominantly Muslim country of North Africa From the Mediterranean coast along which most of its people live Algeria extends southward deep into the heart of the Sahara a forbidding desert where the Earth s hottest surface temperatures have Algiers capital and chief seaport of Algeria It is the political economic and cultural centre of the country Algiers is built on the slopes of the Sahel Hills which parallel the Mediterranean Sea coast and it extends for some 10 miles 16 km along the Allegheny county southwestern Pennsylvania U S consisting of a hilly region on the Allegheny Plateau bounded to the southeast

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  • Earth and Geography - 3 | Britannica.com
    1838 Daubrée became regional mining engineer for the département of Haut Rhin where he worked for eight years on a geologic map Davis William Morris U S geographer geologist and meteorologist who founded the science of geomorphology the study of landforms In 1870 he began three years of service as a meteorologist with the Argentine Meteorological Observatory Córdoba In 1876 he obtained a position Day Arthur L U S geophysicist known for his studies of the properties of rocks and minerals at very high and very low temperatures He investigated hot springs and earthquakes the absolute measurement of high temperatures and physical and chemical problems regarding De Grey River river in northwestern Western Australia It rises as the Oakover River in the Robertson Range 150 miles 240 km southeast of Marble Bar and flows north Midway in its course it turns northwest to join the Nullagine River and becomes the De Grey Delaware River river of the Atlantic slope of the United States meeting tidewater at Trenton N J about 130 miles 210 km above its mouth Its total length including the longest branch is about 405 miles 650 km and the river drains an area of 11 440 square Deluc Jean André Swiss born British geologist and meteorologist whose theoretical work was influential on 19th century writing about meteorology Deluc was educated in mathematics and the natural sciences He engaged in business and on his business travels around Europe Derwent River river in Tasmania Australia rising in Lake St Clair on the central plateau and flowing 113 miles 182 km southeast to enter Storm Bay through a 3 5 mile 5 5 kilometre wide estuary Its major upper course tributaries the Jordan Clyde Ouse now Derwent River river in North Yorkshire England that rises on Fylingdales Moor only 6 miles 10 km inland from the North Sea but flows 57 miles 92 km through alternating gorges and vales to its junction with the River Ouse This peculiar course results from the Des Moines River river rising in Lake Shetek in southwestern Minnesota U S near Pipestone and flowing 525 mi 845 km in a southeasterly direction to join the Mississippi River 2 mi southwest of Keokuk Iowa Above Humboldt Iowa the river is known as the West Fork Des Plaines River river rising in Kenosha county southeastern Wisconsin U S and flowing south into Illinois through the northwestern suburbs of Chicago to Lyons It then continues southwest past Lockport and Joliet where it joins the Kankakee River after a course desert any large extremely dry area of land with sparse vegetation It is one of Earth s major types of ecosystems supporting a community of distinctive plants and animals specially adapted to the harsh environment For a list of selected deserts of the world desertification the process by which natural or human causes reduce the biological productivity of drylands arid and semiarid lands Declines in productivity may be the result of climate change deforestation overgrazing poverty political instability unsustainable Detroit River river forming part of the boundary between Michigan U S west and Ontario Can east and connecting Lake St Clair north with the west end of Lake Erie south The river flows southwest and south for 32 miles 51 km between Detroit and Windsor dew deposit of waterdrops formed at night by the condensation of water vapour from the air onto the surfaces of objects freely exposed to the sky see It forms on clear nights when the air is calm or preferably when the wind is light If the temperature Dines William Henry British meteorologist who invented instruments to measure atmospheric properties The son of a meteorologist Dines was graduated from Corpus Christi College Cambridge with honours He became interested in wind speed and invented a pressure tube anemometer Diyālā River river important tributary of the Tigris River rising in the Zagros Mountains of western Iran near Hamadān as the Sīrvān River and flowing westward across lowlands to join the Tigris just below Baghdad Iraq Its total length is 275 miles 443 km Dnieper River river of Europe the fourth longest after the Volga Danube and Ural It is 1 367 miles 2 200 km in length and drains an area of about 195 000 square miles 505 000 square km The Dnieper rises at an elevation of about 720 feet 220 metres in a Dniester River river of southwestern Ukraine and of Moldova rising on the north side of the Carpathian Mountains and flowing south and east for 840 miles 1 352 km to the Black Sea near Odessa It is the second longest river in Ukraine and the main water artery of Dolores River river in southwest Colorado U S rising in the La Plata Mountains and flowing southwest through deep canyons past Dolores then northwest through Paradox Valley at the north end of which it is met by its chief tributary the San Miguel River It Don River one of the great rivers of the European portion of Russia It has been a vital artery in Russian history since the days of Peter I the Great who initiated a hydrographic survey of its course Throughout the world the river is associated with images Donets River a tributary of the Don River southwestern Russia and eastern Ukraine The Donets is 650 miles 1 050 km long and drains a basin of 39 000 square miles 100 000 square km Rising in the Central Russian Upland it flows south past Belgorod Russia Dong Nai River river rising in the central highlands Annamese Cordillera of southern Vietnam northwest of Da Lat Near its source the river has rapids and is known as the Da Dung River It flows west and southwest for about 300 miles 480 km joining the Saigon Dordogne River river in southwestern France rising in the Massif Central and flowing west for 293 mi 472 km to Bec d Ambès north of Bordeaux where it unites with the Garonne to form the Gironde Estuary

    Original URL path: http://www.britannica.com/topic-browse/Earth-and-Geography/3 (2016-02-13)
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