262 résultats pour "averages"

• Pollution.

  One of the greatest challenges caused by air pollution is global warming, an increase in Earth’s temperature due to the buildup of certain atmospheric gases such ascarbon dioxide. With the heavy use of fossil fuels in the 20th century, atmospheric concentrations of carbon dioxide have risen dramatically. Carbon dioxide and othergases, known as greenhouse gases, reduce the escape of heat from the planet without blocking radiation coming from the Sun. Because of this greenhouse effect,average glob...

• Great Depression in the United States - U.

  prices would continue to rise and they could soon sell their stocks at a profit. The widespread belief that anyone could get rich led many less affluent Americans into the market as well. Investors bought millions of shares of stock “on margin,” arisky practice similar to buying products on credit. They paid only a small part of the price and borrowed the rest, gambling that they could sell the stock at a highenough price to repay the loan and make a profit. For a time this was true: In 1928 the...

• Globalization.

  higher living standard for their people. The World Bank made loans to developing countries for dams and other electrical-generating plants, harbor facilities, and otherlarge projects. These projects were intended to lower costs for private businesses and to attract investors. Beginning in 1968 the World Bank focused on low-cost loansfor health, education, and other basic needs of the world’s poor. B International Monetary Fund The IMF makes loans so that countries can maintain the value of thei...

• Federal Republic of Germany - country.

  B Rivers and Lakes Rivers have played a major role in Germany’s economic development. The Rhine River flows in a northwesterly direction from Switzerland through much of westernGermany and The Netherlands into the North Sea. It is a major European waterway and a pillar of commerce and trade. Its primary German tributaries include theMain, Mosel, Neckar, and Ruhr rivers. The Oder (Odra) River, along the border between Poland and Germany, runs northward and empties into the Baltic; it provides an...

• Guinea - country.

  Mining operations in 2004 yielded 16 million metric tons of bauxite, 468,400 carats of high-quality diamonds, and 16,000 kg (35,300 lb) of gold. Environmental concernsand political instability in neighboring Liberia have delayed exploitation of high-grade iron ore from Mount Nimba. In 1999 the national budget included $466 million in revenues and $414 million in expenditures. The unit of currency is the Guinean franc, which is divided into 100 centimes (3,644 francs equal U.S.$1; 2005 average...

• China - country.

  North China lies between the Mongolian Steppe on the north and the Yangtze River Basin on the south. It stretches west from the Bo Hai gulf and the Yellow Sea to theeastern edge of the Tibetan Plateau. Administratively, North China includes Beijing and Tianjin municipalities; Shandong and Shanxi provinces; most of Hebei, Henan,and Shaanxi provinces; and portions of Ningxia Hui Autonomous Region and of Jiangsu, Anhui, and Gansu provinces. Humans have lived in the agriculturally rich region of Nor...

• Kenya - country.

  threatens fish and other water life in the lake by depriving them of oxygen. Kenya is well known for its game parks—including Masai Mara Game Park and Tsavo National Park in the south, and Marsabit National Reserve in the north—whichattract large numbers of tourists and much revenue. Conservation of wildlife within reserves has thus received high priority. About 13 percent (2007) of Kenya’s totalland is protected. There are 229 (2004) threatened species in Kenya. Threatened habitats include the...

• Canada.

  Six general landform regions are distinguishable in Canada: the Appalachian Region, the Great Lakes and St. Lawrence Lowlands, the Canadian Shield, the Great Plains,the Canadian Cordillera, and the Canadian Arctic Archipelago. B1 Appalachian Region and Great Lakes and St. Lawrence Lowlands Eastern Canada consists of the Appalachian Region and the Great Lakes and St. Lawrence Lowlands. The Appalachian Region embraces Newfoundland Island, NovaScotia, New Brunswick, Prince Edward Island, and the G...

• Canada - country.

  Six general landform regions are distinguishable in Canada: the Appalachian Region, the Great Lakes and St. Lawrence Lowlands, the Canadian Shield, the Great Plains,the Canadian Cordillera, and the Canadian Arctic Archipelago. B1 Appalachian Region and Great Lakes and St. Lawrence Lowlands Eastern Canada consists of the Appalachian Region and the Great Lakes and St. Lawrence Lowlands. The Appalachian Region embraces Newfoundland Island, NovaScotia, New Brunswick, Prince Edward Island, and the G...

• Canada - Canadian History.

  Six general landform regions are distinguishable in Canada: the Appalachian Region, the Great Lakes and St. Lawrence Lowlands, the Canadian Shield, the Great Plains,the Canadian Cordillera, and the Canadian Arctic Archipelago. B1 Appalachian Region and Great Lakes and St. Lawrence Lowlands Eastern Canada consists of the Appalachian Region and the Great Lakes and St. Lawrence Lowlands. The Appalachian Region embraces Newfoundland Island, NovaScotia, New Brunswick, Prince Edward Island, and the G...

• Congress of the United States.

  senator, a person must be at least 30 years old, a citizen for nine years, and a resident of the state from which he or she is elected. Most members of Congress haveserved in state legislatures, city councils, or other elected bodies. See United States Senate: Campaigning for the Senate ; United States House of Representatives: Campaigning for the House. The 435 House seats are divided among the states in proportion to each state’s population. Every state is guaranteed at least one seat. State...

• Arkansas - geography.

  temperature rises to the upper 30°s C (lower 100°s F). C2 Precipitation Arkansas receives about 1,000 to 1,300 mm (about 40 to 50 in) of precipitation a year, and some areas receive even more. Most of the rain comes during winter andspring and at times is so heavy as to cause flooding. Snow is rare in the south but amounts to more than 250 mm (10 in) a year in the mountains. C3 Growing Season Arkansas has a long growing season. It averages 211 days for the state as a whole and ranges from 241...

• Arkansas - USA History.

  temperature rises to the upper 30°s C (lower 100°s F). C2 Precipitation Arkansas receives about 1,000 to 1,300 mm (about 40 to 50 in) of precipitation a year, and some areas receive even more. Most of the rain comes during winter andspring and at times is so heavy as to cause flooding. Snow is rare in the south but amounts to more than 250 mm (10 in) a year in the mountains. C3 Growing Season Arkansas has a long growing season. It averages 211 days for the state as a whole and ranges from 241...

• Wisconsin (state) - geography.

  -6° C (22° F) in the southeast, along the Lake Michigan shore. During winter extremely cold weather persists for several weeks at a time. C2 Precipitation Average annual precipitation ranges from 700 to 800 mm (28 to 32 in). Rainfall is generally heaviest during the spring and summer, and snowfall is generally moderatein the south, but can be quite heavy in the north. Thunderstorms, sometimes accompanied by devastating tornadoes, are common in spring and summer, particularly inthe southern part...

• Wisconsin (state) - USA History.

  -6° C (22° F) in the southeast, along the Lake Michigan shore. During winter extremely cold weather persists for several weeks at a time. C2 Precipitation Average annual precipitation ranges from 700 to 800 mm (28 to 32 in). Rainfall is generally heaviest during the spring and summer, and snowfall is generally moderatein the south, but can be quite heavy in the north. Thunderstorms, sometimes accompanied by devastating tornadoes, are common in spring and summer, particularly inthe southern part...

• Mexico City - geography.

  The park houses some of Mexico's most important public buildings, including Chapultepec Castle. Construction of the castle began in 1783. Positioned on the park’shighest elevation, the castle functioned as a fortress during colonial times. It once served as the presidential residence and now houses the National Museum of History,which includes murals by 20th-century Mexican painter Juan O'Gorman. Los Pinos, the official residence and working offices of the president, is also on the grounds, buti...

• Albania - country.

  Joining the international community in its concern over the degradation of the environment, Albania is party to international agreements concerning biodiversity, climatechange, and wetlands. III THE PEOPLE OF ALBANIA In 2008 Albania’s population estimate was 3,619,778, resulting in an average density of 132 persons per sq km (342 per sq mi). More and more people have left ruralareas for urban ones, particularly in the northern districts, such that in 2005 some 45 percent of the population live...

• Sun - astronomy.

  A The Sun’s Place in the Milky Way The Milky Way Galaxy contains about 400 billion stars. All of these stars, and the gas and dust between them, are rotating about a galactic center. Stars that arefarther away from the center move at slower speeds and take longer to go around it. The Sun is located in the outer part of the galaxy, at a distance of 2.6 × 10 17 km (1.6 × 10 17 mi) from the center. The Sun, which is moving around the center at a velocity of 220 km/s (140 mi/s), takes 250 million y...

• Alaska - geography.

  depression surrounded by highlands and have the coldest winter and hottest summer temperatures in Alaska. Once the Kuskokwim River passes through theKuskokwim Mountains, it forms the southern edge of a vast lake-studded alluvial plain bounded on the north by the Yukon River. This water-logged lowland is a majorsummer nesting area for birds. Fairbanks is the major city in this region, while Fort Yukon is the major community in the Yukon Flats and Bethel the largest settlementon the Lower Kuskokwi...

• Alaska - USA History.

  depression surrounded by highlands and have the coldest winter and hottest summer temperatures in Alaska. Once the Kuskokwim River passes through theKuskokwim Mountains, it forms the southern edge of a vast lake-studded alluvial plain bounded on the north by the Yukon River. This water-logged lowland is a majorsummer nesting area for birds. Fairbanks is the major city in this region, while Fort Yukon is the major community in the Yukon Flats and Bethel the largest settlementon the Lower Kuskokwi...

• Spain - country.

  B Natural Resources Spain has a number of mineral resources. The largest known deposits are of iron ore, zinc, and lead. Spain also produces significant quantities of copper and mercury.These deposits are mined mainly in Huelva province in southwestern Spain, around Cartagena on the Mediterranean, and at various points along the Bay of Biscay inthe north. Additionally, uranium is mined in the region of Extremadura, near the Portuguese frontier, where pyrites, fluorspar, gypsum, tungsten, and po...

• National Basketball Association Records.

  Elmore Smith 1973-74 4.85 Mark Eaton 1985-86 4.61 Hakeem Olajuwon 1989-90 4.59 Dikembe Mutombo 1995-96 4.49 David Robinson 1991-92 4.49 Hakeem Olajuwon 1991-92 4.34 Manute Bol 1988-89 4.31 Tree Rollins 1982-83 4.29 1. Introduced in the 1979-80 season.2. Did not become an official statistic until 1973-74 season. Source: National Basketball Association.. NBA Records - Career.Player Total Points Kareem Abdul-Jabbar 38,387 Karl Malone 36,928 Michael Jordan 32,292 Wilt Chamberlain 31,419 Moses Mal...

• National Basketball Association Records.

  Elmore Smith 1973-74 4.85 Mark Eaton 1985-86 4.61 Hakeem Olajuwon 1989-90 4.59 Dikembe Mutombo 1995-96 4.49 David Robinson 1991-92 4.49 Hakeem Olajuwon 1991-92 4.34 Manute Bol 1988-89 4.31 Tree Rollins 1982-83 4.29 1. Introduced in the 1979-80 season.2. Did not become an official statistic until 1973-74 season. Source: National Basketball Association.. NBA Records - CareerPlayer Total Points Kareem Abdul-Jabbar 38,387 Karl Malone 36,928 Michael Jordan 32,292 Wilt Chamberlain 31,419 Moses Malo...

• Elephant - biology.

  B Trunk An elephant's nose and upper lip are combined in a long, limber trunk, an exceptionally supple appendage with an estimated 150,000 muscles. The versatile trunk actslike a hand for grasping low-growing shrubs and other food and placing it into the mouth; an arm for breaking off tree branches; or a snorkel for breathing when theelephant's body is submerged. Elephants also use their trunks to suck up water and squirt it into their mouths for drinking or over their bodies for bathing. Nostr...

• Atom I INTRODUCTION Water Molecule A water molecule consists of an oxygen atom and two hydrogen atoms, which are attached at an angle of 105°.

  spontaneously break apart and change, or decay, into other atoms. Unlike electrons, which are fundamental particles, protons and neutrons are made up of other, smaller particles called quarks. Physicists know of six different quarks.Neutrons and protons are made up of up quarks and down quarks —two of the six different kinds of quarks. The fanciful names of quarks have nothing to do with their properties; the names are simply labels to distinguish one quark from another. Quarks are unique amo...

• Columbus (Ohio) - geography.

  replica of the flagship of Christopher Columbus, built to commemorate the 500th anniversary of his voyage. The city also supports a symphony orchestra and opera andballet companies. A leading attraction is the Columbus Zoo. Noted for its success in breeding rare animals, the zoo has extensive exhibits with natural-like habitat, including a huge coral reefaquarium. The Franklin Park Conservatory, built in 1895, contains in its large, glass-enclosed space duplicates of many of the world’s ecosyste...

• Yukon Territory - Geography.

  Tourism is the second most important private sector industry in the Yukon. Visitors come to fish, hunt, enjoy the rugged scenery, and see the historic buildings andcreeks associated with the gold rush. Some marten, lynx, muskrat, wolverine, and other fur-bearing animals are still trapped, but the Yukon plays a minor role in Canadian fur production. The Yukon’s manufacturing industries consist almost exclusively of some mineral refining, printing, and sawmilling. Several hydroelectric plants gene...

• Yukon Territory - Canadian History.

  Tourism is the second most important private sector industry in the Yukon. Visitors come to fish, hunt, enjoy the rugged scenery, and see the historic buildings andcreeks associated with the gold rush. Some marten, lynx, muskrat, wolverine, and other fur-bearing animals are still trapped, but the Yukon plays a minor role in Canadian fur production. The Yukon’s manufacturing industries consist almost exclusively of some mineral refining, printing, and sawmilling. Several hydroelectric plants gene...

• Ocean and Oceanography.

  of sediment. When studied in sedimentary core samples, which can represent many millions of years of deposits, they provide a detailed and continuous history of theearth’s environmental changes. The record is particularly informative for the most recent 2 million to 5 million years, during which major fluctuations in global climatehave occurred. Successive ice ages can be traced by the relative scarcity or abundance of the shells of warm-water and cold-water diatoms in various layers of asedimen...

• Ocean and Oceanography - Geography.

  of sediment. When studied in sedimentary core samples, which can represent many millions of years of deposits, they provide a detailed and continuous history of theearth’s environmental changes. The record is particularly informative for the most recent 2 million to 5 million years, during which major fluctuations in global climatehave occurred. Successive ice ages can be traced by the relative scarcity or abundance of the shells of warm-water and cold-water diatoms in various layers of asedimen...

• British Columbia - Geography.

  hemlock, Douglas fir, Sitka spruce, and various cedars, grows rapidly in the mild, wet climate and produces the largest trees in Canada. In the dry lowlands of thesouthern and central interior, ponderosa and lodgepole pines, aspen, and bunchgrass are characteristic. Spruce dominates the Prince George region. Prairie grasses andstands of aspen are found in the northeastern corner of the province. At elevations higher than about 1,800 m (about 6,000 ft), an alpine vegetation of shrubs, mosses,and...

• British Columbia - Canadian History.

  hemlock, Douglas fir, Sitka spruce, and various cedars, grows rapidly in the mild, wet climate and produces the largest trees in Canada. In the dry lowlands of thesouthern and central interior, ponderosa and lodgepole pines, aspen, and bunchgrass are characteristic. Spruce dominates the Prince George region. Prairie grasses andstands of aspen are found in the northeastern corner of the province. At elevations higher than about 1,800 m (about 6,000 ft), an alpine vegetation of shrubs, mosses,and...

• Venezuela - country.

  Venezuela has six navigable rivers. Of the thousand or more streams in the country, the majority flow into the Orinoco. The Orinoco flows east across central Venezuelaand drains approximately four-fifths of the total area of the country. With the tributaries—the Apure, Meta, and Negro rivers—it forms the outlet into the Atlantic Oceanfor the waters of much of the interior of Colombia, as well as of inland Venezuela. F Climate The climate of Venezuela is tropical on the Llanos and along the coas...

• Nunavut - Canadian History.

  The Arctic Lands is a complex geological area that is centered on the Arctic Ocean. It includes coastal plains, plateaus, and mountains. Coastal plains and plateaus arefound in the western Northwest Territories section of the Arctic Lands, such as on Victoria Island, which is mostly a large, flat plateau. In striking contrast to theserelatively gentle landscapes, the eastern Nunavut section of the Arctic Lands is dominated by a jagged chain of ice-covered mountains. The mountains on EllesmereIsl...

• Earth (planet).

  Milky Way to complete one revolution around the Galaxy’s center. Earth’s axis of rotation is inclined (tilted) 23.5° relative to its plane of revolution around the Sun. This inclination of the axis creates the seasons and causes the height of the Sun in the sky at noon to increase and decrease as the seasons change. The Northern Hemisphere receives the most energy from the Sun when it is tiltedtoward the Sun. This orientation corresponds to summer in the Northern Hemisphere and winter in the S...

• Earth (planet) - astronomy.

  Milky Way to complete one revolution around the Galaxy’s center. Earth’s axis of rotation is inclined (tilted) 23.5° relative to its plane of revolution around the Sun. This inclination of the axis creates the seasons and causes the height of the Sun in the sky at noon to increase and decrease as the seasons change. The Northern Hemisphere receives the most energy from the Sun when it is tiltedtoward the Sun. This orientation corresponds to summer in the Northern Hemisphere and winter in the S...

• Atom - chemistry.

  Atoms have several properties that help distinguish one type of atom from another and determine how atoms change under certain conditions. A Atomic Number Each element has a unique number of protons in its atoms. This number is called the atomic number (abbreviated Z). Because atoms are normally electrically neutral,the atomic number also specifies how many electrons an atom will have. The number of electrons, in turn, determines many of the chemical and physical properties ofthe atom. The ligh...

• Québec - Geography.

  facilities. Tributaries south of the St. Lawrence include the Richelieu, the Saint-François, and the Chaudière rivers, which are only a few hundred kilometers long. TheRimouski and Matane rivers, also south of the St. Lawrence, are popular areas for recreation and salmon fishing. In the Canadian Shield, the longest rivers are theRupert, Eastmain, Grande Baleine, and La Grand-Rivière, which is the site of a huge hydroelectric complex. C Coastlines Québec has two systems of saltwater coastline. O...

• Québec - Canadian History.

  facilities. Tributaries south of the St. Lawrence include the Richelieu, the Saint-François, and the Chaudière rivers, which are only a few hundred kilometers long. TheRimouski and Matane rivers, also south of the St. Lawrence, are popular areas for recreation and salmon fishing. In the Canadian Shield, the longest rivers are theRupert, Eastmain, Grande Baleine, and La Grand-Rivière, which is the site of a huge hydroelectric complex. C Coastlines Québec has two systems of saltwater coastline. O...

• Togo - country.

  corn, millet, and sorghum. The leading export crops are coffee, cotton, groundnuts, and cacao. Livestock, chiefly sheep and goats, are raised on the northern plateau.Fish are caught in Togo’s rivers and in the Gulf of Guinea. B Mining and Manufacturing Togo is a leading producer of phosphates, which are by far the country’s most significant mineral product. In 2004, 400,000 metric tons of phosphate rock were mined.Industrial activity is limited but growing. The leading manufactures include ceme...

• San Diego - geography.

  Qualcomm Stadium is the home of the San Diego Chargers, playing major league football. PETCO Park is the home of the San Diego Padres, playing major leaguebaseball. Major sporting events in the city include a professional golf tournament in February, hydroplane races on Mission Bay in late summer, and the Holiday Bowlpostseason college football game in December. VI ECONOMY The total value of all the goods and services produced in San Diego make it one of the most powerful economies in the worl...

• Gabon - country.

  government is engaged in preservation and reforestation programs. The fish catch in 2005 was 43,941 metric tons. C Mining Mining has developed rapidly since Gabon’s independence in 1960. Annual production of extremely high-grade manganese ore, from Moanda in the southeast, was1,090,000 metric tons in 2004. The rich deposits of iron ore located at Mekambo and Bélinga in the northeast have reserves estimated at more than 500 million metrictons. Exploitation of the iron ore has been hampered by th...

• Zambia - country.

  The Livingstone Museum, at Livingstone, has a collection relating to the archaeology and natural history of southern Africa. The Institute for African Studies of theUniversity of Zambia publishes studies relating to central Africa. IV ECONOMY The wealth of Zambia is based largely on mining in the rich copper belt, and downturns in copper prices have severely damaging economic consequences. Someprocessing and manufacturing has been started since independence, and during the 1970s attempts were...

• Cameroon - country.

  seminomadic herders of the north. Cattle, goats, and fowl are the most commonly raised animals. B Forestry and Fishing Timber is traditionally one of Cameroon’s most valuable exports, consisting mainly of mahogany, ebony, and teak. The timber cut in 2006 amounted to 11.4 million cu m(401 million cu ft). Most of the fish caught in Cameroon come from the country’s rivers and lakes and are consumed locally. However, deep-sea fishing activity isincreasing, especially from the port of Douala. Some 1...

• Barbados - country.

  Barbados is served by a public library system centered in Bridgetown. B Culture The culture of Barbados combines English institutions, which evolved through more than three centuries of English rule, with a folk culture of African origin. Because ofits English traditions, Barbados is sometimes called “Little England.” Cricket has traditionally been the national game, and the island has produced some of the sport’sgreatest players. Water sports including surfing, swimming, snorkeling, and sailin...

• Botswana - country.

  at birth was 50.2 years, also a significant improvement. The urban population of Botswana has increased rapidly, from 18 percent of the total in 1981 to 51 percent in 2003. Gaborone, the capital, is the largest city and mainbusiness center. Other business centers are Francistown, Selebi-Pikwe, Molepolole, Kanye, and Serowe. Botswana received its name from the country’s principal ethnic group, the Tswana. Other ethnic groups include the Kgalagadi, Kalanga, and Basarwa. There are also asmall numbe...

• Weather.

  hours, and the snow can be much deeper in places where the wind piles it up in drifts. Extraordinarily deep snows sometimes accumulate on the upwind side ofmountain slopes during severe winter storms or on the downwind shores of large lakes during outbreaks of polar air. VI WIND Wind is the horizontal movement of air. It is named for the direction from which it comes—for example, a north wind comes from the north. In most places near theground, the wind speed averages from 8 to 24 km/h (from 5...

• Somalia - country.

  A Agriculture Livestock raising is the principal occupation in Somalia. The size of livestock herds began to recover in the mid-1990s after falling during the country’s civil war. Sheepand goats are the most numerous livestock, with smaller numbers of cattle. The principal crops grown are corn, sorghum, sugarcane, cassava, and bananas. B Forestry and Fishing While most wood is cut for fuel, Somalia’s major forestry export products before the 1990s were frankincense and myrrh. Fish is an import...

• Venus (planet) - astronomy.

  level winds circle the planet at 360 km/h (225 mph), making a complete rotation in only four days. These winds are said to super-rotate because they travel muchfaster than the rotation of the planet itself. These high-speed winds cover the planet completely, blowing toward the west at virtually every latitude from equator topole. The motions of descending probes, however, have shown that the bulk of Venus’s tremendously dense atmosphere, closer to the planet’s surface, is almoststagnant. From th...

• Republic of Singapore - country.

  Singaporeans of Chinese and Indian ancestry live in small, nuclear families. Housing favors smaller families, as most units consist of small apartments in high-risebuildings. Western clothing is common, and foods reflect the Chinese, Malay, and Indian origins of the people. D Social Issues Since Singapore became an independent state in 1965, government policies have brought orderliness and efficiency to the country. Examples are supplanting slum andsquatter areas with high-rise public housing p...