541 résultats pour "wats"

• 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...

• Turkey - country.

  has a general elevation of 900 to 1,500 m (3,000 to 5,000 ft) above sea level. The eastern highlands region is the most mountainous and rugged portion of Turkey; Mount Ararat (Ağrı Da ğı) is the highest peak in the country at 5,165 m (16,945ft). Many Christians and Jews believe it to be the same Mount Ararat mentioned in the Bible as the place where Noah’s ark came to rest. The eastern highlands are thesource for both the Tigris (Dicle) and Euphrates (Fir āt)—two of southwestern Asia’s principal...

• Michigan - geography.

  The interior location of Michigan in the northern part of North America results in a continental climate, characterized by four definite seasons with moist, mild to hotsummers and snowy, cold winters. Winds off of Lakes Michigan and Superior in winter create heavy snow accumulations in nearby areas. The tempering effects of LakeMichigan account for the presence of the state’s famous fruit-growing belt along the lake’s shore. Since the water is colder than the land in spring, the westerly windspa...

• Michigan - USA History.

  The interior location of Michigan in the northern part of North America results in a continental climate, characterized by four definite seasons with moist, mild to hotsummers and snowy, cold winters. Winds off of Lakes Michigan and Superior in winter create heavy snow accumulations in nearby areas. The tempering effects of LakeMichigan account for the presence of the state’s famous fruit-growing belt along the lake’s shore. Since the water is colder than the land in spring, the westerly windspa...

• Saturn - astronomy.

  measurements of the magnetic field made by the Voyager space probes in the 1980s. Additional Cassini findings reported in March 2007 suggested that particles originating from geysers on the moon Enceladus may provide a partial explanation for thechange. The neutral gas particles become electrically charged and are captured by Saturn’s magnetic field, forming a disk of hot, ionized gas around the planet’sequator. The charged particles interact with the magnetic field and slow down the rotation of...

• 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...

• Sewage Disposal.

  greater load on the piping system and the treatment plant. The amount of storm-water drainage to be carried away depends on the amount of rainfall as well as on the runoff or yield of the watershed ( see Drainage). A typical metropolitan area discharges a volume of wastewater equal to about 60 to 80 percent of its total daily water requirements, the rest being used for washingcars and watering lawns, and for manufacturing processes such as food canning and bottling. B Composition The composi...

• Nova Scotia - Geography.

  summer. Nova Scotia receives an average of more than 1,140 mm (45 in) of rain annually, with the Atlantic shore receiving 1,400 mm (55 in) or more. Most of the provincereceives about 1,900 mm (about 70 in) of snow, and considerable winter precipitation comes in the form of rain or ice storms. The average temperature in January, thecoldest month, is generally about -4°C (about 25°F) near the coast and somewhat colder toward the interior. The average temperature in July, the hottest month, isabout...

• Nova Scotia - Canadian History.

  summer. Nova Scotia receives an average of more than 1,140 mm (45 in) of rain annually, with the Atlantic shore receiving 1,400 mm (55 in) or more. Most of the provincereceives about 1,900 mm (about 70 in) of snow, and considerable winter precipitation comes in the form of rain or ice storms. The average temperature in January, thecoldest month, is generally about -4°C (about 25°F) near the coast and somewhat colder toward the interior. The average temperature in July, the hottest month, isabout...

• Hazardous Wastes.

  A Source Reduction The best way to eliminate hazardous wastes is not to generate them in the first place. For example, improvements have been made in the production of integratedcircuits: The toxic chlorinated hydrocarbons commonly used in the 1970s were replaced in the 1980s by less toxic glycol ethers and in the 1990s by low-toxicity estersand alcohols. B Recycling Recycling is the recovery or reuse of usable materials from waste. About 5 percent of hazardous waste in the United States is re...

• Plant - biology.

  B1 Vacuoles Vacuoles are membrane-bound cavities filled with cell sap, which is made up mostly of water containing various dissolved sugars, salts, and other chemicals. B2 Plastids Plastids are types of organelles, structures that carry out specialized functions in the cell. Three kinds of plastids are important here. Chloroplasts contain chlorophyllsand carotenoid pigments; they are the site of photosynthesis, the process in which light energy from the sun is fixed as chemical energy in the b...

• Chemistry - chemistry.

  parts of oxygen by weight, which is a ratio of about 1 to 8, regardless of whether the water came from the Mississippi River or the ice of Antarctica. In other words, acompound has a definite, invariable composition, always containing the same elements in the same proportions by weight; this is the law of definite proportions. Many elements combine in more than one ratio, giving different compounds. In addition to forming water, hydrogen and oxygen also form hydrogen peroxide.Hydrogen peroxide h...

• Amazon (river) - geography.

  5,000 indigenous groups remain today in Peru, but few are untouched by the outside world.Alison Wright/Corbis The Amazon watershed includes the largest and wettest tropical plain in the world. Heavy rains drench much of the densely forested lowland region throughout the year butespecially between January and June. Seasonal variation in rainfall is reflected by the width, rate of flow, and discharge volume of the river. During the months of maximumprecipitation, broad areas traversed by the Amazo...

• Planetary Science - astronomy.

  III ORIGINS AND COMPOSITIONS OF PLANETS Astronomers believe that planetary systems are formed of elemental materials that were created in the interiors of giant stars. Some of this material comes from giantstars that shed material into space as they age. Most of the matter to form planets, however, comes from stars that explode as supernovas and spread debris enrichedwith the heavier chemical elements into space. According to the currently accepted views, the most likely first stage in the evo...

• Bird. I INTRODUCTION Bird, animal with feathers and wings. Birds are the only

  B Physical Adaptations for Flight The internal body parts of all birds, including flightless ones, reflect the evolution of birds as flying creatures. Birds have lightweight skeletons in which many of themajor bones are hollow. A unique feature of birds is the furculum, or wishbone, which is comparable to the collarbones of humans, although in birds the left and rightportions are fused together. The furculum absorbs the shock of wing motion and acts as a spring to help birds breathe while they...

• Bird - biology.

  B Physical Adaptations for Flight The internal body parts of all birds, including flightless ones, reflect the evolution of birds as flying creatures. Birds have lightweight skeletons in which many of themajor bones are hollow. A unique feature of birds is the furculum, or wishbone, which is comparable to the collarbones of humans, although in birds the left and rightportions are fused together. The furculum absorbs the shock of wing motion and acts as a spring to help birds breathe while they...

• Coral Reef.

  sensitive to particles of mud or sediment settling on them, which means that corals rarely grow close to rivers or other sources of sediment. In the sea, light is filteredout by depth, so reef-building corals can only grow in relatively shallow water. Even in the clearest oceans few reef-building corals grow below a depth of 80 to 100 m(260 to 328 ft). Although corals need nutrients, they cannot thrive in areas where there are large amounts of nutrients. Typically, microscopic organisms in the p...

• Fungus - biology.

  Many fungi can reproduce by the fragmentation of their hyphae. Each fragment develops into a new individual. Yeast, a small, single-celled fungus, reproduces bybudding, in which a bump forms on the yeast cell, eventually partitioning from the cell and growing into a new yeast cell. V CLASSIFICATION OF FUNGI Scientists have long disagreed about how to classify fungi, and the classification systems are still developing. The first description of fungi was published in 1729 byItalian botanist Pier...

• Digestive System.

  The stomach, located in the upper abdomen just below the diaphragm, is a saclike structure with strong, muscular walls. The stomach can expand significantly to storeall the food from a meal for both mechanical and chemical processing. The stomach contracts about three times per minute, churning the food and mixing it with gastricjuice. This fluid, secreted by thousands of gastric glands in the lining of the stomach, consists of water, hydrochloric acid, an enzyme called pepsin, and mucin (the...

• Cell (biology) - biology.

  proteins, or other proteins required by the cell. While relatively simple in construction, prokaryotic cells display extremely complex activity. They have a greater range of biochemical reactions than those found in theirlarger relatives, the eukaryotic cells. The extraordinary biochemical diversity of prokaryotic cells is manifested in the wide-ranging lifestyles of the archaebacteria andthe bacteria, whose habitats include polar ice, deserts, and hydrothermal vents—deep regions of the ocean un...

• Bacteria - biology.

  A2 b Bacterial Killers Some dramatic infectious diseases result from exposure to bacteria that are not part of our normal bacterial community. Cholera, one of the world’s deadliest diseasestoday, is caused by the bacterium Vibrio cholerae . Cholera is spread in water and food contaminated with the bacteria, and by people who have the disease. After entering the body, the cholera bacteria grow in the intestines, often along the surface of the intestinal wall, where they secrete a toxin (poiso...

• Delaware - geography.

  D Climate Delaware has generally hot and humid summers and mild winters. D1 Temperature In July, average daytime temperatures are usually in the upper 20°s to lower 30°sC (80°sF) or even higher. But because summer nights tend to be cooler than thedays, July averages are about 24°C (about 75°F). In addition, onshore sea breezes can reduce daytime temperatures along the coast by 3 to 6 Celsius degrees (5 to 10Fahrenheit degrees). January averages range from -1°C (31°F) at Newark, in the north, t...

• Delaware - USA History.

  D Climate Delaware has generally hot and humid summers and mild winters. D1 Temperature In July, average daytime temperatures are usually in the upper 20°s to lower 30°sC (80°sF) or even higher. But because summer nights tend to be cooler than thedays, July averages are about 24°C (about 75°F). In addition, onshore sea breezes can reduce daytime temperatures along the coast by 3 to 6 Celsius degrees (5 to 10Fahrenheit degrees). January averages range from -1°C (31°F) at Newark, in the north, t...

• 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...

• Belgium - country.

  European Union (EU) directives aimed at improving Belgium’s environmental conditions concern water treatment and water quality, both significant issues in such anindustrial center. Before these directives were issued, the Meuse River, a major source of drinking water, had become polluted from steel production wastes. Otherrivers were polluted with animal wastes and fertilizers. However, Belgium failed to meet EU targets set for the early 2000s for protecting its rivers from farm pollutionand for...

• Afghanistan - country.

  D Climate Most of Afghanistan has a subarctic mountain climate with dry and cold winters, except for the lowlands, which have arid and semiarid climates. In the mountains and afew of the valleys bordering Pakistan, a fringe effect of the Indian monsoon, coming usually from the southeast, brings moist maritime tropical air in summer.Afghanistan has clearly defined seasons: Summers are hot and winters can be bitterly cold. Summer temperatures as high as 49°C (120°F) have been recorded in thenorth...

• Space Exploration - astronomy.

  to produce 250,000 newtons (56,000 lb) of thrust. The Germans launched thousands of V-2s carrying explosives against targets in Britain and The Netherlands. Whilethey did not prove to be an effective weapon, V-2s did become the first human-made objects to reach altitudes above 80 km (50 mi)—the height at which outer spaceis considered to begin—before falling back to Earth. The V-2 inaugurated the era of modern rocketry. A2 Early Artificial Satellites During the years following World War II, the...

• Uzbekistan - country.

  E Environmental Issues The evaporation of the Aral Sea is one of the worst ecological disasters in the world. The Aral has shrunk so much that it now holds only about one-fifth the volume ofwater it held in 1960. The shrinkage is due to irrigation withdrawals from the Amu Darya and Syr Darya, a practice that began on a massive scale in the early 1960s aspart of the Soviet Union’s ill-conceived drive to increase cotton yields in Central Asia. Growing cotton in the naturally arid and saline soil...

• Switzerland - country.

  formation over higher elevations. The wind reverses direction about sundown and moves down the valley as a cool downdraft. The foehn, which occurs during the wintermonths, is a dry and relatively warm airflow that is drawn northward over the Alps. The foehn can quickly melt snow and ice, increasing the risk of mudslides andavalanches. D Natural Resources Waterpower is the chief natural resource of Switzerland. The principal source of water is runoff from the considerable annual precipitation th...

• Yangtze - Geography.

  A Agriculture and Industry Today about 400 million people, or about one-third of the population of China, live in the Yangtze Basin. Many are engaged in agriculture. The basin contributes nearlyhalf of China’s crop production, although only one-quarter of the basin is arable. The most fertile areas for farming are the Sichuan Basin, the plains between theYangtze and its tributary the Han, and the plains of the lower basin. In all about 40 percent of the cereals, more than 30 percent of the cott...

• Flower - biology.

  insects. The sepals unfurl as the flower opens and often resemble small green leaves at the flower’s base. In some flowers, the sepals are colorful and work with thepetals to attract pollinators. E Variations in Structure Like virtually all forms in nature, flowers display many variations in their structure. Most flowers have all four whorls—pistil, stamens, petals, and sepals. Botanists callthese complete flowers. But some flowers are incomplete, meaning they lack one or more whorls. Incomplet...

• New Brunswick - Geography.

  Grand Lake, the largest lake in New Brunswick, is in the lowlands, east of Fredericton. Most other lakes are located in the northern and southwestern parts of NewBrunswick. D Climate New Brunswick has a continental climate that is moderated by maritime influences in the coastal areas. As a result, coastal regions are slightly warmer in the winter andslightly cooler in the summer than are interior regions. Annual temperature variations are large, with the January mean usually at least 25 to 28°C...

• New Brunswick - Canadian History.

  Grand Lake, the largest lake in New Brunswick, is in the lowlands, east of Fredericton. Most other lakes are located in the northern and southwestern parts of NewBrunswick. D Climate New Brunswick has a continental climate that is moderated by maritime influences in the coastal areas. As a result, coastal regions are slightly warmer in the winter andslightly cooler in the summer than are interior regions. Annual temperature variations are large, with the January mean usually at least 25 to 28°C...

• North Dakota - geography.

  Bismarck, the growing season averages 134 days, as the average date of the last killing frost is May 11 and that of the first killing frost is September 22. The length ofthe growing season drops to about 110 days in the northerly reaches of the state. The long periods of summer sunshine at this latitude, providing as much as 16 hoursof daylight in summer, help crops to mature quickly, thus compensating somewhat for the relatively short growing season. Temperatures in the north are, on the averag...

• North Dakota - USA History.

  Bismarck, the growing season averages 134 days, as the average date of the last killing frost is May 11 and that of the first killing frost is September 22. The length ofthe growing season drops to about 110 days in the northerly reaches of the state. The long periods of summer sunshine at this latitude, providing as much as 16 hoursof daylight in summer, help crops to mature quickly, thus compensating somewhat for the relatively short growing season. Temperatures in the north are, on the averag...

• HAENDEL - WATER MUSIC (allegro)

• Desert - geography.

  irrigation from rivers or wells. Such transformations of deserts are not without problems. Evaporation of the irrigation water results in the accumulation of salt on thesurface soil, eventually rendering it useless for further crop production. By tapping reservoirs of fossil water deep beneath the desert, humans are, in effect, miningwater. Once this water is gone, it is irreplaceable. Burning and overgrazing of semiarid lands on the periphery of deserts can irreversibly damage the plants thatco...

• Desert - Geography.

  irrigation from rivers or wells. Such transformations of deserts are not without problems. Evaporation of the irrigation water results in the accumulation of salt on thesurface soil, eventually rendering it useless for further crop production. By tapping reservoirs of fossil water deep beneath the desert, humans are, in effect, miningwater. Once this water is gone, it is irreplaceable. Burning and overgrazing of semiarid lands on the periphery of deserts can irreversibly damage the plants thatco...

• Ice Ages.

  B Future Ice Ages The record of previous glacial activity is the best indicator for future ice ages. Scientists examine the evidence for the numerous 100,000-year glacial-interglacial cycleswithin the present ice age to attempt a forecast of future ice ages. Since all previous ice ages lasted tens of millions of years, our present ice age will likely continue fora considerable amount of time. Each glaciation begins slowly and may take 80,000 years or more to reach its maximum extent. A rapid me...

• Metabolism (chemistry) - biology.

  nearly perfect balance. Although much remains to be revealed about metabolic processes, biochemists now agree that regulatory, or rate-limiting, enzymes figure largely in the reactionsinvolved ( see Enzyme). Affecting metabolic pathways at the earliest steps, each enzyme molecule has a specific, or active, site that matches, or “fits,” its particular substrate—the compound with which the enzyme forms a product. The precision with which rate-limiting enzymes and substrates join to set off a parti...

• Houston - geography.

  Prominent historical and cultural institutions include the Civic Center Complex, located in the central business district. The complex is composed of the George R. BrownConvention Center; the Wortham Center, which is the home of the Houston Grand Opera and the Houston Ballet; and the Jesse H. Jones Hall for Performing Arts, whichis the home of the Houston Symphony. The nearby Alley Theatre houses a professional repertory acting company. Among other local professional performance groupsare the Ma...

• Mountain Climbing.

  teeth on one side, and a straight, flat, metal blade called an adze on the other. Ice axes have many uses. One of the most common is to help the climber stay balanced on steep slopes. The climber swings the axe with a short, quick movement to lodge the pick in snow or ice, creating a secure anchor. If a climber should slip and beginsliding down a snowfield, a self-arrest can be performed by turning face down on the snow and burying the pick in the snow surface. The climber’s weight over the...

• Industrial Revolution I INTRODUCTION Industrial Revolution, widespread replacement of manual labor by machines that began in Britain in the 18th century and is still continuing in some parts of the world.

  The most important advance in iron production occurred in 1784 when Englishman Henry Cort invented new techniques for rolling raw iron, a finishing process thatshapes iron into the desired size and form. These advances in metalworking were an important part of industrialization. They enabled iron, which was relativelyinexpensive and abundant, to be used in many new ways, such as building heavy machinery. Iron was well suited for heavy machinery because of its strength anddurability. Because of t...

• Industrial Revolution .

  The most important advance in iron production occurred in 1784 when Englishman Henry Cort invented new techniques for rolling raw iron, a finishing process thatshapes iron into the desired size and form. These advances in metalworking were an important part of industrialization. They enabled iron, which was relativelyinexpensive and abundant, to be used in many new ways, such as building heavy machinery. Iron was well suited for heavy machinery because of its strength anddurability. Because of t...

• Amphibians.

  AN AMPHIBIAN’S LIFE Amphibians that live in cold places spend most of their time trying to keep wet and warm. In hot places,they try to keep wet and cool and usually come out only at night. During the day, they stay under rocksor logs or in the ground. Amphibians hibernate (become inactive) during cold winters. They become inactive in hot places during the summer. Almost all grown-up amphibians are meat eaters. Frogs and salamanders have sticky tongues. They flickout their tongues to catch ins...

• Leaf - biology.

  The mesophyll, sandwiched between the upper and lower epidermis, consists of many thin-walled cells that are usually arranged in two layers. The palisade layer is next to the upper epidermis. It consists of cylindrical cells that are packed closely together. Next to the palisade layer and making up most of the thickness of the leaf bladeis the spongy layer. The spongy layer consists of roundish cells that are packed loosely together and have numerous air spaces between them. In most plants t...

• Map - geography.

  Relief MapRelief maps are three-dimensional models of the terrain in an area; on them, color and scale are used to indicate geographicalfeatures rather than simply to delineate political boundaries. Because of this feature, relief maps are extensively used in engineeringand the military. This map shows portions of Alaska and northwestern Canada.United States Geological Survey Among the most important of the special-purpose maps are hydrographic and aviation charts. Hydrographic charts are used f...

• Camping.

  Commercial campgrounds serve as campsites for RV and car campers on the outskirts of national and state parks and along highways throughout North America.Owners of commercial campgrounds charge campers on a daily or weekly basis, and provide campsites equipped with hookups for electricity and water. They may alsoprovide such amenities as showers, laundry facilities, or a swimming pool. Many commercial campgrounds belong to a club or network that allows its members toreserve campsites in advance....