144 résultats pour "hémisphères"

• Australia - country.

  itself forms most of the border between New South Wales and Victoria. Considerable lengths of the Murray, Darling, and Murrumbidgee rivers are navigable during thewet seasons. The central plains region, also known as the Channel Country, is interlaced by a network of rivers. During the rainy season these rivers flood the low-lying countryside,but in dry months they become merely a series of water holes. The Victoria, Daly, and Roper rivers drain a section of the Northern Territory. In Queensland...

• Australia - Geography.

  itself forms most of the border between New South Wales and Victoria. Considerable lengths of the Murray, Darling, and Murrumbidgee rivers are navigable during thewet seasons. The central plains region, also known as the Channel Country, is interlaced by a network of rivers. During the rainy season these rivers flood the low-lying countryside,but in dry months they become merely a series of water holes. The Victoria, Daly, and Roper rivers drain a section of the Northern Territory. In Queensland...

• Le développement du cerveau

• Définition de austral

• Un enseignement déséquilibré

• Buys-Ballot Christophorus Hendrick , 1817-1890, né à Kloetinge (Pays-Bas), météorologiste néerlandais.

• jet-stream.

• Season - astronomy.

• Le climat de la zone chaude et humide

  NOTRE PLANÈTE LE CLIMAT DE LA ZONE Le climat tropical L'absence de saison froide et une saison humide d' au moins 3 mois - la mousson - caractérisent le climat tropical. L'hiver est sec , l' été est pluvieux et dure 3 mois dans un climat tropical sec, 7 mois au moins dans un climat tropical hum ide . La moyenne des températures du mois le plus froid est de 18 °c au moins ; mais en saison sèche et pendant la nuit, la tempé...

• Guericke (Otto von), 1602-1686, né à Magdebourg, physicien allemand, bourgmestre de Magdebourg de 1646 à 1681.

• Guericke, Otto von - physicien.

• Le cerveau : LE CENTRE DE CONTRÔLE (Travaux Personnels Encadrés – Médecine & Santé – TS)

  PROCESSUS DE RÉCUPÉRATION Toutes ces protections n'empêchent malheureusement pas les accidents, mais même en pareils cas, le cerveau montre une faculté de récupération remarquable. Schématiquement, si un neurone est détruit, son voisin s'adapte et devient capable d'effectuer le travail à sa place. C'est ce que l'on observe lorsque qu'une personne victime d'une attaque cérébrale se retrouve partiellement paralysée ou perd l'usage de la parole mais r...

• LA PSYCHOBIOLOGIE

  2 élu sénateur en 1879. En 1870, Gustav Fritsch et Edward Hitzig démontrent que, chez le chien, la stimulation électrique de zones précises du cerveau cause des mouvements déterminés, et que la moitié gauche du cerveau commande les mouvements de la moitié droite du corps, tandis que la moitié droite commande ceux de la moitié gauche. Wernicke propose une carte des fonctions du cerveau, un peu sur le modèle de Gall, en soulignant toutefois que ne sont localisables que celles qui jouent un rôle d...

• conifères.

• écliptique.

• BIOSPHÈRE LES BIOMES GÉNÉRALITÉS La surface de la Terre n'est pas uniforme, mais

  2 régions les plus arides de la Terre. Dans les déserts chauds, les températures diurnes dépassent 38 °C et il ne pleut jamais, car les masses d’air en mouvement ont perdu toute la vapeur d’eau qu’elles contenaient. Les savanes sont des prairies tropicales plus ou moins arides, où des arbres poussent parfois çà et là. Ces étendues herbacées plus ou moins arborées caractérisent les régions tropicales et subtropicales où la température est constamment élevée, et où il existe des variations saison...

• alizé adj.

• biogéographie - encyclopédie.

  nord-ouest du continent nord-américain notamment. Les espèces végétales généralement sempervirentes (à feuilles persistantes) sont de grande taille (sapin de Douglas, séquoia géant, eucalyptus). La faune aquatique est nombreuse. Les steppes tempérées apparaissent quand la quantité des précipitations est trop faible pour permettre la croissance des arbres. En revanche, le tapis graminéen est particulièrement développé. L'exemple de la prairie américaine l'illustre bien. À ce type de...

• Article de presse: Bandoung ou la mort du complexe d'infériorité

  pour détourner la colère des Afro-Asiatiques vers d'autres puissances alors coloniales, France et Pays-Bas notamment, et pourisoler l'Union soviétique de ses alliés potentiels du tiers-monde. Ces arrière-pensées ne peuvent être négligées. Mais ce qui frappa surtout les témoins, ce fut la maîtrise de soi et la maturitédont firent preuve la plupart des porte-parole de ce concile des pauvres. Ce que craignaient bien des responsables et observateurs occidentaux, à commencer par le chef de la d...

• météorologie.

  Cyclone ElenaCette photographie du cyclone Elena a été prise en 1985 depuis la navette spatiale Discovery, avec un objectif de 70 mm. Le cyclonese trouve dans l'hémisphère Nord, c'est pourquoi l'air circule dans le sens inverse des aiguilles d'une montre autour des bassespressions de l'œil du cyclone.NASA/Science Source/Photo Researchers, Inc. On fait également appel à l’aviation pour obtenir des observations en haute altitude, notamment quand des cyclones — ou typhons — menacent des zones habit...

• Saturne - astronomie.

  diamètres très variés, allant de 5.10 -6 m à environ 10 m. Ainsi, malgré leur apparence impressionnante, les anneaux de Saturne sont extrêmement minces — leur épaisseur n'excédant pas 1,5 km — et ne contiennent que très peu de matière. La séparation apparente entre les anneaux A et B est appelée division de Cassini, du nom de l'astronome français Jean-Dominique Cassini, qui l’a découverte auXVII e siècle. Un trou moins visible au sein de l’anneau A est appelé division de Encke, en hommage à l’as...

• Marque du territoire du chasseur primitif, cadastre en ?gypte ou ? Rome, document de localisation des terres nouvelles gard? secret au XVIe si?cle, la carte a toujours ?t? un instrument de puissance ?conomique et politique aux mains de ses utilisateurs.

  xérothermique (indice) Le langage graphique et les modes de représentation.La carte est une image destinée à communiquer une information géographique à un public varié. Aussi les modes de représentations'appuient-ils sur trois analyses : celle de l'information géographique à cartographier, celle du langage graphique, fondé sur la sémiologie(science des signes), et celle du destinataire de la carte (élève, grand public, chercheur). À partir de tests et d'études sur la façon dont lacarte est per...

• forêt.

  C'est une forêt relativement mal connue. Les forêts galeries, le long des fleuves, tels les Varzeas de l'Amazone ou les marécages — gri-gri de Guyane, poto-poto de Côted'Ivoire ou swamp forest du Nigeria — en constituent les faciès floristiques et fauniques les plus riches. Cette forêt dense, appelée aussi forêt pluvieuse, est entourée deforêts dites sèches ou de mousson là où les pluies sont moins abondantes et où apparaît une saison sèche plus ou moins longue. Alors le caractère sempervirent s...

• forêt (faune & Flore).

  C’est une forêt relativement mal connue. Les forêts galeries, le long des fleuves, tels les Varzeas de l’Amazone ou les marécages — gri-gri de Guyane, poto-poto de Côted’Ivoire ou swamp forest du Nigeria — en constituent les faciès floristiques et fauniques les plus riches. Cette forêt dense, appelée aussi forêt pluvieuse, est entourée deforêts dites sèches ou de mousson là où les pluies sont moins abondantes et où apparaît une saison sèche plus ou moins longue. Alors le caractère sempervirent s...

• Fur Trade in North America - Canadian History.

  Injured by the competition from the North West Company, the Hudson’s Bay Company changed its methods in the late 18th century and began extending its operationsinland. After a period of intense and often violent conflict, the two companies merged in 1821 under the charter of the Hudson’s Bay Company. The trade monopoly andpower to govern that had been originally given to Hudson’s Bay in 1670 were extended to all British-held territory west of Rupert’s Land. The company dominated mostof present-d...

• SYSTÈME SOLAIREGÉNÉRALITÉSOn entend par « Système solaire » une famille de corps célestes formée par l'étoileSoleil et par une multitude de corps distribués autour d'elle.

  2 auraient échappé jusqu'ici à nos observations. La génération actuelle d'instruments astronomiques n'est pas en mesure d'identifier des corps de dimensions planétaires aux confins du domaine gravitationnel du Soleil. Les astronomes pensent que, s'il y avait une autre planète au-delà des orbites de Neptune et de Pluton, celle-ci pourrait être découverte grâce aux perturbations induites par sa force d'attraction. Vers la fin des années 80, analysant les trajectoires des sondes interplanét...

• Africa - history.

  Africa’s other major mountainous regions occur at the northern and southern fringes of the continent. The Atlas Mountains, a system of high ranges, extend for 2,200 km(1,400 mi) across Morocco, Algeria, and Tunisia, roughly parallel to the northern coast. These ranges enclose a number of broad inland basins and plateaus. In the west, theHigh (or Grand) Atlas contains Toubkal (4,165 m/ 13,665 ft), the highest peak of the system. Toward the east, the Atlas consists of two parallel ranges: the Tell...

• Africa.

  The highest elevations in Africa are found in the various ranges of East Africa. After Kilimanjaro, the next highest peaks are Mount Kenya (5,199 m/17,057 ft), north ofKilimanjaro in central Kenya; Margherita Peak (5,109 m/ 16,762 ft) in the Ruwenzori Range on the border between Uganda and the Democratic Republic of the Congo(DRC); Ras Dashen (4,620 m/ 15,157 ft) in the Ethiopian Highlands of northern Ethiopia; Mount Meru (4,565 m/ 14,977 ft), close to Kilimanjaro in Tanzania; and MountElgon (4,...

• Astronomy - astronomy.

  Telescopes may use either lenses or mirrors to gather visible light, permitting direct observation or photographic recording of distant objects. Those that use lenses arecalled refracting telescopes, since they use the property of refraction, or bending, of light ( see Optics: Reflection and Refraction ). The largest refracting telescope is the 40-in (1-m) telescope at the Yerkes Observatory in Williams Bay, Wisconsin, founded in the late 19th century. Lenses bend different colors of light by d...

• Neptune (planet) - astronomy.

  The gaseous atmosphere of Neptune contains hydrogen, helium, and about 3 percent methane. It extends about 5,000 km (about 3,000 mi) above the planet’s ocean.Light reflected from Neptune’s deep atmosphere is blue, because the atmospheric methane absorbs red and orange light but scatters blue light. In 1998 astronomersalso identified molecules of methyl in Neptune’s atmosphere. Methyl molecules each contain one carbon atom and three hydrogen atoms. Methyl molecules are knownas hydrocarbon radical...

• Atlantic Slave Trade.

  members of the planters’ society. Through most of the years of the Atlantic trade, prices for Africans remained favorable in relation to the price of the crops theyproduced. They were, thus, the best economic solution for plantation owners seeking inexpensive labor. The Atlantic slave trade began as a trickle in the 1440s and grew slowly through the 17th century. By 1700, 25,000 slaves, on average, were crossing the Atlantic everyyear. After 1700 the trade grew much more rapidly to a peak in the...

• John Quincy Adams.

  man of my whole country.” When President Thomas Jefferson requested Senate approval of his treaty for the purchase of the French colony of Louisiana, Adams was the only New EnglandFederalist to vote in favor of it. He realized that the power and influence of his own New England would be reduced if the vast territory were added to the nation, but hewas convinced that the national interest would best be served by the purchase of Louisiana ( see Louisiana Purchase). Adams again broke with his New...

• John Quincy Adams

  man of my whole country.” When President Thomas Jefferson requested Senate approval of his treaty for the purchase of the French colony of Louisiana, Adams was the only New EnglandFederalist to vote in favor of it. He realized that the power and influence of his own New England would be reduced if the vast territory were added to the nation, but hewas convinced that the national interest would best be served by the purchase of Louisiana ( see Louisiana Purchase). Adams again broke with his New...

• Conservation.

  cancers, Hodgkin’s disease and leukemia. Unfortunately, human activities have greatly reduced biodiversity around the world. The 20th century encompasses one of the greatest waves of extinction, orelimination of species, to occur on the planet. The greatest threat to biodiversity is loss of habitat as humans develop land for agriculture, grazing livestock, industry,and habitation. The most drastic damage has occurred in the tropical rain forests, which cover less than seven percent of the Earth’...

• Uruguay (country) - country.

  Freedom of religion is guaranteed by the constitution of Uruguay. Three-quarters of the people belong to the Roman Catholic Church. There are also sizable Protestantand Jewish congregations. The official language is Spanish, which in Uruguay has been influenced by Italian vocabulary and pronunciation. C Education Uruguay has one of the highest rates of literacy in Latin America, at 98.2 percent of the adult population. Six years of primary education is compulsory, and Uruguay isone of the few n...

• Moon - astronomy.

  B Volcanic Features Maria, domes, rilles, and a few craters display indisputable characteristics of volcanic origin. Maria are plains of dark-colored rock that cover approximately 40 percent ofthe Moon's visible hemisphere. The maria formed when molten rock erupted onto the surface and solidified between 3.16 billion and 3.96 billion years ago. This rockresembles terrestrial basalt, a volcanic rock type widely distributed on Earth, but the rock that formed the maria has a higher iron content an...

• Butterflies and Moths - biology.

  The smallest butterflies are certain blues that have wingspans of a mere 0.7 cm (0.25 in). The largest are the female giant birdwings of Papua New Guinea, whichmeasure up to 30 cm (12 in) across. Moths range in size from tiny Microlepidoptera, several groups of small moths with wings no more than 0.16 cm (0.06 in) across, togiant silk moths, such as the atlas moth, which may exceed 30 cm (12 in) in wingspan. IV REPRODUCTION AND LIFE CYCLE Butterflies locate potential mates by sight, identifyin...

• Chile - country.

  D Plant and Animal Life The indigenous plant life of Chile varies according to climatic zone. Plant life in the northern region includes brambles and cactus and has little variety. Here, theAtacama provides one of the best examples on Earth of an absolute desert. The more humid Central Valley supports several species of cacti, espino (a thorny shrub),grasses, and the Chilean pine, which bears edible nuts. Dense rain forests are located south of Valdivia with laurel, magnolia, false beech, and v...

• New York (city) - geography.

  The Bronx is the fourth largest and the northernmost of the five boroughs, and the only one on the American mainland. Even so, it is surrounded by water on threesides: Long Island Sound on the east, the Harlem and East rivers on the south, and Hudson River on the west. Encompassing 109 sq km (42 sq mi), it had 1,332,650inhabitants in 2000. Largely residential, the Bronx includes dozens of vibrant neighborhoods. Fieldston is particularly elegant, with great stone houses set among spacious lawns a...

• California - geography.

  The Basin and Range province is an arid area of mountain ranges, basins, and deserts. In California it is represented primarily by parts of the Great Basin and SonoranDesert sections. Within the Great Basin lies Death Valley, whose lowest elevation, 86 m (282 ft) below sea level, is the lowest point in the Western Hemisphere. TheSonoran Desert section is characterized by numerous flat plains separated by low but rugged ranges. It includes the extensive Mojave, or Mohave, Desert. Also in thisprov...

• California - USA History.

  The Basin and Range province is an arid area of mountain ranges, basins, and deserts. In California it is represented primarily by parts of the Great Basin and SonoranDesert sections. Within the Great Basin lies Death Valley, whose lowest elevation, 86 m (282 ft) below sea level, is the lowest point in the Western Hemisphere. TheSonoran Desert section is characterized by numerous flat plains separated by low but rugged ranges. It includes the extensive Mojave, or Mohave, Desert. Also in thisprov...

• Museum.

  History museums are dedicated to promoting a greater appreciation and knowledge of history and its importance to understanding the present and anticipating thefuture. They range from historic sites and small historic house museums to large, encyclopedic institutions such as the Smithsonian’s National Museum of AmericanHistory in Washington, D.C. Many cities and states have historical societies that operate museums or historic sites. History museums usually collect a wide range ofobjects, includi...

• Africa.

  The highest elevations in Africa are found in the various ranges of East Africa. After Kilimanjaro, the next highest peaks are Mount Kenya (5,199 m/17,057 ft), north ofKilimanjaro in central Kenya; Margherita Peak (5,109 m/ 16,762 ft) in the Ruwenzori Range on the border between Uganda and the Democratic Republic of the Congo(DRC); Ras Dashen (4,620 m/ 15,157 ft) in the Ethiopian Highlands of northern Ethiopia; Mount Meru (4,565 m/ 14,977 ft), close to Kilimanjaro in Tanzania; and MountElgon (4,...

• Africa - Geography.

  The highest elevations in Africa are found in the various ranges of East Africa. After Kilimanjaro, the next highest peaks are Mount Kenya (5,199 m/17,057 ft), north ofKilimanjaro in central Kenya; Margherita Peak (5,109 m/ 16,762 ft) in the Ruwenzori Range on the border between Uganda and the Democratic Republic of the Congo(DRC); Ras Dashen (4,620 m/ 15,157 ft) in the Ethiopian Highlands of northern Ethiopia; Mount Meru (4,565 m/ 14,977 ft), close to Kilimanjaro in Tanzania; and MountElgon (4,...