Climatic zones of the Pacific Ocean. Classification
Geographical position. The Indian Ocean is located entirely in the Eastern Hemisphere between Africa - in the west, Eurasia - in the north, the Sunda Islands and Australia - in the east, Antarctica - in the south. The Indian Ocean in the southwest communicates widely with the Atlantic Ocean, and in the southeast with the Pacific. The coastline is poorly dissected. There are eight seas in the ocean, there are large bays. There are relatively few islands. The largest of them are concentrated near the coasts of the continents.
Bottom relief. As in other oceans, the bottom topography in the Indian Ocean is complex and varied. Among the uplifts at the bottom of the ocean stands out mid-ocean ridge system diverging to the northwest and southeast. The ridges are characterized by rifts and transverse faults, seismicity and underwater volcanism. Between the ridges lie numerous deep sea basins. The shelf generally has a small width. But it is significant off the coast of Asia.
Mineral resources. There are significant oil and gas deposits in the Persian Gulf, off the coast of Western India and off the coast of Australia. Large reserves of ferromanganese nodules have been found at the bottom of many basins. Sedimentary rock deposits on the shelf contain tin ores, phosphorites, and gold.
Climate. The main part of the Indian Ocean lies in the equatorial, subequatorial and tropical zones., only the southern part covers high latitudes, up to the subantarctic. The main feature of the ocean's climate is the seasonal monsoon winds in its northern part., which is heavily influenced by land. Therefore, in the northern part of the ocean there are two seasons of the year - a warm, quiet, sunny winter and a hot, cloudy, rainy, stormy summer. South of 10°S dominated by the southeast trade wind. To the south, in temperate latitudes, a strong and steady westerly wind blows. The amount of precipitation is significant in the equatorial zone - up to 3000 mm per year. There is very little precipitation off the coast of Arabia, in the Red Sea and the Persian Gulf.
currents. In the northern part of the ocean, the formation of currents is influenced by the change of monsoons, which rebuilds the system of currents according to the seasons of the year: summer monsoon - in the direction from west to east, winter - from east to west. In the southern part of the ocean, the most significant are the South Equatorial Current and the Western Wind Current.
Water properties. The average surface water temperature is +17°С. The slightly lower average temperature is explained by the strong cooling effect of the Antarctic waters. The northern part of the ocean warms up well, is deprived of the influx of cold waters and is therefore the warmest. In summer, the water temperature in the Persian Gulf rises to +34°C. In the southern hemisphere, the temperature of the waters gradually decreases with increasing latitude. The salinity of surface waters in many areas is higher than average, and in the Red Sea it is especially high (up to 42 ppm).
organic world. It has a lot in common with the Pacific Ocean. The species composition of fish is rich and varied. Sardinella, anchovy, mackerel, tuna, dolphin, sharks, flying fish live in the northern part of the Indian Ocean. In southern waters - notothenia and white-blooded fish; there are cetaceans and pinnipeds. The organic world of the shelf and coral reefs is especially rich. Thickets of algae border the coast of Australia, South Africa, islands. There are large commercial accumulations of crustaceans (lobsters, shrimps, krill, etc.). In general, the biological resources of the Indian Ocean are still poorly studied and underutilized.
natural complexes. The northern part of the ocean lies in tropical zone. Under the influence of the surrounding land and monsoon circulation, several aquatic complexes are formed in this belt, differing in the properties of water masses. Especially sharp differences are noted in the salinity of the waters.
In the equatorial zone The temperature of surface waters hardly changes with the seasons of the year. Above the numerous uplifts of the bottom and near the coral islands in this belt, a lot of plankton develops, and bioproductivity increases. Tunas live in such waters.
Zonal complexes of the southern hemisphere in general terms, they are similar in natural conditions to similar belts of the Pacific and Atlantic oceans.
Economic use. The biological resources of the Indian Ocean have been used by the inhabitants of the coasts since time immemorial. And until now, handicrafts of fish and other seafood retain an important role in the economy of many countries. However, the natural resources of the ocean are used to a lesser extent than in other oceans. Biological productivity of the ocean as a whole is low, it increases only on the shelf and the continental slope.
Chemical resources ocean waters are still poorly used. On a large scale, desalination of salt water is being carried out in the countries of the Middle East, where there is an acute shortage of fresh water.
Among mineral resources oil and gas deposits are identified. In terms of their reserves and production, the Indian Ocean ranks first in the World Ocean. Coastal-marine placers contain heavy minerals and metals.
Important transport routes pass through the Indian Ocean. In the development of shipping, this ocean is inferior to the Atlantic and Pacific, but in terms of oil transportation it surpasses them. The Persian Gulf is the main oil export region of the world, from here a large cargo flow of oil and oil products begins. Therefore, systematic monitoring of the state of the aquatic environment and its protection from oil pollution are necessary in this region.
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Climatic zones of the Pacific Ocean. Classification.
The zoning of the ocean is the main regularity in the distribution of all properties in the waters of the World Ocean, which manifests itself in the change of physiographic belts to a depth of 1500-2000 m. But this regularity is most clearly observed in the upper active layer of the ocean to a depth of 200 m.
The Soviet scientist D.V. Bogdanov divided the ocean into regions that are homogeneous in terms of the natural processes prevailing in them. The classification of the climatic zones of the World Ocean proposed by him is currently the most popular.
D.V. Bogdanov in the World Ocean identified (from north to south) the following climatic zones (natural zones), which are in good agreement with the natural zones of land.
Note: Dear visitors, hyphens in long words in the table are set for the convenience of mobile users - otherwise the words will not wrap and the table will not fit on the screen. Thanks for understanding!
|
Climatic zone (natural zone) of the World Ocean |
Distinctive feature |
Compliance with the natural land area |
|
Northern Polar (Arctic) - SP |
Coincides with the Arctic Basin of the Arctic Ocean |
Arctic zone (ice desert) |
|
Northern sub-polar (subarctic) - SSP |
Covers areas of the ocean within seasonal variations of the ice edge |
Subarctic zone (tundra and forest-tundra) |
|
North temperate - SU |
Water temperature 5-15°C |
Temperate zone (taiga, broad-leaved forests, steppe) |
|
Northern subtropical - SST |
Coincides with quasi-stationary areas of high pressure (Azores and Hawaiian maxima) |
Dry and humid subtropics and northern desert regions |
|
Northern tropical (trade wind) - ST |
It is located between the average annual northern and southern boundaries of the trade wind |
Tropical deserts and savannas |
|
Equatorial - E |
Slightly shifted to the north along with the thermal equator, water temperature 27-29°C, salinity lowered |
Moist equatorial forests |
|
Southern tropical (trade wind) - UT |
Savannahs and tropical deserts |
|
|
Southern subtropical - UST |
Appears less distinctly than the northern |
Dry and wet subtropics |
|
South temperate - SU |
Located between the subtropical convergence and the Antarctic convergence |
Temperate, treeless zone |
|
Southern subpolar (subantarctic) - USP |
Situated between the Antarctic Convergence and the Antarctic Divergence |
Subpolar land zone |
|
South polar (Antarctic) - UP |
Includes mostly shelf seas around Antarctica |
Ice zone of Antarctica |
Of the climatic zones presented in the table, the Pacific Ocean accounts for almost all, except for the northern polar (Arctic).
Within the identified climatic zones, regional differences are observed due to the characteristics of the underlying surface (warm and cold currents), the proximity of the continents, depths, wind systems, etc. In the western part of the Pacific Ocean, marginal seas are usually distinguished as physiographic regions, in the eastern intensive upwelling (rise of deep waters to the surface of the ocean).
Most of the surface of the Pacific Ocean, approximately between 40° north latitude and 42° south latitude, is located in the equatorial, tropical and subtropical climate belts.
Consider the climatic zones of the Pacific Ocean in more detail.
Climatic zones of the Pacific Ocean. Characteristic, description.
Northern subpolar (subarctic) climatic zone of the Pacific Ocean.
Geographical position: The northern subpolar climatic zone of the Pacific Ocean occupies most of the Bering and Okhotsk Seas approximately between 60° and 70° N. latitude. sh. . It is determined by the limits of seasonal ice distribution - between the winter and summer boundaries of their distribution.
In winter, large masses of ice form within the belt, and salinity increases. In summer, the ice melts, desalinating the water. In summer, water warms up only in a thin surface layer, while an intermediate layer of water that has cooled in winter remains at a depth.
Bioproductivity: The northern subpolar climatic zone of the Pacific Ocean occupies the vast shelves of the Bering and Okhotsk Seas, rich in commercial fish, invertebrates and marine animals. The high bioproductivity of the region is associated, first of all, with the relatively shallow depths of the water area - nutrients are not lost at great depths, but are actively included in the cycle of organic substances.
North temperate climate zone of the Pacific Ocean.
Geographical position: The northern temperate climatic zone of the Pacific Ocean is located between the areas of formation of cold subarctic and warm subtropical and tropical waters approximately between 35 and 60 ° N. sh.
| The areas of the Japan and Yellow Seas and the Gulf of Alaska are distinguished. | |
| Water temperature: | In winter near the coast it can drop to 0°С, in summer it rises to 15-20°С (up to 28°С in the Yellow Sea). |
| Salinity: | In the northern half of the water area 33%o, in the southern half it is close to the average - 35‰. |
| Prevailing winds: | Western. The western part of the belt is characterized by monsoon circulation, sometimes typhoons come here. |
| Currents: |
|
Description of the Pacific climate zone: In the west of the belt, the warm Kuroshio Current and the cold Kuril Current (Oyashio) interact. From the streams formed with mixed water, the North Pacific Current is formed, which occupies a significant part of the water area and carries huge masses of water and heat from west to east under the influence of the westerly winds prevailing here. Ice forms only in limited inland areas of shallow seas (for example, in the northern part of the Sea of Japan). In winter, vertical thermal convection of waters develops with the participation of intense wind mixing: cyclonic activity is active in temperate latitudes. In the north of the northern temperate climatic zone of the Pacific Ocean, there is the Aleutian minimum of atmospheric pressure, well pronounced in winter, in the south - the northern part of the Hawaiian maximum.
Bioproductivity: The high content of oxygen and nutrients in the water ensures a relatively high bioproductivity, and its value in the northern part of the belt (subpolar waters) is higher than in the southern part (subtropical waters).
Northern subtropical climate zone of the Pacific Ocean.
Geographical position: The northern subtropical climatic zone of the Pacific Ocean is located between the zone of westerly winds of temperate latitudes and the trade winds of equatorial-tropical latitudes. The belt is represented by a relatively narrow band approximately between 23 and 35°N. sh., stretching from Asia to North America.
Description of the Pacific climate zone: The northern subtropical climate zone of the Pacific Ocean is characterized by low rainfall, mostly clear weather, relatively dry air, high atmospheric pressure and high evaporation. These features are explained by the stable air stratification, in which the vertical air movements are attenuated.
North tropical climate zone of the Pacific Ocean
Geographical position: The northern tropical belt of the Pacific Ocean stretches from the shores of Mexico and Central America to the Philippine Islands and Taiwan, continues to the shores of Vietnam and Thailand in the South China Sea. Lies between 20 and 30 ° N. sh.
Description of the Pacific climate zone: In a significant part of the belt, the trade winds of the Northern Hemisphere and the Northern Trade Wind Current dominate. The monsoon circulation is developed in the western part. The northern tropical belt of the Pacific Ocean is characterized by high temperatures and salinity.
Equatorial climate zone of the Pacific Ocean.
Geographical position: The equatorial climatic zone of the Pacific Ocean is represented quite widely. It is located on both sides of the equator at approximately 20°N. sh. up to 20°S sh., between the northern and southern tropical belts.
| Physical-geographic regions: | Panama region, Australo-Asian Seas, New Guinea Sea, Solomon Sea. |
| Water temperature: | The equatorial water masses are well warmed up by the sun, their temperature changes seasonally by no more than 2° and is 27 - 28°C. |
| Salinity: | 36-37‰ |
| Prevailing winds: |
|
| Currents: | Equatorial countercurrent - from west to east of the ocean. |
| Bioproductivity: | The belt is characterized by relatively high bioproductivity. |
Description of the Pacific climate zone: Intense thermal air convection develops here, and heavy rains fall throughout the year. The bottom topography and geological structure are most complex in the west and relatively simple in the east. This is the area of attenuation of the trade winds in both hemispheres. The equatorial climatic zone of the Pacific Ocean is characterized by constantly warm waters of the surface layer, complex horizontal and vertical water circulation, a large amount of precipitation, and a wide development of eddy movements.
Southern tropical climate zone of the Pacific Ocean.
Geographical position: The southern tropical climatic zone of the Pacific Ocean occupies a vast expanse of water between Australia and Peru from 20 to 30 ° S. sh.
Description of the Pacific climate zone: The eastern part of the southern tropical climatic zone of the Pacific Ocean has a relatively simple bottom topography. Several thousand large and small islands are located in the western and middle parts. Hydrological conditions are determined by the South Equatorial Current. The salinity of the water is lower than in the northern tropical climate zone, especially in summer due to heavy rains. The western part of the belt is influenced by the monsoon circulation. Tropical hurricanes are not uncommon here. They often originate between the islands of Samoa and Fiji and move west to the coast of Australia.
Southern subtropical climate zone of the Pacific Ocean.
Geographical position: The southern subtropical climatic zone of the Pacific Ocean stretches in a winding strip of variable width from southeastern Australia and Tasmania to the east; covers most of the Tasman Sea, the area of New Zealand, the space between 30 and 40 ° S. sh.; closer to the coast of South America, it descends to somewhat lower latitudes and approaches the coast between 20 and 35 ° S. sh.
Description of the Pacific climate zone: The deviation of the belt boundaries from the latitudinal strike is associated with the circulation of surface waters and the atmosphere. The axis of the southern subtropical climatic zone in the open part of the Pacific Ocean is the subtropical convergence zone, where the waters of the South Equatorial Current and the northern jet of the Antarctic Circumpolar Current converge. The position of the convergence zone is unstable, depends on the season and changes from year to year, however, the main processes typical of the belt are constant: the lowering of air masses, the formation of a high pressure area and marine tropical air, and the salinization of waters.
South temperate climate zone of the Pacific Ocean.
Geographical position: The northern boundary of the belt is close to 40-45°S. sh., and the south passes about 61-63 ° S. sh., i.e., along the northern border of the distribution of sea ice in September.
Description of the Pacific climate zone: The southern temperate climatic zone is the area of dominance of western, northwestern and southwestern winds, stormy weather, significant cloudiness, low winter and summer temperatures of surface waters and intensive transfer of surface water masses to the east.
For the waters of this climatic zone of the Pacific Ocean, the change of seasons is already characteristic, but it comes later than on land, and is not so pronounced. The salinity of the waters of the southern climatic zone of the Pacific Ocean is lower than that of the tropical ones, since atmospheric precipitation, rivers flowing into these waters, and icebergs entering these latitudes have a desalination effect.
Southern subpolar (subantarctic) climatic zone of the Pacific Ocean.
Geographical position: The subantarctic climatic zone of the Pacific Ocean has no clear boundaries. The southern border is the northern part or border of the Southern Ocean (Western Wind Current), in the north, Tristan da Cunha and the island of Amsterdam with a temperate maritime climate are sometimes referred to as subantarctic islands. Other sources place the subantarctic boundary between 65-67° and 58-60° south latitude.
Description of the Pacific climate zone: The belt is characterized by strong winds, precipitation is about 500 mm per year. There is more precipitation in the northern part of the belt.
The water area of the South subpolar climatic zone of the Pacific Ocean is especially wide in the area of the Ross Sea, which penetrates deep into the massif of the Antarctic continent. In winter, the waters are covered with ice. The largest islands are Kerguelen, Prince Edward, Crozet, the New Zealand Subantarctic Islands, Heard and McDonald, Macquarie, Estados, Diego Ramirez, the Falklands, South Georgia and the South Sandwich Islands, etc., which lie in the zone of oceanic meadows covered with grasses, lichens , less often - shrubs.
South polar (Antarctic) climatic zone of the Pacific Ocean.
Geographical position: The Antarctic climatic zone of the Pacific Ocean is located directly off the coast of Antarctica below 65 ° Yu. sh. The width of the belt is only 50-100 km.
Air temperature:
In the middle of summer (January), off the coast of Antarctica, the air temperature does not rise above 0 ° C, in the Weddell and Ross seas - up to -6 ° C, but at the northern border of the climatic zone, the air temperature warms up to + 12 ° C.
In winter, the difference in air temperature at the northern and southern boundaries of the south polar climatic zone of the Pacific Ocean is much more pronounced. At the southern borders in the coastal region, the thermometer drops to -30 ° C, at the northern borders of the belt, the air temperature does not drop to negative values and remains at the level of 6 - 7 ° WITH.
Description of the Pacific climate zone:
Antarctica is the most severe climatic region of the Earth with low air temperatures, strong winds, snow storms and fogs.
Within the Pacific Ocean, the Antarctic climatic zone is quite extensive. In the Ross Sea, the waters of the ocean go far beyond the Antarctic Circle, almost to 80 ° S. sh., and taking into account ice shelves - even further. To the east of McMurdo Bay, the cliff of the Ross Ice Shelf (Great Ice Barrier) stretches for hundreds of kilometers.
The water masses of the south polar climatic zone of the Pacific Ocean are characterized by an abundance of floating ice, as well as ice that forms huge ice expanses. The scale of these covers depends on the time of year, and at the peak it reaches 500-2000 km in width. In the Southern Hemisphere, in areas of polar water masses, sea ice enters temperate latitudes much further than in the Northern Hemisphere. The salinity of the polar water masses is low, since floating ice has a strong desalination effect.
In this article, we examined the climatic zones of the Pacific Ocean. Read more: Climate of the Pacific. Cyclones and anticyclones. baric centers.
The Pacific (or Great) Ocean occupies 1/3 of the Earth's surface and almost half of the area and more than half of the volume of the World Ocean. This is the largest, the warmest(according to surface water temperature) and The most deep from all oceans. The ocean is located in all hemispheres Land and is surrounded by Eurasia and Australia to the west, North and South America to the east, and Antarctica to the south. Its border with the Arctic Ocean runs along the Bering Strait, with the Atlantic - along the narrowest point of the Drake Passage, and with the Indian - along a conditional line (all seas between the islands of the Malay Archipelago belong to the Pacific Ocean, and south of Australia - all waters east of the 145th Meridian East)
Coastline relatively straight off the coast of North and South America and strongly dissected off the coast of Eurasia. Fjord and abrasion types of shores predominate. In tropical latitudes in the west, the shores are coral, in places with barrier reefs. Near Antarctica, the shores are formed by ice shelves. In the western part of the ocean there are many archipelagos and individual islands - in terms of their number and area, the Pacific Ocean ranks first. Most of the marginal seas are also located here.
Bottom relief The Pacific Ocean is very complex. The shelf is relatively narrow, especially off the coast of North and South America (several tens of kilometers), while off the coast of Eurasia it measures hundreds of kilometers. Deep-sea trenches are located in the peripheral parts of the ocean (25 of the 35 trenches of the World Ocean with a depth of more than 5 km and all four trenches with a depth of more than 10 km). Large uplifts, individual mountains and ridges divide the ocean floor into basins. In the southeast is the East Pacific Rise, which is part of the system of mid-ocean ridges.
Most of the ocean is on one lithospheric plate. Deep-sea trenches and island arcs are confined to the zones of its interaction with continental plates; "Fiery Pacific Ring"(a chain of active volcanoes and epicenters of terrestrial and underwater earthquakes that cause tsunamis), as well as deposits of ore minerals.
Mineral resources. Large reserves of ferromanganese nodules are concentrated at the bottom of the ocean. Oil and gas deposits have been discovered on the shelves off the coast of Asia and South America. Alluvial deposits of gold and tin were found in loose deposits near the coast. Phosphorite deposits are confined to the zones of deep water rise near the western tropical coasts of South America.Climate. Most of the Pacific Ocean lies in the equatorial, subequatorial and tropical zones. Here the air temperature is +16...+24 °C all year round. In the north of the ocean in winter, it drops below 0 ° C, off the coast of Antarctica, this temperature is constant. Trade winds dominate in tropical latitudes, westerly winds dominate in temperate latitudes, and monsoons off the coast of Eurasia. Strong storms and typhoons often occur. The maximum amount of precipitation (about 3000 mm) falls in the western part of the equatorial "belt, the minimum - in the eastern regions between the equator and the southern tropic (about 100 mm).Near Antarctica, sea ice persists all year round. In the northern part - only in winter. Antarctic icebergs are observed up to 40 ° S. sh.
currents. There are two huge rings of water movement in the ocean. The northern ring includes the Northern Equatorial, Kuroshio, North Pacific and California currents; South - South Equatorial, East Australian, West Winds and Peruvian currents. They have a significant impact on the redistribution of heat in the ocean, on the nature of the adjacent land. For example, trade winds carry warm water from the eastern parts of the ocean to the western parts, so at low latitudes the western part of the ocean is much warmer than the eastern part. In middle and high latitudes, on the contrary, the eastern parts of the ocean are warmer than the western ones.organic world. In terms of the number of species and biomass, the organic world of the Pacific Ocean is richer than in other oceans (the fauna has about 100 thousand species, and phytoplankton - 380). Organic life is especially rich in equatorial-tropical latitudes, in areas of coral reefs. The northern part of the ocean is characterized by a variety of salmon species. Fishing in the ocean accounts for almost half of the world's catch. Main commercial species: salmon, cod, flounder, perch. The main fishing areas are upwelling areas off the coast of America (the waters off the coast of South America between 4 and 23 ° S are especially productive), areas of interaction between warm and cold waters, and western shelves.Natural complexes. In the Pacific Ocean there are all natural belts, except for the north polar one, they are elongated in the latitudinal direction.In the Northern Subpolar Belt, there is an intensive circulation of waters, so they are rich in fish. The Northern temperate zone is characterized by the interaction of warm and cold water masses. The oxygen-rich waters are full of a variety of organisms.
The western part of the Northern subtropical belt is warm, the eastern part is cold. The waters are poorly mixed, and the number of plankton and fish is small.
In the Northern Tropical Belt there are many single islands and archipelagos, and the Northern Trade Wind is being formed. Water productivity is low. In the equatorial belt, a complex interaction of various currents is observed, at the boundaries of which ascending flows are formed and biological productivity increases. The most rich in life are the shelves of the Sunda Islands, aquatic complexes of coral reefs.
The natural belts of the Southern Hemisphere are similar to the northern ones, but differ in the composition of organisms.
Continents and oceans as the largest natural complexes
Africa.Geographical position. Africa is the second largest continent after Eurasia (occupies one-fifth of the land or about 30 million sq. km).
The mainland is based on the ancient African-Arabian platform, excluding the Atlas and Cape mountains. Therefore, a flat relief prevails here with heights from 500 to 1000 m. An example is the interior of Africa with high plains dissected by river valleys. Low-lying plains are quite rarely located in the coastal zones of Africa.
East Africa is a modern rift zone stretching from the Red Sea through the Ethiopian Highlands to the mouth of the Zambezi River for 6000 km.
As a result, flat-topped blocky mountains and the deepest depressions arose, in many of which there are lake basins - narrow and deep. Volcanic massifs meet here - Mount Kilimanjaro (5895 m) and Kenya (5199 m).
In the extreme north and extreme south of the mainland, folded mountainous areas adjoin the platform. The Atlas Mountains in the northwest have a height of up to 4000 m and are part of the Alpine Himalayan mountain belt. They are characterized by high seismicity. The Cape Mountains in the south are older and lower. These are unique revived folded mountains. In the southeast of the mainland, the Dragon Mountains are formed by lava plateaus up to 4000 m high.
Climate. The position in the equatorial zone and between the Northern and Southern tropics led to a hot climate on the mainland. Average summer temperatures are above 20 °C, average winter temperatures are up to 8 °C. Africa's climates vary in the amount and pattern of precipitation. Their maximum number is observed in the area of the Congo River and the Gulf of Guinea - up to 3000 mm per year; on the windward slopes of mountains up to 9000 mm of precipitation per year; in tropical latitudes, less than 300 mm of precipitation falls annually.
dominates the Congo Basin constant humid and hot equatorial climate: precipitation throughout the year, air temperature 26-28 °С. Monsoon subequatorial climate forms north and south up to 20 latitudes: in summer, in each hemisphere, the equatorial monsoon brings a large amount of precipitation; in winter, tropical air creates dry, hot weather. The amount of precipitation decreases from west to east, since the east of Africa is separated by uplifts of the relief.
tropical climate characterized by dry weather throughout the year. In summer the air temperature is +40 °С, in winter +18 °С. Relative air humidity is not higher than 25%. In the tropical climatic zone of the Northern Hemisphere, there is a huge desert of the world - the Sahara. Within the tropical zone, in the southern, narrower part of the mainland, more precipitation falls. Air masses from the Indian and Atlantic oceans meet here, as a result of their interaction, clouds are formed and precipitation falls. The climate of coastal deserts with a cool climate and cool summers is typical for the western coast of the tropics - the Namib Desert. The cold ocean current has its influence here. There is a so-called temperature inversion - there is not sufficient condensation of a large amount of water vapor, there is little precipitation, mostly frequent fogs and dews. The east coast in the southern tropics is characterized by a hot, humid tropical climate. The eastern slopes of the Drakensberg Mountains block the path of moisture-saturated air masses, and heavy rainfall falls there.
Northwest Africa lies within subtropical mediterranean climate with a seasonal change of air masses (tropical in summer, moderate in winter). Therefore, summer here is dry and hot, winter is warm and humid. In southeast Africa, the climate of the monsoonal subtropics is characterized by rainier summers. In winter, the Cape Mountains prevent the penetration of moist westerly winds into the territory, and there is little rainfall.
Inland waters. The development of the African river system depends on the relief and climate of the mainland. Africa is relatively poor in land waters; there are vast arid spaces on its territory. There is a dense river network in those areas where there is a large amount of precipitation.
The rivers of Africa are mostly rain-fed. The deepest river is the Congo. A significant part of its basin is located in the equatorial climatic zone. The longest river in Africa and the entire Earth - the Nile (6671 km) originates in the East African Plateau. In the upper reaches, it is full-flowing, since it receives numerous tributaries. In the lower reaches, flowing through the Libyan desert, the river loses a lot of water to evaporation and seepage into the ground.
The Congo is the second largest river in Africa, the second most abundant river, after the Amazon. A significant part of its basin is located in the zone of constant high moisture. In the upper and lower reaches it is very rapids. Niger, Zambezi, Senegal, Orange also flow through the mainland. The Zambezi is home to the largest Victoria Falls, 120 m high and 1800 m wide.
The lakes of Africa are located mainly in the eastern part of the mainland, their origin is associated with tectonic faults. They have a narrow elongated shape and are quite deep - Tanganyika (1470 m), Nyasa (706 m). Lake Victoria was formed in a trough of the earth's crust. The regime of the shallow Lake Chad, located in the south of the Sahara, depends on the amount of precipitation, and during the drought period its territory is halved.
natural areas. The flat relief, the position between the tropics, the uneven distribution of precipitation led to a pronounced latitudinal zonality on the mainland. Natural zones, like climatic zones, are located symmetrically to the equator and almost coincide in the Northern and Southern Hemispheres.
The wet region of the equator and the vast area of the Congo River cover moist evergreen equatorial forests.
Savannah - a type of steppe, which is characterized by a combination of grass cover with single trees. These are vast expanses of Africa, occupying 40% of the territory. There are dry and wet seasons of the year. As a result, soils are more fertile and are called reddish brown. The vegetation of the savannas is represented by cereals and low trees (up to 25 m) - acacias, fan palms, baobabs. Savannahs are rich in plant foods, so there are many large herbivores: giraffes, zebras, antelopes, buffaloes, rhinos, hippos. Among predators there are crocodiles, jackals, cheetahs, lions.
Tropical deserts. The soils of tropical deserts are primitive, do not contain mineral salts, their origin is due to the arid climate. These soils are called lateritic. Within this natural zone is the largest desert in the world, the Sahara, and in the southwest, the Namib Desert.
In deserts, vegetation is rather sparse and tends to retain moisture by reducing the area of evaporation from the surface of the plant. Most species have a powerful root system that penetrates deep into the soil, are leafless and covered with wax, and the leaves are replaced by thorns - these are leafless cereals, tamarisks.
An exception to the lifeless African deserts are oases. These are green islands of natural and artificial origin. Most of the oases in the Sahara are man-made - the main crop in them is the date palm.
Desert animals adapt to their environment. Artiodactyls (antelopes) have to travel great distances in search of food. Camels are hardy animals that can go without water for a long time. There are also many reptiles here.
Subtropical hardwood evergreen forests located on the northwestern and southeastern outskirts of the mainland. The proximity of the ocean forms the seasonality of precipitation, hot summers and warm winters. Therefore, the flora here is much richer. The soils are brown and fertile. They grow evergreen deciduous and coniferous forests.
South America. Geographical position. Two continents - South and North America - form a single part of the world under the common name America. These continents are interconnected by the Isthmus of Panama, through which in 1920 the navigable Panama Canal was dug, connecting the Pacific and Atlantic oceans. South America is located in the Western Hemisphere and is washed by the waters of the Pacific (in the west) and Atlantic (in the north and east) oceans. The area of the mainland is approximately 18 million km2. In its shape, South America is similar to a triangle, tapering to the south.
Relief and geological structure. The relief of South America is represented by plains and plateaus in the east and mountain ranges in the west of the mainland. The relief of the eastern part is based on the ancient South American platform. Large low-lying plains formed on it - the Amazonian, Orinokskaya, La Platskaya, composed of strata of marine and continental sediments. The Brazilian and Guiana Highlands, 500 to 2500 m high, are confined to the shields (raised sections of the platform).
In the west of the mainland, the Andes, or Andean Cordillera, stretch for 9000 km from north to south, separating the rest of the continent from the Pacific Ocean. This is a folded region of Alpine age; is a continuation of the North American Cordillera and consists of parallel ranges. The highest peak is Mount Aconcagua (6960 m), as well as the volcano Cotopaxi (5897 m) and Mount Chimborazo (6267 m).
Between the ranges are the Central Andean highlands and plateaus. The mountain-building processes in the Andes have not ended, so earthquakes and volcanic eruptions are frequent here.
Climate. The geographic location and configuration of the mainland determine how much heat it receives throughout the year. South America is the wettest continent on Earth. Trade winds bring a lot of moisture from the Atlantic Ocean. The Andes block the way for air masses from the Pacific Ocean.
Most of the Amazonian lowland and the northeast coast of the mainland are located in equatorial belt. The air temperature during the year is +25-28 °С. The amount of precipitation is from 1500 to 3500 mm, in the foothills of the Andes - up to 7000 mm.
subequatorial belt The northern and southern hemispheres are connected on the east coast, fringing the equatorial climatic zone. There is a seasonality in the distribution of precipitation. A large number of them - 2000 mm - falls in the summer. The rainy season in the Northern Hemisphere is from May to December, in the Southern Hemisphere from December to May. Air temperature +25 °С. Winter comes with the advent of tropical continental air. Precipitation is practically non-existent; air temperature +20 °C.
Tropical climate zone South America is located only in the Southern Hemisphere. Air temperature +20 °С. It is divided into two types of climate. Humid tropical climate formed in the east and southeast of the Brazilian Highlands under the influence of trade winds that bring moisture. Precipitation is less than in the subequatorial zone. To the west, precipitation decreases and forms dry tropical climate. The cold Peruvian current has a great influence here. There is an inversion of temperatures: the air is saturated with moisture, but it is very cold, as a result of which precipitation does not fall. Here is the coastal Atacama Desert.
subtropical belt located south of 30º S. sh., within its limits three types of climate are formed. On the west coast subtropical mediterranean climate with dry, cool summers (+20°С) and humid warm winters (+10°С, cloudy rainy weather prevails). As we move deeper into the mainland, the climate becomes continental subtropical. Precipitation falls only 500 mm.
Formed on the east coast subtropical humid climate: summer temperature in January +25 °С, and winter temperature in July +10 °С, precipitation falls up to 2000 mm per year.
temperate climate zone located south of 40º S. Formed on the west coast maritime temperate type climate: warm humid winter (+5 °С), humid cool summer (+15 °С); precipitation - up to 2000 mm and more. In the eastern part of the belt - temperate continental type climate: winter is colder (0 °С), summer is warm (+20 °С). Precipitation - 300 mm.
formed in the Andes mountain type climate. Here, climatic zones replace each other according to the law of vertical zonality. At the foot of the mountains, the climate does not differ from the surrounding areas. As you rise, the temperature and precipitation change.
Land waters. South America is rich in inland waters. Most of the rivers are fed by rain, some get water from the melting of snow and ice in the mountains. The largest river of the Earth Amazon (6400 km) flows through the territory of the mainland. The area of its river basin is 7 million km2, which is almost 40% of the mainland. Being in a zone of high humidity, the river is full of water all year round. The river floods twice a year: in May during rains in the Southern Hemisphere and in October-November in the Northern Hemisphere.
Unlike the Amazon, the Orinoco (2730 km) and Parana (4380 km) rivers have a pronounced seasonality of flow. The flood period on the rivers falls on the summer wet season. Flowing down from the Andes rivers in the upper reaches form waterfalls. On one of the tributaries of the Orinoco is the highest waterfall in the world - Angel (1054 m); On one of the tributaries of the Parana is the Iguazu Falls.
Of the large lakes in South America, the most famous are: Lake Maracaibo, which is a desalinated lagoon near the Caribbean Sea.
Lake Titicaca is located in the Andes at an altitude of 3800 m - the largest alpine lake in the world.
natural areas. Wet equatorial forests, or selva, are located in the Amazon basin, on both sides of the equator and occupy almost half the area of the mainland. This is the largest forest area on Earth. High average annual temperatures and air humidity create conditions for the formation of impenetrable Amazonian forests. At least 40 thousand species of plants grow on fertile red-yellow ferralitic soils. Ficuses, heveas (rubber-bearing plants), various types of palms, creepers, "mahogany" (paubrazil), cinchona - this is not a complete list of representatives of the selva plant world. Many of them are the most valuable tree species, medicinal plants, as well as natural dyes. The impenetrability of the Amazonian forests led to the adaptation of animals to an arboreal lifestyle - sloths, chain-tailed monkeys, jaguars. Agouti is found here - an animal of a detachment of rodents, whose teeth are strong as a chisel, capable of cracking the tree peel of an American walnut. Also typical representatives of the selva are porcupines, armadillos, anteaters, numerous bird species (hummingbirds, toucans, parrots).
The Orinoc lowland and most of the Guiana and Brazilian highlands are occupied by savannah zone, which forms on red ferrallitic and red-brown soils. On the Orinok lowland they are called llanos (from Spanish - plains). Here, among the tall grasses, individual trees grow - palm trees, acacias. On the Brazilian plateau, the savannas are called campos(from Portuguese - plain). There is less woody vegetation here, mostly shrubs, cacti, and grasses. Of the animals, ungulates (deer, wild pigs-bakers), cougars, armadillos, jaguars are common.
South of the savannas is steppe zone, or pampas(on the La Plata lowland). Due to the rich cereal vegetation cover, fertile red-black soils are formed here. In this zone there are pampas deer, pampas cat, many rodents, birds.
Semi-desert and desert zone not widely used in South America. Desert soils, ephemera and cacti form in the Atacama Desert.
Hard-leaved evergreen forests and shrubs are common on the Pacific coast.
In the Andes, altitudinal zonality differs in the composition of natural zones and depends on the latitudinal position of the mountains. In the region of the equator, the altitudinal zonality is most fully expressed. At an altitude of 2800 m, mountain evergreen forests grow, which at an altitude of 3400 m are replaced by mountain alpine meadows - paramos. The amount of precipitation decreases to 250 mm, the air here is the driest in the world and rarefied, the rays of the sun are burning. Typical inhabitants of the highlands are the spectacled bear, chinchilla, llama, condor.
Australia and Oceania. Geographical position. By area (about 8 million km2) Australia occupies the last place among the continents; located in the Eastern and Southern Hemispheres. The length of the mainland from north to south is 3200 km, from west to east - 4100 km. Australia is washed by the waters of the Pacific and Indian Oceans, the coastline is slightly indented
AT Oceania includes islands and archipelagos located in the central and southwestern Pacific Ocean. This includes almost 7000 islands with a total area of about 1.3 million km2.
Relief and geological structure. In the past, Australia broke away from Gondwana. It is based on a platform (part of the Indo-Australian Plate) that experiences slow ups and downs. Australia is the flattest continent with a flat, uniform relief. In the west of the mainland, the relief is represented by low plateaus. On the East Australian Plateau, weathering processes have led to the formation of blowout remnants.
The central part of the mainland is occupied by a lowland - the Central Plain, covered with a thick sedimentary cover. Its height does not exceed 100 m. Strongly destroyed mountains stretch along the eastern coast - the Great Dividing Range with a maximum height of 2230 m (Kostsyushko). The Australian Alps, up to 2000 m high, are mountain ranges separated by basins; in some parts, cones of extinct volcanoes have been preserved. The western slopes of the Australian Alps gradually pass into the Central Plains.
Most of the islands in Oceania are of volcanic origin, the most famous among them being the Hawaiian Islands. These islands are seismic. The largest island of mainland origin is New Zealand. New Guinea is the second largest island in the world.
The relief of the islands is varied and is represented by mountain ranges and low plains. Biogenic (coral) islands form atolls.
Climate. The location of Australia in tropical latitudes (the Southern Tropic crosses the mainland almost in the middle) determines the dry and hot climate on the mainland. Mountains in the east of the mainland weaken the influence of the ocean on the mainland.
The north of the mainland is located within subequatorial climate zone, a monsoonal (variably humid) climate is formed here. In summer, equatorial air masses prevail here, due to which hot, humid weather is established. In winter, dry tropical air masses dominate here, with little precipitation.
Most of Australia lies in tropical climate zone, in which tropical dry and tropical humid types of climate are formed. Humid tropical climate distributed on the east coast, where the southeast trade winds dominate. They bring a lot of moisture from the Pacific Ocean and leave it on the eastern slopes of the Great Dividing Range - up to 1000-1500 mm per year. Dry tropical climate distributed in the central and western parts of the tropical belt. Precipitation falls 250-300 mm per year; temperature in summer +30 °С, in winter +15 °С.
AT subtropical climate zone There are three types of climate. Subtropical humid climate is formed in the east of Australia: January temperature +22 °С, July temperature +6 °С, precipitation throughout the year. The subtropical continental climate spreads along the Great Australian Bight and is characterized by low rainfall. The subtropical Mediterranean climate is formed in the southwest and is characterized by hot summers and wet, rainy winters. The annual rainfall reaches 500-600 mm per year.
Tasmania is located in temperate climate zone. Western winds bring a lot of precipitation; winters are relatively warm, summers are cool.
All the islands of Oceania, except for New Zealand, lie in the equatorial and tropical climatic zones. The climate is mild, warm, without large temperature fluctuations. Winds from the ocean soften the heat, but destructive hurricanes are quite common.
Land waters. There are no full-flowing large rivers in Australia. This is due to the aridity of the climate, as well as the absence of glaciers and snowfields in the mountains. The largest river system Murray with a tributary Darling belongs to the Indian Ocean basin. For the inland desert regions of the mainland, temporary streams are characteristic - screams. Most lakes in Australia are endorheic, filled with rainwater during dry periods. The largest Lake Eyre in the dry season dries up almost completely, turning into a salt marsh.
natural areas. The isolated position of Australia and the islands of Oceania has led to the fact that their flora and fauna are very different from other continents. Endemic vegetation is 75%. The only two species of egg-laying mammals in the world, the platypus and the echidna, have been preserved here. Australia is a habitat for marsupials - kangaroos, opossums, marsupial badgers, koala bears, wombats (marsupial rodents), the Tasmanian devil. Birds of paradise, cassowaries, black swans are found here.
The northeast of the mainland is located in zone of humid and variable-moist tropical forests. Red ferralite soils are formed here and palm trees, ficuses, and ferns grow. Woodland and savannah zone represented by dry eucalyptus forests growing on red-brown soils. Kangaroos and emus live here. The interior of Australia is desert and semi-desert zone with thickets of evergreen thorny shrubs - scrubs. Among animals, dingoes, emus, wombats (marsupial rodents), giant kangaroos are common. Moist subtropical forests represented by beech and eucalyptus trees. In the Australian Alps, altitudinal zonality is expressed: forests grow at the foot of the mountains, giving way to alpine meadows. tasmania island located in the temperate forest zone.
Almost all the islands of Oceania are covered evergreen wet forests with a variety of plant species: coconut palm, rubber trees, mangoes, breadfruit and melon trees, bananas. In New Zealand, on the South Island, common temperate forests. The fauna of Oceania is peculiar: among the few mammals there are no predators, among the reptiles there are no poisonous snakes, there are many sea birds.
Antarctica. Geographical position. Antarctica is an icy continent that is part of the southern polar region of the Earth - Antarctica. Antarctica is limited by the Antarctic Circle, it also includes the southern margins of the Pacific, Atlantic and Indian oceans and islands located within 50-60 ° S. sh. The area of Antarctica is 14 million km2. The coastline of the mainland is formed by high steep glaciers and is washed by the seas: Ross, Amundsen, Bellingshausen, Weddell. The Antarctic Peninsula juts deep into the waters of the Atlantic Ocean.
Relief and geological structure. The average height of Antarctica, together with the ice sheet, is 2040 m. The under-ice part of it lies below the ocean level. The Transantarctic Mountains divide the mainland into western and eastern parts. Scientists have established that the Antarctic platform lies at the heart of the eastern part. It is associated with a high plateau covered with ice. The western part consists of a mountainous relief - a folded region of Alpine age (altitude about 5000 m). Until now, volcanic activity has not stopped here, on one of the islands of the Ross Sea there is an active volcano Erebus. In the west of the continent is the highest point - the Ellsworth Mountains (up to 5140 m above sea level).
In the coastal zone, there are so-called oases - this is land free of ice.
Deposits of non-ferrous metal ores, coal, and iron ore have been discovered in Antarctica.
Climate and inland waters. The climate of the mainland is very severe, formed under the influence of geographical location and ice cover. With the exception of the northern part of the Antarctic Peninsula, the mainland is located in the Antarctic climatic zone.
Cold and dry air masses form over the mainland. In the winter months, frosts reach -80 °С, in summer - about -20 °С. The lowest temperature on Earth was recorded at Vostok station: -89.2 °C. Precipitation falls only in the form of snow. Their number naturally decreases from the coasts to the center of the mainland, where their number is 50 mm per year. The average rainfall is 200 mm. The climate of the center of the mainland differs from the coasts, from the center, where the continental cold air moves towards the coastal zone, forming katabatic winds. On the coast, the wind speed reaches 90 m/s and the amount of precipitation increases to 300 mm per year. From the center of the mainland to the coasts, ice is constantly moving, where ice shelves are formed. In summer, the ice around the coast melts and breaks off from the glacier in huge massifs - icebergs.
The internal waters of Antarctica are mostly in a solid state - in the form of snow and ice. The ice mass is 24 million km3. This is more than 90% of all fresh water reserves that are stored here in a frozen state.
natural areas. Most of Antarctica is occupied by the icy Antarctic desert. The organic world is represented by mosses, lichens. Representatives of the animal world are associated with the ocean: Adélie penguins, emperor penguins, seals, whales. In summer, gulls, albatrosses, petrels, and cormorants nest on the banks.
The mainland is conditionally divided into two natural areas (Fig. 35)??. Western Antarctica is represented by subglacial mountainous and glacial relief. East Antarctica occupies the largest part of the mainland, where the lowest temperature on Earth is recorded.
North America. Geographical position. North America, the third largest continent, with an area of 20.36 million km2, is located entirely in the Northern Hemisphere. The northern part of the mainland is located far beyond the Arctic Circle, the tropic passes in the south. North America is separated from South America by the Panama Canal, and from Eurasia by the Bering Strait.
The coast of North America is washed by the Pacific Ocean - in the west, the Arctic Ocean - in the north, the Atlantic Ocean - in the east. The coastline is strongly dissected in the northwest, north and northeast. The elements of the coastline are: bays - Hudson, Mexican, California; peninsulas - Florida, California, Alaska, Labrador; large islands - Greenland, Newfoundland, Canadian Arctic Archipelago, Greater and Lesser Antilles, Aleutian Islands.
Relief and geological structure. The relief of the mainland is diverse and relatively compact with mountains in the west and southeast and plains in the north and center. Most of the mainland plains formed on the ancient N American Platform; a vast flat area in the north formed within the Canadian Shield. The northern parts of the plains have pronounced traces of glaciation - hills, ridges. The chain of the Great American Lakes is, as it were, the boundary of the glacier. To the south are the Central Plains 200-500 m high, formed by continental and marine sediments. To the west of them are the Great Plains, which are a system of plateaus 500-1700 m high, with a flat surface divided by ledges. They are composed of sedimentary rocks of continental and marine origin. To the south of the Central Plains is the Mississippi Lowland, up to 100 m high. It is a flat plain formed by river sediments, bordering the coast of the Gulf of Mexico. The Mississippi Lowland is crossed by numerous rivers flowing from the Central and Great Plains, the Appalachians and the Cordilleras.
The Appalachians, located in the east of the mainland, are low folded-block mountains (up to 200 m) with wide valleys, plateaus and plateaus. The highest point is Mount Mitchell (2037 m). A distinctive feature of the mountains is the inversion relief, i.e., the external structure does not correspond to the tectonic structures underlying the landforms.
The main mountain system of North America - the Cordillera stretches along the western edge of the mainland. The highest point is Mount McKinley (6193 m). This folded belt arose at the junction of two lithospheric plates - oceanic and continental. Active processes of mountain building are still going on here: frequent earthquakes and volcanic activity. The largest volcanoes are Orisabo, Katmai. In the Cordillera, two chains of mountain ranges stand out: the Cordillera proper and the Rocky Mountains. Actually the Cordilleras are huge arcs that border the oceanic depression; ridges and plateaus here are crossed by tectonic faults. In the Rocky Mountains, post-volcanic phenomena are observed in the Yellowstone National Park area - geyser eruptions, thermal springs, mud volcanoes. Between the chains of mountain ranges, a system of plateaus and uplands is formed: the Yukon Plateau (within Alaska), the Fraser Volcanic Plateau (in Canada), the Columbian Plateau, the Great Basin, and the Colorado Plateau.
Climate. The diversity of the climate of the mainland depends on its position in different latitudes. North America is located in all climatic zones, except for the equatorial one. Another important climate-forming factor is the relief of the mainland. Meridional large mountain systems contribute to the penetration of cold arctic air far to the south and tropical air masses to the north. In the inner parts of the mainland, a continental climate is formed. The climate is also influenced by ocean currents: cold - Labrador and California - lower the temperature in the summer, and warm - the Gulf Stream and the North Pacific - increase the temperature in winter and increase the amount of precipitation. However, high mountains in the west make it difficult for air masses to penetrate from the Pacific Ocean.
Within arctic climate zone are the northern margin of the mainland and most of the islands of the Arctic Ocean. In winter, the temperatures here are very low, snow storms are frequent, and cover glaciation is developed. Summer is cold, short, the air warms up to +5 °С. The average annual rainfall is less than 200 mm.
Subarctic climate zone covers the territory between the Arctic Circle and 60 ° N. sh. In the west, the belt extends below the latitude of Moscow. This is due to the influence of the Arctic Ocean, the cold Labrador Current and the northeast winds from Greenland. There are oceanic and continental types of climate. In winter, the temperature reaches -30 °C, near the coast of the oceans the temperature ranges from -16 to -20 °C. Summer temperatures are 5-10 °С. The amount of precipitation varies from 500 mm per year in the east to 200 mm per year in the west (Alaska region).
Most of the mainland is located within temperate climate zone. It distinguishes three climatic regions:
– area temperate maritime climate in the west of the mainland (the Pacific coast and the western slopes of the Cordillera). Westerly transport dominates here: winds bring a large amount of precipitation from the ocean - up to 3000 mm per year. The average temperature in January is up to +4 °С, the average temperature in July is up to +16 °С;
– area located in the central part of the belt. It is characterized by relatively warm summers - from +18° to +24°С; cold winter - up to -20 ° С. The amount of precipitation in the west is up to 400 mm, but their amount increases to 700 mm in the east. The practically open space of this part of the mainland is subject to the invasion of air masses from both the north and the south. Therefore, atmospheric fronts are frequent here, accompanied by snow storms in winter and showers in summer;
– area temperate continental climate distributed along the east coast of the Atlantic Ocean. In winter, cyclones are frequent here, bringing a lot of snow; temperature from -22 °С in the north to -2 °С in the south. Summer is not hot - up to +20 °С; the cold Labrador current has its influence. The amount of precipitation is different, depending on the relief and distance from the ocean, but on average - 1000-1500 mm per year.
Subtropical climate zone located on the territory from 40 ° N. sh. to the coast of the Gulf of Mexico. The territory also has a large extent from west to east, so there are differences in climate types and the following climatic regions are distinguished:
- in the West subtropical mediterranean climate with warm and humid winter: temperature +8 °C, rainfall up to 500 mm per year; and dry, cool summers: temperature +20 °С - the cold California current has its effect;
– area subtropical continental climate located in the center of the climate zone. Characterized by high temperatures in summer and low rainfall throughout the year;
– area humid subtropical climate covers the Mississippi lowlands. Summer temperatures up to +30 °С, mild winters up to +5 °С.
South of 30° N. sh. situated tropical climate zone, it is hot all year round. On the east coast of the mainland and on the islands, there is a large amount of precipitation brought by the trade winds. The California Peninsula has a dry tropical climate.
located on the narrowest southern part of the mainland. Here, typical for this climatic zone, high temperatures during the year are about +25 °С. Winds from the Pacific and Atlantic oceans bring a lot of moisture - up to 2000 mm per year.
Land waters. North America has large full-flowing rivers, numerous lakes and significant groundwater reserves. In terms of annual runoff, the mainland is second only to South America. The river network is unevenly distributed over the mainland, and the rivers have different types of food.
The main river system of the Mississippi mainland with a tributary of the Missouri has a length of 6420 km, and carries its waters to the Gulf of Mexico. The river basin includes the Rocky Mountains, the Appalachians, the Central and Great Plains. The river is full-flowing all year round and has snow and rain types of food. The rivers of the Pacific basin have a large steepness of fall, so they are turbulent, rich in hydropower. Among them are the large Colorado (2740 km) and Columbia (2250 km) rivers. The Yukon River in northwestern Alaska is full of water in the summer, during the snowmelt period. The largest river in the Arctic Ocean basin, Mackenzie, with a length of 4250 km, originates in the Great Slave Lake.
Most of the lakes in North America are located in areas that have undergone glaciation. The most unique system of the Great Lakes - Superior, Huron, Michigan, Erie, Ontario - the world's largest accumulation of fresh water on land. Most of the lakes are of considerable depth, for example, Lake Superior is almost 400 m deep. Lakes Erie and Ontario are connected by the Niagara River. Cutting through a hilly ridge, the river overthrows the Niagara Falls, 50 m high and 1 km wide.
Large lakes of North America are also Winnipeg, Great Slave, Great Bear, Athabasca. Residual lakes have been preserved in the basin of the Great Basin - the Great Salt, Utah.
natural areas. Arctic desert zone occupies most of Greenland and the islands of the Canadian Arctic Archipelago. The long polar winter, temperatures below -40 ° C, strong winds make living conditions harsh. Modern glaciation is developed here - this is an almost lifeless territory. On the ledges of bedrocks, one can observe sparse vegetation - mosses, scale lichens. Among animals, polar bears, wolves, foxes, musk musk oxen are common.
Tundra and forest tundra zone occupies the southern parts of the islands and the north of the mainland, including half of the island of Labrador. The tundra is significantly waterlogged. Sedges, saxifrage, dandelions, polar poppies grow on marsh and tundra-gley soils. The species composition of the animal world is not rich - arctic foxes, lemmings, reindeer. The forest tundra stretches from the Labrador Peninsula to the Mackenzie Mountains. Woody vegetation appears here - black and white spruce, balsam fir, birch, aspen. The fauna is represented by brown bears, arctic foxes, red foxes, there are also muskrats, martens, minks, beavers.
Taiga zone located in the north of the temperate climate zone. The American taiga is similar to the Eurasian taiga, but richer in species composition. The above tundra species are joined by larches and pines. The so-called Pacific taiga is included in the oceanic coniferous forests. Hemlock, thuja, and the mighty Sitka spruce predominate here. From animals here there is a grizzly bear, a Sitka deer, a skunk, a Pacific raccoon.
Mixed forest zone in the Great Lakes region it is represented by lindens, oaks, elms, numerous types of maples, ash trees, and thujas.
broadleaf forest in the Appalachian region, it grows on brown forest soils. The plant composition includes beech, plane tree, chestnut, linden. Among the animals there are Virginia opossum, porcupine, bison.
To the west, broad-leaved forests border tall grasslands, or prairie, on chernozem soils. They are currently open.
In the subtropical zone, the change of natural zones occurs from east to west, their formation is associated with differences in moisture. Grow in the East wet evergreen mixed forests, to the west are the prairies, in the interior of the Cordillera - semi-desert and desert zone.
Within the tropical and subequatorial belts, savannas on the high plateaus of Central America, and on the coast of the Gulf of Mexico - tropical rainforests.
Eurasia. Geographical position. Eurasia is the largest continent on Earth, occupying 1/3 of all land. Its area is 54 million km2. The length of the mainland from north to south is 8,000 km, from west to east - 10,000 km.
Eurasia is located in the Northern Hemisphere and is washed by all four oceans. The coastline is heavily indented and forms a large number of peninsulas, bays, straits.
From the north, Eurasia is washed by the seas of the Arctic Ocean: Barents, Kara, Laptev, East Siberian, Chukchi. The largest islands are Novaya Zemlya, Svalbard; peninsulas - Taimyr, Yamal; Bering Strait. The western shores are washed by the Pacific Ocean, which forms marginal seas off the coast of Eurasia: the Bering, Okhotsk, Japanese, Yellow, East China, South China. The largest islands: Sakhalin, Hokkaido, Honshu, Philippine, Big Sunda, peninsulas: Kamchatka, Korea, Indochina. The seas of the Indian Ocean go deep into the land: the Red, Arabian and Persian and Bengal bays; large peninsulas - Arabian, Hindustan, Malacca. From the west, the mainland is washed by the seas of the Atlantic Ocean - the Baltic, Black, Azov, Mediterranean, Northern, Norwegian, as well as the straits: Gibraltar and the English Channel and the Bay of Biscay. There are large islands here: Great Britain, Iceland, Ireland, as well as peninsulas: Scandinavian, Iberian, Apennine. Eurasia is separated from Africa by the Suez Canal, and from North America by the Bering Strait.
Relief and geological structure. The geological structure and, consequently, the relief of Eurasia are extremely complex and varied. The continent consists of several ancient platforms: the East European, Siberian, Sino-Korean, Indian, African-Arabian, as well as the younger West Siberian plate and its continuation in the south of the Turanian plate. They correspond to the plains: East European, West Siberian, Great Chinese, or vast plateaus: Deccan, Central Siberian, Arabian.
The Alpine-Himalayan fold belt stretches along the southern margin of Eurasia. It corresponds to mountains of different heights: the Pyrenees, the Apennines, the Alps, the Carpathians, the Caucasus, the Pamirs. The Himalayas is the highest mountain system in the world, within its boundaries is the highest point on the Earth - Mount Chomolungma (Everest) with a height of 8848 m. 7000 m
In the east of Eurasia, the Pacific belt of folded mountains (part of the Pacific "Ring of Fire") stretches from Kamchatka to the Malay Archipelago. The ridges are located along the coast of the Pacific Ocean (mountains of Kamchatka and Sakhalin). Parallel to them, underwater ridges also run along the bottom of the ocean. Speaking above the surface of the ocean, they form the islands (Kuril, Japanese, Philippine, Sunda, Mariana). There are deep-sea trenches in the Pacific Ocean (Mariansky, 11,022 m).
Active tectonic movements take place in folded belts. This is manifested in active seismicity and volcanism (in the area of the Japanese and Philippine islands, on the Iranian and Armenian highlands, on the coast of the Aegean and Adriatic seas). The highest active volcano in Eurasia is Klyuchevskaya Sopka (4750 m) on the Kamchatka Peninsula. The most famous volcanoes: Vesuvius (Apennine Peninsula), Etna (Sicily Island), Hekla (Iceland Island), Fujiyama (Honshu Island), Krakatoa (in the Malay Archipelago).
The regions of ancient folding include the Urals, Altai, Tien Shan, Sayans, and the low mountains of Europe. They appeared in the Paleozoic, Mesozoic time, gradually collapsed, but then underwent uplift along the faults. As a result, revived mountain systems appeared - Tien Shan, Kunlun, Altai. Currently, the Ural Mountains are heavily destroyed and flattened.
In the foothill troughs and intermountain depressions, lowlands were formed - the Indo-Gangetic, Mesopotamian, Middle Danube, and Padan.
Climate. The length of the mainland from the Arctic to the equator determined the diversity and contrast of its climate. Here is the cold pole of the Northern Hemisphere in Oymyakon, where a temperature of -70 °C was recorded; in one of the driest regions in the world in Arabia, only 44 mm of precipitation falls annually, and in North-East India (Cherrapunji), the amount of precipitation is 12,000 mm or more per year.
High mountain systems in the south and east contribute to the penetration of air masses from the Atlantic and the Arctic Ocean into the interior of the mainland, while the influence of the Pacific and Indian Oceans extends only to the southern and eastern outskirts of the continent.
In Eurasia, the western transport of air masses dominates in temperate latitudes. This is the only continent located in all climatic zones.
AT arctic and subarctic climatic zones two types of climate are distinguished: in the western regions - a marine type of climate with a large amount of precipitation and small amplitudes of temperature fluctuations due to mild winters and cool summers; in the eastern regions climate continental with less precipitation and very cold (up to -45 °С) winter.
temperate climate zone occupies most of Eurasia, so the climatic conditions here are very diverse. Within its limits, four types of climate are distinguished:
1. The marine type of climate is formed on the west coast under the influence of the air masses of the Atlantic Ocean. It is characterized by mild winters and cool summers; the amount of precipitation during the year is up to 1000 mm.
2. Moderately continental type of climate - in the territory of Central and Eastern Europe to the Urals. With distance from the ocean, the difference between summer and winter temperatures increases. There is more precipitation in summer than in winter.
3. A sharply continental type of climate - in Siberia and Central Asia. It has very cold and dry winters and moderately humid summers (up to 200 mm of precipitation).
4. Monsoon temperate type of climate is typical for the Far East. Winters are always cold and dry, while summers are warm and humid.
AT subtropical zone There are three types of climate:
1. Mediterranean type of climate in the west of the mainland with dry summers and wet winters.
2. Subtropical continental type of climate in the areas of the Near Asian highlands with relatively cold winters and hot dry summers.
3. Monsoon type of climate in the east of the climatic zone: warm winter, seasonal precipitation, up to 1000 mm per year.
tropical belt includes the Arabian Peninsula, Mesopotamia, the south of the Iranian Highlands, the lower reaches of the Indus. Dry continental tropical air dominates here; temperature in summer 30-36 °С, in winter - up to -23 °С; precipitation - less than 100 mm.
Subequatorial climate zone formed on the peninsulas of Hindustan, Indochina. It is characterized by alternating dry and wet seasons. In summer, a large amount of precipitation falls (up to 12,000 mm in Cherrapunji).
Equatorial climate zone distributed throughout the Malay Peninsula and the islands of the Malay Archipelago. It is characterized by high temperatures, excessive moisture throughout the year.
Land waters. Eurasia is quite rich in inland waters. Their distribution across the mainland depends on climatic conditions. The rivers of the mainland belong to the basins of all four oceans. There are territories belonging to the basins of internal flow. There are all types of rivers in terms of food sources and flow regime.
The basin of the North Atlantic Ocean includes: the Ob, the Yenisei, the Pechora, the Lena, the Vilyuy, and others. These rivers have a well-defined spring flood that occurs when the snow melts; floods can occur in summer and autumn due to heavy rains. The Atlantic Ocean basin includes: the Danube (2850 km) - the largest river in Europe, originates in the Alps, other large rivers: the Rhine, Elbe, Odra, Vistula, Tahoe, Duero.
The Indian Ocean basin includes the Tigris, Euphrates, Indus (3180 km), Ganges (2700 km), Brahmaputra, originating in the Himalayas. In summer, the water level in the rivers rises due to heavy rains and snowmelt in the mountains.
The large Chinese rivers Yangtze (5800 km) and Yellow River (4845 km), carrying their waters to the Pacific Ocean, overflow in summer during the wet monsoon.
The lakes of Eurasia have a different origin. The largest are the Caspian and Aral Seas. The deepest lake on Earth - Baikal - was formed in a tectonic depression, its depth is 1620 m. One of the most saline lakes in the world - the Dead Sea (270‰) - is located 402 m below sea level.
natural areas, like no other continent, they are well expressed and varied.
Arctic deserts, tundra and forest tundra occupy the northern islands and a narrow strip of the northern coast of the mainland. In the west, the southern border at 69 ° N. sh. to the east it shifts to 60°N. sh.
The temperate forest zone includes coniferous, mixed and broad-leaved forests and occupies most of Europe and Siberia.
Taiga represented by fir, cedar. Among the animals there are martens, chipmunks, hares, elks, brown bears, insectivores (woodpeckers, finches), birds of prey, as well as capercaillie, partridges, black grouse.
For broadleaf forest zones from beech and oak, a humid warm climate and brown forest soils are favorable. However, the forests have been severely cut down and in their place are industrial areas. The forest-steppe is replaced by the steppe, which is located north of the Black Sea. Cereals dominate here, under which fertile chernozem soils have formed.
desert landscapes located in the center of Eurasia: winters are cold and frosty. There is no succulent vegetation capable of storing water, and saltwort, wormwood, and saxaul prevail. In Arabia and Mesopotamia, the deserts are similar to African ones.
Grows in the Mediterranean evergreen hardwood forests and bushes. Summers are dry and hot, while winters are warm and humid. Various palm trees, grapes, olives and citrus fruits feel good here.
In the east, in the subtropical zone, a different picture is observed: precipitation falls in summer, winters are cool and dry. Magnolias, camellias, bamboo, oak, beech, hornbeam grow here. Few wild animals survived. Among them are the Himalayan bear, leopards, monkeys.
Variable wet (monsoon) forests distributed in areas with a well-defined dry period.
South Asia is located in the subequatorial and equatorial belts and is under the influence of the southwest monsoons. Territories are occupied humid equatorial forests.
In the Himalayas, altitudinal zonality is pronounced. Here you can find almost all the natural zones of the Earth, which replace each other when climbing the mountains. It is not for nothing that plant hunters tend to the Himalayas, because here you can collect an extraordinary collection, especially since the places are difficult to access and little mastered by man.
Pacific Ocean. Geographical position. The Pacific Ocean is the largest and oldest of all oceans. Its area is approximately 179 million km2 (1/3 of the planet's surface). Located in the Northern and Southern Hemispheres between Eurasia and Australia in the west, North and South America in the east and Antarctica in the south. More than 20 seas and a huge number of islands (more than 10,000) belong to the Pacific Ocean. In the Pacific Ocean there is a unique natural formation - the Great Barrier Reef, stretching for 2200 km along the eastern coast of Australia.
Bottom relief. The Pacific Ocean is the deepest. Its average depth is 3980 m, the maximum reaches 11022 m in the Mariana Trench. The bottom of the Pacific Ocean is characterized by tectonic activity and a complex structure. The ocean shelf is slightly developed (the coasts of North and South America and Antarctica). The widest shelf off the coast of Asia and Australia. The continental slope of the Pacific Ocean is quite dissected by numerous canyons. The bed of the ocean is heterogeneous, it is characterized by uplifts, basins, trenches. Here, a chain of meridianally located uplifts of the bottom is well expressed, which form a mid-ocean ridge, which is somewhat shifted to the east. The height of the ridge reaches 2 km, and the width is 2 thousand km. In addition, individual flat-topped mountains are common at the bottom. As scientists suggest, in the past these were islands, which then sank to a depth of 2 km. In places where the Pacific Plate interacts with other lithospheric plates, seismic zones are formed - the Pacific Ring of Fire. There are many islands of volcanic origin in the ocean, such as the Hawaiian Islands. In contrast, there are islands formed by coral deposits.
Minerals. Significant areas of distribution of ferromanganese nodules are located in the Pacific Ocean. These are polymetallic ores, which include many metals: manganese, iron, copper, cobalt, nickel, aluminum, etc. These areas are confined to the Pacific ore belt. Gold sands are known off the western coast of North America (Alaska, California). Of the non-metallic raw materials located in the shelf zone, offshore deposits of oil, gas and coal are of great importance. Mining is carried out by the USA, Japan, Indonesia, Peru, Chile, Brunei. Of the building materials, there is sand, pebbles, gravel, limestone-shell rock.
Climate. The vast expanses of the ocean lie in all climatic zones, except for the polar ones, which determines the diversity of its climate. In subpolar and temperate latitudes, westerly winds dominate; in the tropics, trade winds that are stable in direction and speed develop. In the tropics, typhoons often form, the size of which reaches up to 1800 km. Typhoons are especially frequent in the Northern Hemisphere in July-October, in areas from 10° to 30° N. sh. Off the coast of Eurasia in the western part of the ocean, monsoons dominate.
The air temperature over the Pacific Ocean varies from the equator to the subpolar regions - from 27 °С to –39 °С, respectively. The highest temperatures (up to +36°C) are observed in the area of the Northern Tropic in the Philippine Sea, and the lowest temperatures are observed in Antarctica (up to –60°C).
Currents and properties of waters. Currents on the surface of the ocean are characterized mainly by the circular rotation of the waters. In the north, the circulation moves clockwise and is composed of the Northern Equatorial, Kuroshio, North Pacific and California currents. In the south, the circulation moves counterclockwise and is composed of the South Trade Winds, East Australian, Peruvian and West Wind currents.
The Pacific Ocean is the warmest on Earth. The average surface water temperature is 19°C. This is due to the large amount of solar heat entering its surface. Yet the temperature of surface waters is changing. Near the equator it is 29 °C, and in the Sea of Okhotsk and the Bering Sea it is up to 1 °C.
The average salinity of the ocean is 34.5‰; in the tropics, it reaches 36‰, and at the equator, salinity is less, because more precipitation falls here (up to 3000 mm).
The biggest disaster for the islands and the Asian coast, as well as the South American Pacific coast, are frequent tsunamis, bringing heavy destruction and loss of life.
organic world. In terms of species composition, the fauna of the ocean is 3-4 times richer than in other oceans. A wide variety of representatives of the organic world are distributed here, starting from the world's largest fish - the whale shark, to flying fish, squid, sea lions. Half of the world's fish catch comes from the Pacific Ocean. A significant part of the catch is shellfish, crabs, shrimps, krill. The warm shallow waters are home to thousands of exotic fish and algae. The warm waters of the ocean promote the work of corals.
Indian Ocean. Geographical position. The Indian Ocean is the third largest on Earth. Its area is 76 million km2. It extends from the coast of East Africa to Indonesia and Australia, and from the coast of India to Antarctica. Most of it is located in the Southern Hemisphere. The coastline of the ocean is slightly indented. Large islands in the ocean are: Sri Lanka, Madagascar, Kalimantan, etc. It includes 6 seas, among them: the Red and Arabian Seas, also bays: Bengal, Persian, Great Australian.
Relief. The average depth of the ocean is about 3700 m, and the maximum reaches 7729 m in the Yavan Trench. At the bottom of the Indian Ocean are huge sections of the earth's crust - the African, Indo-Australian and Antarctic plates. In the western part of the ocean, a system of mid-ocean ridges extends. They are associated with deep faults, areas of earthquakes and volcanism. Numerous basins are located between the ridges. The ocean shelf is poorly developed, only in the Persian Gulf it increases.
Minerals. In the shelf zone, tin ores, phosphorites, and gold have been found in rock deposits. The Persian Gulf and adjacent shelves contain the world's largest oil and gas fields. At the bottom of the basins of the Indian Ocean, ferromanganese nodules were found in large quantities.
Climate. The Indian Ocean is located in the equatorial, subequatorial and tropical climatic zones. The northern part is influenced by land. This is where the seasonal winds come from. monsoons. In summer, monsoons carry a huge amount of moisture to land (up to 3000 mm) in the Bay of Bengal area. To the south - from 10 ° to 30 ° S. sh. an area of high pressure is formed, where the southeast trade wind dominates, in temperate latitudes - strong stable westerly winds. The south of the Indian Ocean is experiencing a significant cooling effect of Antarctica - these are the most severe areas of the ocean.
Currents and properties of ocean waters. Currents in the northern part depend on the monsoon winds, and their direction changes depending on the direction of the summer and winter monsoons. The monsoon, Somali and Trade wind currents form a strong circulation in the equatorial latitudes of the Indian Ocean. In the southern part of the ocean, the currents enter into a single ring-shaped movement of the waters of the World Ocean.
The Indian Ocean has a higher salinity than other oceans. There is a pronounced zonality in the distribution of salinity here: the highest salinity, up to 42‰, is in the Red Sea and the Persian Gulf, the average salinity is 35‰, and in the Antarctic waters it drops to 33‰.
The Indian Ocean is also characterized by zonality in the distribution of surface water temperatures. Between the equator and 10° N. sh. it is 30 °C, and to the north and south it drops to 24 °C. The closer the temperature is to Antarctica, the water drops from 15 °C to -1 °C.
organic world. The waters of the Indian Ocean serve as a habitat for various representatives of the animal world - sharks, whales, jellyfish, sea turtles, seals, sea elephants. The species composition of fish is rich - sardinella, anchovy, mackerel, etc. The tropical region of the ocean is one of the areas of wide distribution of coral polyps and the development of reef structures. A characteristic component of the landscape of the tropical coasts of the ocean are mangroves, where many oysters, shrimps, and crabs are found. Since ancient times, pearls have been mined in the ocean.
Atlantic Ocean. Geographical position. The Atlantic Ocean is the second largest on Earth. Its area is about 90 million km2; it extends from the shores of America in the west to Europe and Africa in the east. From north to south, the ocean stretches for 16 thousand km. Branches of the Atlantic Ocean form the North, Baltic, Mediterranean and Caribbean seas. The coastline in the Northern Hemisphere is strongly dissected by peninsulas - Labrador, Scandinavian, Iberian and bays - Mexican, Biscay, Guinea. There are large mainland islands in the ocean - Ireland, Newfoundland, Great Britain.
Relief. The average depth of the ocean is 3600 m, the maximum reaches 9207 m - the Puerto Rico Trench. The bottom of the ocean has a complex relief. The ocean shelf is quite developed, especially in the Western Atlantic near Labrador, Newfoundland, Florida, as well as in the North and Irish Seas. The ocean floor is characterized by a combination of deep-sea trenches, basins and seamounts. In the middle of the ocean floor there is a mid-ocean ridge, dissected by rift valleys. On both sides of the ridge lie relatively leveled basins separated by uplifts. Molten magma flows deep from under the crust to the ocean floor, solidifying, forming underwater ridges. Rising above the surface of the water, they form volcanic islands, such as the island of Iceland.
Minerals. The Atlantic shelves are rich in mineral deposits. Oil is being produced in the North and Caribbean Seas, the Gulf of Mexico. Tin deposits have been discovered off the coast of Florida and Great Britain, diamond deposits off Southeast Africa; ferromanganese nodules - at about. Newfoundland.
Climate. The considerable length of the ocean in the meridional direction determines the diversity of its climate. In the North Atlantic, especially in winter, strong westerly winds dominate. The tropical part of the ocean is under the influence of the trade winds, blowing steadily from east to west. Heat prevails in the equatorial Atlantic, and there is abundant rainfall throughout the year. Western winds prevail in the South Atlantic. The temperature regime of the air over the Atlantic Ocean is very diverse. In equatorial and tropical latitudes, it is 24 °С all year round; in temperate and polar latitudes, seasonality is observed - in winter from -20 °С to 24 °С, in summer from 18 °С to 30 °С.
Currents and properties of waters. Currents in the Atlantic Ocean mostly move in the meridional direction. An annular movement of surface waters is also formed here. In the Northern Hemisphere, it is formed by currents - Canary, North Atlantic, Gulf Stream, North Passat. In the Southern Hemisphere - the currents of the West Winds, Benguela, South Trade Winds, Brazil.
The average temperature of the surface waters of the ocean is 16 ° C, but it varies with latitude. In the equatorial latitudes, the temperature is 26 °C. In tropical and temperate latitudes, it depends on the season. The subpolar regions of the Atlantic have the lowest surface water temperatures.
The average salinity of the Atlantic Ocean is 35‰, and lower salinity is observed in the equatorial zone. This is due to the desalination effect of river runoff and the abundance of precipitation. In the tropical zone, the maximum salinity is 37‰.
organic world. The Atlantic Ocean is rich in flora and fauna. At a shallow depth in the ocean, there are many green plants - sea lettuce (up to 1 m long), sea moss, brown algae, kelp, etc.
In the southern tropical part of the Atlantic, an abundance of plankton, flying fish, and sharks. In the waters of the cold Canary Current, a large number of mackerel, halibut, flounder, herring, and mullet are found. The area of the Canary Islands is rich in lobsters, anchovies. In the waters of the North Atlantic, sea urchins, mollusks, holothurians, crabs, and salmon are common.
Arctic Ocean. Geographical position. The Arctic Ocean forms a body of water around the North Pole and is bounded by the coasts of Eurasia and North America.
The area of the ocean is about 15 million km2. In terms of indented coastline, it is second only to the Pacific Ocean. Here are the largest islands of the Earth - Greenland, archipelagos: Svalbard, Franz Josef Land, Novaya Zemlya, Canadian Arctic. The Arctic Ocean includes 11 seas.
Relief. The average depth of the ocean is 1220 km, the maximum is 5527 m in the northern part of the Greenland Sea. The ocean floor is an intercontinental trench. An essential feature of the ocean relief is the significant development of the shelf. The shelf is widest along the coasts of Eurasia and is 1300–1500 km. The central part - the bed of the ocean - is crossed by mountain ranges and deep faults (the Gakkel and Lomonosov ridges), between which lies the depression (Canadian) with a depth of 3879 m.
The shelf of the Arctic Ocean is a huge oil and gas basin.
Climate. The main features of the climate of the Arctic Ocean are determined by its position at high latitudes and the influence of a permanent ice cover. The climate of the ocean is arctic: the average summer air temperature is -2 °С, the winter temperature is -36 °С.
In the coastal regions of the seas washing Asia, an arctic continental climate is formed. It is characterized by relatively warm summers - 10 °C and cold winters -30 °C.
The maritime arctic climate is formed in the Barents Sea, in the western part of the Kara Sea and in the southern part of the Chukchi Sea. It is distinguished by relatively mild temperatures: in summer 6-8 °С, in winter not lower than -25 °С.
An anticyclone sets up over the central part of the Arctic Ocean in winter. In the subpolar regions bordering the north of the Atlantic and the northern part of the Pacific Ocean, due to the pressure difference, unstable winds with a speed of 5 m/s are formed. Storm winds with a speed of 15 m/s are most frequent in the Atlantic part of the ocean. Some coastal areas are characterized by local wind - boron– at speeds up to 40 m/s. Bora is observed on Novaya Zemlya, Franz Josef Land from October to May.
In summer, the pressure over the central part of the Arctic Ocean is lowered, winds with a speed of 3-4 m/s prevail. Storm winds are observed relatively rarely, mainly in the Norwegian and Barents Seas.
Currents and properties of waters. Currents on the surface of the Arctic Ocean are formed under the influence of prevailing winds, water exchange with the Atlantic and Pacific oceans and the inflow of river waters.
In the Pacific part, a clockwise circulation is expressed with a center over the Canadian Basin. The flow velocity is 2-3 m/s. On the northern margin of the Chukchi Sea, a transarctic current arises in the direction from east to west at a speed of 2 to 5 m/s. Passing into the East Greenland current, it enters the North European part of the ocean. Atlantic waters enter the Arctic Ocean in the form of the Norwegian current at a speed of 40-50 m/s.
The temperature and salinity of surface waters are affected by the high latitude position of the ocean, its relative isolation from other oceans, permanent ice cover, inflow of warm Atlantic waters, and river runoff.
In winter, under the ice, the temperature of surface waters is 1.2...-1.7 °C. In the Norwegian and Barents Seas it is 0...+3 °C. In summer, the temperature rises, but under the ice it remains negative; in ice-free areas - 0 °С. In the Norwegian and Barents Seas, the temperature is 5-8 °С.
Salinity is not the same in different areas of the ocean and in different seasons of the year. In winter, in the under-ice layer - 34-35‰, near the island of Svalbard and in the Amerasian region - 31‰. In summer, salinity decreases due to the melting of ice. Near the pole the salinity is approximately 30‰; in the Amerasian region - 28‰, and off the coast of Siberia up to 20-10‰: the freshening effect of river waters influences.
One of the most characteristic natural features of the ocean is the permanent ice. In winter, almost 9/10 of the ocean is covered with ice. Only the spaces of the Greenland, Barents, Norwegian seas remain free of ice, which is explained by the influence of warm Atlantic waters. The predominant part of the ocean is occupied by drifting ice. Perennial drift ice is called pack. These are close-knit ice fields up to 5 m thick. The surface of the pack ice is hilly in places and flat in others.
Under the influence of winds and currents, ice is constantly moving (drifting). Fast ice is formed off the coast of continents, archipelagos, islands. In most areas, it is poorly developed and has a small width. Only in the Laptev Sea and in the East Siberian Sea is its width 600-700 m. Ocean Organic World is characterized by relative poverty of the species composition of flora and fauna. Algae, crustaceans, molluscs are common here. Of the mammals living in the waters of the ocean, the most widely represented are seals, seals, walruses, whales (narwhal whale, bowhead whale). The life of the inhabitants of the rocks is closely connected with the coastal part of the ocean. Fish-eating birds live here - gulls, guillemots, puffins, eiders. More than 150 species of fish live in the seas of the Arctic Ocean, some of which are of commercial importance: cod, haddock, halibut, herring, saury, sea bass.
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In all climatic zones are distinguished, with the exception of the northern polar (Arctic). The western and eastern parts of the Pacific Ocean differ significantly from each other and from the central regions of the ocean. As a result, within the belts, as a rule, physiographic regions are distinguished. In each specific region, natural conditions and processes are determined by the position in relation to the continents and islands, the depth of the ocean, the peculiarity of circulation and water, etc. In the western part of the Pacific Ocean, marginal and interisland seas are usually distinguished as physiographic regions, in the eastern - zones of intense upwelling.
Northern subpolar (subarctic) belt
Unlike , the Pacific part of the belt is quite isolated from the influence. The belt occupies most of the Bering and Okhotsk Seas.
In autumn and winter, the surface layer of water cools to the freezing point, and large masses of ice form. Cooling is accompanied by salinization of waters. In summer, sea ice gradually disappears, the thin upper layer rises to 3-5°C, in the south - up to 10°C. Cold water remains below, forming an intermediate layer formed as a result of winter cooling. Thermohaline convection, summer heating and water desalination (30-33% o) as a result of ice melting, the interaction of warm jets (Aleutian) with cold subpolar waters determine the relatively high content of nutrients in surface waters and the high bioproductivity of the subarctic belt. Nutrients are not lost at great depths, since vast shelves are located within the water area. Two regions stand out in the subarctic zone: the Bering Sea and the Sea of Okhotsk, rich in valuable commercial fish, invertebrates and marine animals.
northern temperate zone
In the Pacific Ocean, it covers vast areas from Asia to North America and occupies an intermediate position between the main areas of formation of cold subarctic and warm subtropical and tropical waters.
In the west of the belt, the warm Kuroshio Current and the cold Kuril Current (Oyashio) interact. From the streams formed with mixed water, the North Pacific Current is formed, which occupies a significant part of the water area and carries huge masses of water and heat from west to east under the influence of the westerly winds prevailing here. Water temperatures fluctuate greatly throughout the year in the temperate zone. In winter, near the coast, it can drop to 0°C, in summer it rises to 15-20°C (up to 28°C in the Yellow Sea). Ice forms only in limited inland areas of shallow seas (for example, in the northern part of the Sea of Japan). In winter, vertical thermal convection of waters develops with the participation of intense wind mixing: cyclonic activity is active in temperate latitudes. The high content of oxygen and nutrients in the water ensures a relatively high bioproductivity, and its value in the northern part of the belt (subpolar waters) is higher than in the southern part (subtropical waters). The salinity of the waters in the northern half of the water area is 33% o, in the southern half it is close to the average - 35% o. The western part of the belt is characterized by monsoon circulation, sometimes typhoons come here. Within the belt, the areas of the Japan and Yellow Seas and the Gulf of Alaska stand out.
Northern subtropical belt
It is located between the westerly winds of temperate latitudes and the trade winds of equatorial-tropical latitudes. The middle part of the water area is surrounded by the northern subtropical ring of currents.
Due to the prevailing sinking of the air and its stable stratification within the belt, there is usually a clear sky, a small amount of precipitation and relatively dry air. There are no prevailing air currents, the winds are weak and changeable, and calms are characteristic. Evaporation is very high due to the dryness of the air and high temperatures, and consequently, the salinity of the waters is increased - up to 35.5% o in the open part of the ocean. The water temperature in summer is about 24-26°C. The density of waters in winter is significant, and they sink under the warmer and lighter waters of low latitudes. The sinking of surface waters is compensated not so much by the rise of deep waters as by their inflow from the north and south (subtropical convergence), which is facilitated by the anticyclonic circulation. Strong warming of the ocean in summer causes a decrease in the density of the surface layer, subsidence stops, and a stable stratification of waters is created. As a result, the belt has a low bioproductivity, since neither in winter nor in summer does the water rise, the surface layers are not enriched with nutrients. The eastern part of the belt differs sharply from the main water area. This is a zone of the California current, characterized by upwelling and high bioproductivity and allocated to a separate physical and geographical region. In the western part of the subtropical belt, the region of the East China Sea with its own specifics of atmospheric (monsoon) and hydrological regimes and the region of the Kuroshio Current stand apart.
Northern tropical belt
This belt stretches from the coast of Indochina to the coast of Mexico and Central America. Steady trade winds of the Northern Hemisphere dominate here.
In summer, when the zone of action of the trade winds shifts to the north, equatorial air enters the belt with unstable stratification, high humidity, cloudiness and heavy rains. Winter is relatively dry. Storms in tropical latitudes are infrequent, but typhoons often come here. A significant part of the water area is occupied by the Northern Equatorial Current, which carries surface waters to the western part of the water area. The heat accumulated by them also moves in this direction. On the contrary, the relatively cold waters of the compensatory California current enter the eastern part of the ocean. In general, the surface tropical waters are characterized by high temperatures - 24-26°C in winter and 26-30°C in summer. Salinity on the surface is close to average and decreases towards the equator and the eastern margin of the ocean. In summer it drops somewhat due to frequent rains. Under the surface layer of water with high temperature, medium salinity and low density lie subsurface colder waters with high salinity and high density. Even lower are intermediate waters with low temperature, low salinity and high density. As a result, stable stratification is created in the upper layers throughout the year, the vertical mixing of waters is weak, and their bioproductivity is low. But the species composition of the organic world of warm tropical waters is very diverse. In the northern tropical zone, areas of the South China, Philippine Seas and the Gulf of California are distinguished.
equatorial belt
This belt in the Pacific Ocean is widely represented. This is the zone of convergence of the trade winds of the Northern and Southern hemispheres with a calm zone, where weak easterly winds are observed. Intense thermal air convection develops here, and heavy rains fall throughout the year.
The main surface current in this belt is compensatory with respect to the trade winds. The Cromwell subsurface current is pronounced, which moves eastward (from New Guinea to Ecuador). Surface waters are very hot throughout the year (up to 26-30°C). Seasonal temperature fluctuations are insignificant. Salinity is low - 34.5-34% o and below. The rise of waters prevails in the eastern and central parts of the ocean, in some places they sink. On the whole, uplift prevails over subsidence, and the surface layers are constantly enriched with nutrients. The waters are quite fertile, and in the equatorial zone there is an exceptionally large species diversity of the organic world. But the total number of organisms in equatorial waters (as well as in tropical waters) is less than in middle and high latitudes. Within the belt, areas of the Australo-Asian seas and the Gulf of Panama are distinguished.
Southern tropical belt
It occupies a vast expanse of water between Australia and Peru. This is the trade wind zone of the Southern Hemisphere. The alternation of rainy summer and dry winter periods is quite clearly expressed. Hydrological conditions are determined by the South Equatorial Current.
Surface water temperatures are as high as in the northern tropical zone. Salinity is slightly higher than in equatorial waters (35-35.5% o). Vertical mixing in the upper layers, as in the northern analogue belt, is very weak. The primary and commercial productivity of the water area is low. The exception is the eastern part of the ocean - the zone of action of the Peruvian current with a relatively stable and intense upwelling. This is one of the most highly productive areas not only in the Pacific, but also in. Tropical waters are the kingdom of corals. In the western and middle parts of the belt there are several thousand large and small islands, most of them of coral origin. Off the coast of Australia is the Great Barrier Reef. Tropical hurricanes are not uncommon in the western part of the ocean. This part of the belt is influenced by the monsoonal circulation. In the west, the areas of the Coral Sea and the Great Barrier Reef stand out, in the east - the Peruvian region.
Southern subtropical belt
This belt extends from southeastern Australia and Tasmania to the coast of South America between 20° and 35° S. sh. The axis of the belt is the zone of subtropical convergence of the waters of the Southern Equatorial Current and the northern streams of the Western Winds Current. The water area is under the influence of the South Pacific baric maximum.
The main natural processes are the same as in the northern analogous belt: the lowering of air masses, the formation of a high pressure area with weak unstable winds, cloudless skies, dry air, low precipitation and water salinization. It is here that the maximum salinity of surface waters for the open part of the Pacific Ocean is 35.5-36% o. The main area of formation of the subtropical water mass is a zone of high evaporation in the eastern part of the belt (near Easter Island). The warm and salty one spreads from here to the west and north, gradually sinking under the warmer and desalinated surface water. The biological productivity of the waters of the belt has not yet been sufficiently studied. It is believed that it cannot be high. On the eastern margin of the water area there is a zone of subtropical upwelling of the Peruvian current, where the biomass is still large, although the surge and rise of water occur in a weakened (compared to the tropical belt) form. Here, areas of the coastal waters of Northern and Central Chile are distinguished, and in the western part of the belt, the Tasman Sea region is isolated.
southern temperate zone
It includes the greater northern part of the circumpolar current of the West Winds. Its southern boundary runs along the edge of the spread of sea ice in September in the region of 61-63°S. sh. The southern temperate zone is an area dominated by western air transport, significant cloudiness, and frequent rains (especially in the autumn-winter period).
Stormy weather (“roaring forties” and no less stormy fifties latitudes) is very characteristic. Temperatures of waters on the surface in - 0-10°C, in - 3-15°C. Salinity - 34.0-34.5% o, off the coast of Southern Chile, where there is a lot of precipitation, - 33.5% o. The main process in the temperate latitudes of the southern part of the Pacific Ocean is the same as in the northern part - the transformation of warm low-latitude and cold high-latitude air and water masses coming here, their constant interaction and, as a result, greater dynamism of the ocean. The zone of convergence of two jets of the circumpolar current runs at about 57°S. sh. The waters of the belt are relatively fertile. Within the belt, the area of coastal waters of Southern Chile (South Chilean) is distinguished.
Southern subpolar (subantarctic) belt
The boundaries of this belt in the Pacific Ocean are shifted to the south (by 63-75 ° S) compared to other oceans. The water area is especially wide in the area of the Ross Sea, which penetrates deep into the massif of the Antarctic continent. In winter, the waters are covered with ice.
The sea ice boundary migrates 1000-1200 km during the year. In this belt, the flow of waters from west to east dominates (the southern jet of the current of the West Winds). In the southern part of the belt, a westward current is observed. The water temperature in winter is close to the freezing point, in summer - from 0 to 2°C. Salinity in winter is about 34% o, in summer, as a result of ice melting, it decreases to 33.5% o. In winter, deep waters form, which fill the basins of the ocean. In the belt, the interaction of Antarctic waters and waters of temperate latitudes of the Southern Hemisphere takes place. Bioproductivity is high. In commercial terms, the water area has not been studied enough.
South polar (Antarctic) belt
Within the Pacific Ocean, it is quite extensive. In the Ross Sea, the waters of the ocean go far beyond the Antarctic Circle, almost to 80 ° S. sh., and taking into account ice shelves - even further. To the east of McMurdo Bay, the cliff of the Ross Ice Shelf (Great Ice Barrier) stretches for hundreds of kilometers.
The southern part of the Ross Sea is a unique water area occupied by a giant ice shelf slab 500 km long from north to south and 500 m thick on average. In the Amundsen and Bellingshausen seas, the Antarctic belt approximately coincides with the shelf zone. here it is severe, with strong winds from the continent, frequent occurrences of cyclones, storms. As a result of strong winter cooling, many very cold waters with a salinity close to normal are formed. Plunging and spreading to the north, they form the deep and bottom water masses of the ocean basins up to the equator and beyond. On the surface of the ocean, the most typical natural processes for the belt are ice phenomena and glacial runoff from the continent. The bioproductivity of cold Antarctic waters is low, and their commercial value has not been sufficiently studied. peculiar.
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