The Atlantic Ocean is the second largest and deepest. Its area is 91.7 million km2. The average depth is 3597 m, and the maximum depth is 8742 m. The length from north to south is 16,000 km.
Geographical location of the Atlantic Ocean
The ocean stretches from the North Arctic Ocean in the north to the shores of Antarctica in the south. In the south, the Drake Passage separates the Atlantic from the Pacific. A characteristic feature of the Atlantic Ocean is the many inland and marginal seas in the Northern Hemisphere, the formation of which is mainly associated with tectonic movements of lithospheric plates. (Determine the lithospheric plates within which the ocean is located on the map "Structure of the Earth's crust".) The largest of the seas: Baltic, Black, Azov, Irish, North, Sargassovo, Norwegian, Mediterranean. There are more than 10 seas in the Atlantic Ocean. (Find on physical map Sargasso and Mediterranean seas, compare their natural features.)
The Atlantic Ocean and its seas are washed by five continents. More than 70 states (in which more than 2 billion people live) and 70% of the largest cities in the world are located on its shores. Therefore, the most important shipping routes pass across the Atlantic. The ocean is called "the element that unites peoples."
Bottom relief The Atlantic Ocean is, according to scientists, the youngest and more leveled. More than 18,000 km of the Mid-Atlantic Ridge runs from north to south of the ocean. Along the ridge is a rift system where the largest volcanic island, Iceland, was formed. Depths of 3000-6000 m prevail within the waters of the Atlantic Ocean. In contrast to the Pacific, there are few deep-water trenches in the Atlantic Ocean. The deepest is Puerto Rico (8742 m) in the Caribbean Sea. There is a well-defined shelf zone within the ocean, especially in the Northern Hemisphere off the coast of North America and Europe.
Atlantic climate
The ocean is located in almost all geographic zones. This determined the diversity of its climate. In the north, in the area of the island of Iceland, an area of low pressure is formed over the ocean, which is called the Icelandic minimum. The prevailing winds over the ocean in tropical and subequatorial latitudes are trade winds, in moderate latitudes - westerly winds. Differences in atmospheric circulation cause uneven distribution of precipitation. (Use the Annual Precipitation Map to study the distribution of precipitation in the Atlantic Ocean.) Average Temperature surface waters in the Atlantic Ocean is +16.5 ° С. The ocean has the saltiest surface waters, with an average salinity of 35.4 ‰. The salinity of surface waters varies greatly in the north and south.
The maximum salinity reaches 36-37 ‰ and is typical for tropical regions with low annual rainfall and strong evaporation. The decrease in salinity in the north and south of the ocean (32-34 ‰) is explained by the melting of icebergs and floating sea ice.
Currents in the Atlantic Ocean act as powerful carriers of thermal energy. Two systems of currents have formed in the ocean: clockwise in the Northern and counterclockwise in the Southern hemisphere. In the tropical latitudes of the ocean, trade winds cause powerful surface currents from east to west on both sides of the equator - the North Trade and South Trade currents. Crossing the ocean, these currents have a warming effect on the eastern shores of North and South America. A powerful warm current, the Gulf Stream ("current from the Gulf"), originates in the Gulf of Mexico and reaches the islands of Novaya Zemlya. The Gulf Stream carries 80 times more water than all the rivers in the world. The thickness of its flow reaches 700-800 m. This mass of warm water with temperatures up to +28 ° C moves at a speed of about 10 km / h. North of 40 ° N. NS. The Gulf Stream turns to the shores of Europe, and here it is called the North Atlantic Current. The water temperature of the current is higher than that of the ocean. Therefore, warmer and wetter air masses dominate over the current and cyclones are formed. The Canary and Benguela currents have a cooling effect on the western coast of Africa, and the cold Labrador Current on the east coast of North America. The eastern shores of South America are washed by the warm Brazilian current.
The ocean is characterized by rhythmically recurring ebbs and flows. The highest tidal wave in the world reaches 18 m in the Bay of Fundy off the coast.
Natural Resources and Environmental Issues of the Atlantic Ocean
The Atlantic Ocean is rich in a variety of mineral resources. The largest oil and gas fields have been explored in the shelf zone off the coast of Europe (North Sea region), America (Gulf of Mexico, Maracaibo lagoon) and others (Fig. 43). Phosphorite deposits are significant; ferromanganese nodules are less common.
Organic world Atlantic Ocean in terms of the number of species, it is poorer than the Pacific and Indian Oceans, but has a higher productivity.
In the tropical part of the ocean, the greatest diversity of the organic world is noted, the number of fish species is measured in tens of thousands. These are tuna, mackerel, sardines. In temperate latitudes, herring, cod, haddock, halibut are found in large quantities. Jellyfish, squid, octopus are also inhabitants of the ocean. The cold waters are inhabited by large marine mammals (whales, pinnipeds), various types of fish (herring, cod), crustaceans. The main fishing areas are northeast off the coast of Europe and northwest off the coast of North America. The wealth of the ocean is brown and red algae, kelp.
In terms of economic use, the Atlantic Ocean ranks first among other oceans. The use of the ocean plays an important role in the development of the economy of many countries of the world (Fig. 44).
The vastness of the Atlantic Ocean is most polluted by oil and oil products. Water purification is carried out using modern methods, the discharge of production waste is prohibited.
The features of the geographical position of the Atlantic Ocean are its great elongation from north to south, the presence of internal and marginal seas. The Atlantic Ocean plays a leading role in the implementation of international economic relations. For five centuries, it ranks first in the world's shipping.
The Atlantic Ocean is the second largest ocean after the Pacific. Its area is much smaller and amounts to 91.6 million km². About a quarter of this area falls on the shelf seas. The coastline is very indented, primarily in the Northern Hemisphere, in the Southern it is relatively flat. The ocean washes all continents except Australia. Islands located in the ocean area are located near the continents. The Atlantic is washed by the largest island on the planet - Greenland.
This ocean began to be mastered by European civilization earlier than all others, and therefore is of great importance for Europe. It got its name in honor of the titan Atlas, since he held the firmament not far from the mythical garden of the Hesperides, located at the edge of the earthly firmament, just where the Atlantic Ocean went - as the ancient Greeks believed. Also, its name is associated with the legendary Atlantis, according to legend, was located somewhere in the waters of the Atlantic and irretrievably sunk in its depths. Perhaps the myth of Atlantis has a real foundation. As a result of the movement of the earth's crust, some of the Mediterranean islands went under water, along with temples, palaces and columns erected by ancient civilizations. Over the course of thousands of years, new states arose and disappeared along the shores of the Mediterranean Sea: Crete, Mycenae, the policies of Ancient Greece, Phenicia, Carthage, and finally Rome. Ancient Rome from a small city of the state for several centuries turned into the strongest Mediterranean power. In the 1st-2nd centuries AD, Rome controlled the entire Mediterranean coast. The Romans even called it "Mare Nostrum" or "Our Sea". In the Middle Ages, the most important trade routes between Europe, Asia and Africa passed here. Countries that had access to the Atlantic began to colonize more and more remote corners of the planet. With the discovery of America, the Atlantic Ocean became a link between the Old and New Worlds. And today its economic and transport importance is still very high.
Speaking about the relief of the Atlantic seabed, it should be said that this is a young ocean. It was formed only in the Mesozoic era, when the single continent of Pangea began to split into pieces, and America separated from Africa. The Mid-Atlantic Ridge stretches across the entire ocean from north to south. The island of Iceland in the north is nothing more than the exit of this ridge to the surface, which is why Iceland is a country of geysers and volcanoes. Now the ocean continues to expand, and the continents are moving away from each other at a rate of several centimeters per year. The Mediterranean Sea is the largest inland sea of the ocean in its origin, along with the Black, Caspian and The Azov seas are the remains of the ancient tropical ocean Tethys, which closed after the collision of Africa and Eurasia. In the future, in millions of years, these seas will completely disappear, and mountains will form in their place.
The climate of the Atlantic Ocean is very diverse, because it, like the Pacific Ocean, is located in all climatic zones planets. However, the surface water temperature is lower here than in the Pacific and Indian Oceans. This is due to the constant cooling effect of melting ice brought here from the Arctic. The currents facilitate the movement of floating ice, the boundary of which reaches 40 ° N. At the same time, the salinity of the Atlantic is very high, since most large areas the ocean has in the tropics, where evaporation is great and there is very little rainfall. The evaporated moisture is carried away by the winds to the continents, due to the relative narrowness of the ocean, without having time to fall over its water area.
The organic world of the Atlantic is poorer than the world of the Pacific. The reason for this is the colder climate and its youth. But with a small variety, the number of fish and other marine animals is significant. The shelf occupies large areas here, and therefore favorable spawning grounds for many commercial fish are created: cod, herring, mackerel, sea bass, capelin. Whales and seals are found in polar waters. The unique Sargasso Sea is located off the coast of North America, it has no shores, and its borders are formed by ocean currents. The sea surface is covered with sargassum algae, the sea waters are poor in plankton. Once the Sargasso Sea was also the most transparent on the planet, however, now its surface is heavily polluted with oil products.
Due to its natural conditions, the Atlantic Ocean is the most productive in terms of the amount of biological resources. Most of the fish catch falls on its northern part, but too active fishing has led to a noticeable reduction in the amount of resources in last years... There are a lot of oil and gas reserves on the Shelf, especially in the Gulf of Mexico, however, the 2010 accident showed what colossal damage to the ecology of the ocean is caused by their production. There are also large hydrocarbon deposits on the shelf of the North Sea off the coast of Europe. Today, the ocean is already very heavily polluted by human activities and is not capable of self-cleaning at such a rate. The task of the developed states of the Earth for the coming decades is to protect and preserve its natural resources.
Its great length (16 thousand km) from north to south - from arctic to Antarctic latitudes and a relatively small width, especially in near-equatorial latitudes, where it does not exceed 2900 km. The average depth of the ocean is 3597 m, the maximum is 8742 m (the Puerto Rico trench). It was the Atlantic Ocean, with its peculiarities of configuration, age and bottom topography, that served as the basis for the development of the theory of continental drift - the theory of mobilism - the movement of lithospheric plates. It was formed as a result of the split of Pangea, and then the separation of Laurasia and Gondwana. The main processes of the formation of the Atlantic took place in the Cretaceous period. The axial zone of the ocean is the "S" -shaped Mid-Atlantic ridge, which rises above the bottom of the basin by an average of 2000 m, and in Iceland, taking into account its surface part, by more than 4000 m. The Mid-Atlantic ridge is young, tectonic processes in it are active and up to the present time, as evidenced by earthquakes, surface and underwater volcanism.
Unlike other oceans in the Atlantic, there are significant areas of continental crust (off the coast of Scotland, Greenland, the Blake Plateau, at the mouth of the La Plata), which testifies to the youth of the ocean.
In the Atlantic, as in other oceans, planetary morphostructures are distinguished: the underwater margins of the continents (shelf, continental slope and continental foot), transition zones, mid-ocean ridges and the ocean floor with a series of basins.
The characteristic features of the Atlantic Ocean shelf are its two types (glacial and normal) and unequal width off the coast of North and South America, Europe and Africa.
The glacial shelf is confined to the areas of development of modern and cover Quaternary glaciation, it is well developed in the northern part of the Atlantic, including the North and Baltic seas, and off the coast of Antarctica. The glacial shelf is characterized by great dissection and widespread development of glacial exaration and accumulative relief. South of Newfoundland and Nova Scotia from the American side and the English Channel from the European, the glacial shelf is replaced by a normal one. The surface of such a shelf is leveled by accumulative-abrasion processes, which, from the beginning of the Quaternary period to the present, affect the bottom topography.
The African shelf is very narrow. Its depths are from 110 to 190 m. In the south (near Cape Town) it is terraced. The South American shelf is narrow, with depths up to 90 m, leveled, gently sloping. In some places there are terraces and weakly expressed underwater valleys of large rivers.
The continental slope of the normal shelf is leveled, and passes towards the ocean either by a series of terraces with slopes of 1-2 °, or by a steep scarp with slopes of 10-15 °, for example, near the Florida and Yucatan Peninsulas.
From Trinidad to the mouth of the Amazon, it is a dissected scarp with depths of up to 3500 m with two ledges: the Guiana and Amazon fringe plateaus. To the south, the scarp is stepped with block forms. Off the coast of Uruguay and Argentina, the slope is concave and heavily dissected by canyons. The continental slope off the coast of Africa is of a blocky nature with well-defined steps near the Cape Verde Islands and the delta of the river. Niger.
Transition zones are areas of junction of lithospheric plates with underthrust (subduction). They occupy a small place in the Atlantic Ocean.
One of these zones - a relic of the Tethys Ocean - is located in the Caribbean-Antilles and continues into the Mediterranean Sea. It is torn apart by the expanding Atlantic. In the west, the role of the marginal sea is played by the Caribbean Sea, the Great and Lesser Antilles form island arcs, they are accompanied by deep-sea trenches - Puerto Rico (8742 m) and Cayman (7090 m). In the south of the ocean, the Scotia Sea is bordered from the east by the South Antilles underwater ridge with chains of volcanic islands forming an arc (South Georgia, South Sandwich, etc.). At the eastern foot of the ridge, there is a deep-water trench - South Sandwich (8264 m).
The mid-ocean ridge is the brightest geographic feature Atlantic Ocean.
The northernmost link of the Mid-Atlantic Ridge proper - the Reykjanes Ridge - at 58 ° N. NS. limited by the sublatitudinal Gibbs fault zone. The ridge has a distinct rift zone and flanks. Fr. Iceland, the crest of the ridge has steep scarps, and the Gibbs Fault is a double chain of troughs with structures displaced up to 350 km.
Area about. Iceland, on the surface of the North Atlantic Ridge, is a very active rift structure passing through the entire island, with a manifestation of spreading, as evidenced by the basaltic composition of the entire ridge ridge, youth sedimentary rocks, symmetry of anomalous magnetic lines, increased heat flux from the bowels, the presence of numerous small earthquakes, ruptures of structures (transform faults), etc.
On a physical map, a drawing of the Mid-Atlantic Ridge can be traced across the islands: about. Iceland, on the eastern slope - the Azores, on the equator - about. St. Paul, southeast - about. Ascension, further on. Saint Helena, Fr. Tristan da Cunha (between Cape Town and Cape Town) and Fr. Bouvet. Having skirted Africa, the Mid-Atlantic Ridge joins the ridges.
The northern part of the Mid-Atlantic Ridge (up to the Azores) is 1100-1400 km wide and presents an arc convex to the east.
This arc is cut by transverse faults - Faraday (49 ° N), Maxwell (48 ° N), Humboldt (42 ° N), Kurchatov (41 ° N). The flanks of the ridge are gently declining surfaces with block-block-ridge relief. To the north-east of the Azores there are two ridges (Polisser and Mesyatseva). The Azores plateau is located at the site of a triple junction of plates (oceanic and two continental). The southern part of the North Atlantic Ridge to the equator also looks like an arc, but it faces the convex part to the west. The width of the ridge here is 1600-1800 km; towards the equator it narrows to 900 km. Along its entire length, the rift zone and flanks are dissected by transform faults in the form of troughs, some of which extend into the adjacent basins of the ocean floor. The best studied are the Oceanograf, Atlantis, and Romanov transform faults (at the equator). The displacement of structures in the faults is in the range of 50-550 km with a depth of up to 4500 m, and in the Romanche trench - 7855 m.
South Atlantic ridge from the equator to about. Bouvet is up to 900 km wide. Here, as well as in the North Atlantic, a rift zone with depths of 3500-4500 m is developed.
Faults in the southern part - Chain, Ascension, Rio Grande, Falkland. On the eastern flank, on the underwater plateaus, rise the mountains of Bagration, Kutuzov, Bonaparte.
In Antarctic waters, the African-Antarctic ridge is not wide - only 750 km, dissected by a series of transform faults.
A characteristic feature of the Atlantic is a fairly clear symmetry of the orographic structures of the bed. On both sides of the Mid-Atlantic Ridge, there are depressions with a flat bottom, successively replacing each other from north to south. They are separated by small underwater ridges, rapids, uplifts (for example, Rio Gran de, Kitovy), successively replacing each other from north to south.
In the extreme northwest there is the Labrador Basin with a depth of more than 4000 m - a flat abyssal plain with a thick two-kilometer sedimentary cover. Further - the Newfoundland Basin (maximum depth more than 5000 m), with an asymmetrical bottom structure: in the west it is a flat abyssal plain, in the east - hilly.
The North American Basin is the largest in size. In the center is the Bermuda Plateau with a thick layer of sediments (up to 2 km). Cretaceous deposits have been uncovered by drilling, but geophysical data indicate that there is an even older formation under them. Volcanic mountains form the base of the Bermuda Islands. The islands themselves are composed of coral limestones and represent a giant atoll, which is a rarity for the Atlantic Ocean.
To the south is the Guyana Basin, part of which is the Para Rapid. It can be assumed that the threshold is of accumulative origin and is associated with the accumulation of material from turbidity flows fed by the huge removal of solid sediments from the Amazon (more than 1 billion tons per year).
Further south is the Brazilian Basin with a ridge of seamounts, at the top of one of which is the only coral atoll in the South Atlantic, Rocas.
The largest depression in the South Atlantic - the African-Antarctic - from the Scotia Sea to the Kerguelen Upland, its length is 3500 miles, its width is about 800 miles, and the maximum depth is 6972 m.
In the eastern part of the ocean floor, there is also a series of basins, often separated by volcanic uplifts: in the region of the Azores, at the Cape Verde Islands and the Cameroon Fault. The basins of the eastern part (Iberian, Western European, Canary, Angolan, Cape) are characterized by the oceanic type of the earth's crust. The sedimentary cover of the Jurassic and Cretaceous age is 1–2 km thick.
Ridges play an important role in the ocean as environmental barriers. The basins differ from each other in bottom sediments, soils, and a complex of minerals.
Bottom sediments
Among the bottom sediments of the Atlantic, the most common are foraminiferal silts, which occupy about 65% of the ocean floor area, followed by deep-sea red and red-brown clays (about 20%). Terrigenous deposits are widespread in the basins. The latter are especially characteristic of the Guinean and Argentinean basins.
Bottom sediments and bedrocks of the ocean floor contain a wide range of minerals. The Atlantic Ocean is rich in oil and gas fields.
The most famous are the deposits of the Gulf of Mexico, North Sea, Biscay and Guinea Gulfs, Maracaibo Lagoon, coastal regions near the Falkland (Malvinas) Islands. New fields and gas are discovered annually: off the east coast of the United States, in the Caribbean and North Seas, etc. By 1980, 500 deposits were discovered on the shelf off the coast of the United States, and more than 100 in the North Sea. drilling. In the Gulf of Mexico, for example, "Glomar Challenger" drilled and discovered a salt dome at a depth of 4000 m, and off the coast of Iceland, in an area with sea depths from 180 to 1100 m and a thick four-kilometer sediment cover, an oil-bearing well was drilled with a flow rate of 100-400 tons in day.
In coastal waters with powerful ancient and modern alluvium, there are deposits of gold, tin, and diamonds. Monazite sands are mined off the coast of Brazil. This is the largest field in the world. There are known deposits of ilmenite and rutile off the coast of Florida (USA). The largest placers of ferromanganese nodules and phosphorite deposits belong to the regions of the South Atlantic.
Features of the climate of the Atlantic Ocean
The climate of the Atlantic Ocean is largely determined by its great meridional length, the peculiarities of the formation of the baric field, the peculiarity of the configuration (there are more water areas in temperate latitudes than in equatorial-tropical ones). On the northern and southern outskirts, there are huge regions of cooling and the formation of centers of high atmospheric. Permanent areas of low pressure in the equatorial and temperate latitudes and high pressure in subtropical latitudes are also formed over the ocean.
These are the Equatorial and Antarctic Depressions, the Icelandic Low, the North Atlantic (Azores) and South Atlantic Highs. The position of these centers of action changes with the seasons: they shift towards the summer hemisphere.
Trade winds blow from subtropical highs to the equator. The stability of the direction of these winds is up to 80% per year, the strength of the winds is more variable - from 1 to 7 points. In the temperate latitudes of both hemispheres, the winds of the western components dominate, at significant speeds, often turning into a storm in the Southern Hemisphere - the so-called "roaring forties" latitudes.
Atmospheric pressure distribution and features air masses affect the nature of cloudiness, regime and amount of precipitation. Cloudiness over the ocean varies by zones: the maximum amount of clouds at the equator with a predominance of cumulus and cumulonimbus forms, the least cloudiness - in tropical and subtropical latitudes, in temperate areas the amount of clouds increases again - stratus and nimbostratus forms prevail here.
Very characteristic of the temperate latitudes of both hemispheres (especially the Northern) are dense fogs formed when warm air masses and cold ocean waters come into contact, as well as when cold and warm currents meet at about. Newfoundland. Especially dense summer fogs in this area complicate navigation, especially since icebergs are often found there. In tropical latitudes, fogs are most likely near the Cape Verde Islands, where dust carried out from the Sahara serves as condensation nuclei for atmospheric water vapor. Fogs are also common near the southwestern coast of Africa in the region of the climate of "wet" or "cold" deserts.
A very dangerous phenomenon in the tropical latitudes of the ocean is tropical cyclones that cause hurricane winds and heavy rainfall. Tropical cyclones often develop from small depressions moving from the African continent to the Atlantic Ocean. Gaining strength, they become especially dangerous for the West Indies and southern North America.
Temperature regime
On the surface, the Atlantic Ocean is generally colder than the Indian Ocean due to its long north-south extension, a small width at the equator and a wide connection with.
The average surface water is 16.9 ° С (according to other sources - 16.53 ° С), while in the Tikhiy - 19.1 ° С, in the Indian - 17 ° С. The average temperature of the entire water mass of the Northern and Southern Hemispheres also differs. Mainly due to the Gulf Stream, the average water temperature in the North Atlantic (6.3 ° C) is slightly higher than in the South (5.6 ° C).
Seasonal temperature changes are also well traced. The lowest temperature is recorded in the north and in the south of the ocean, and the highest is the opposite. However, the annual temperature amplitude at the equator is no more than 3 ° С, in subtropical and temperate latitudes - 5-8 ° С, in circumpolar ones - about 4 ° С. The daily fluctuations in the temperature of the surface layer are even less - on average, 0.4-0.5 ° C.
The horizontal temperature gradient of the surface layer is significant in places where cold and warm currents meet, for example, East Greenland and Irminger, where a temperature difference of 7 ° C at a distance of 20-30 km is a common phenomenon.
Annual temperature fluctuations are clearly traced in the surface layer up to 300-400 m.
Salinity
The Atlantic Ocean is the saltiest of all. The salt content in the waters of the Atlantic averages 35.4%, which is more than in other oceans.
The highest salinity is observed in tropical latitudes (according to Gembel) - 37.9% o, in the North Atlantic between 20 and 30 ° C. sh., in the South - between 20 and 25 ° S. NS. The trade wind circulation prevails here, there is little precipitation, evaporation is a layer of 3 m. Fresh water from the land almost does not come. Slightly higher average salinity is also in the temperate latitudes of the Northern Hemisphere, where the waters of the North Atlantic Current rush. Salinity in near-equatorial latitudes is 35% o. Changes in salinity with depth are traced: at a depth of 100-200 m, it is 35.4% o, which is associated with the Lomonosov subsurface current. It was found that the salinity of the surface layer does not coincide in some cases with the salinity at depth.
Sharp changes in salt content are also observed when currents of different temperatures meet. For example, south of about. Newfoundland, when the Gulf Stream and the Labrador Current meet at a small distance, salinity falls from 35% o to 31-32% o.
The existence of underground fresh waters in the Atlantic Ocean - submarine sources (according to I.S.Zetsker) - is an interesting feature of it. One of them has long been known to sailors, it is located east of the Florida Peninsula, where ships replenish fresh water supplies. This is a 90-meter "fresh window" in the salty ocean. Here, a typical phenomenon of unloading of an underground source occurs in the area of tectonic faults or areas of karst development. When the head of groundwater exceeds the pressure of the column sea water, unloading occurs - the outpouring of groundwater onto the surface. A well was recently drilled on the continental slope of the Gulf of Mexico off the coast of Florida. While drilling a well from a depth of 250 m, a column of fresh water 9 m high escaped. The search and study of submarine sources are just beginning.
Optical properties of water
Transparency, which determines the illumination of the bottom, the nature of heating of the surface layer, is the main indicator of optical properties. It varies widely, which is why the albedo of water also changes.
The transparency of the Sargasso Sea is 67 m, the Mediterranean - 50, the Black - 25, the North and Baltic - 13-18 m. The transparency of the waters of the ocean itself far from the coast, in the tropics is 65 m. The optical structure of the waters of the tropical latitudes of the Atlantic is especially interesting. The waters here are characterized by a three-layer structure: an upper mixed layer, a layer of reduced transparency and deep transparent ones. Depending on hydrological conditions, the thickness, intensity and a number of features of these layers vary in time and space. The depth of the layer of maximum transparency decreases from 100 m near the coast North Africa up to 20 meters off the coast of South America. This is due to the turbidity of the waters at the mouth of the Amazon. The waters of the central part of the ocean are homogeneous and transparent. The structure of transparency is also changing in the upwelling zone off the coast of South Africa due to the increased content of plankton. The boundaries between layers with different opacities are often blurry and fuzzy. Against the mouth of the river. Congo also has a three-layer profile, to the north and south - a two-layer one. In the Guinea sector of the Atlantic, the picture is the same as at the mouth of the Amazon: a lot of solid particles are carried into the ocean by rivers, in particular the river. Congo. Here is the place of convergence and divergence of currents, deep transparent waters rise along the continental slope.
Dynamics of waters
They learned about the existence in the ocean relatively recently, even about the Gulf Stream became known only at the beginning of the 16th century.
There are currents of various origins in the Atlantic Ocean: drift currents - North and South Tradewinds, West Drift or West Winds (with a flow rate of 200 sverdrups), stock (Florida), tidal currents. In the Bay of Fundy, for example, the tide reaches record levels (up to 18 meters). There are also density countercurrents (for example, the Lomonosov countercurrent is subsurface).
Powerful surface currents in the tropical latitudes of the ocean are caused by trade winds. These are the North and South Trade winds moving from east to west. They fork off the eastern shores of the Americas. In summer, the inter-trade countercurrent manifests itself most effectively, its axis moves from 3 ° to 8 ° C. NS. The North Passat Current near the Antilles splits into branches. One goes to the Caribbean Sea and the Gulf of Mexico, the other - the Antilles branch merges with the Florida branch and, leaving the bay, forms a giant warm Gulf Stream. This current, together with its branches, has a length of more than 10 thousand km, the maximum discharge is 90 sverdrups, the minimum is 60, the average is 69. The water discharge in the Gulf Stream is 1.5-2 times higher than that of the largest currents of the Pacific and Indian oceans - Kuroshio and Somali. The width of the stream is 75-100 km, the depth is up to 1000 m, the speed is up to 10 km / h. The boundary of the Gulf Stream is determined by the 15 ° C isotherm at a depth of 200 m. The salinity is more than 35% o, in the southern branch - 35.1% o. The main stream reaches 55 ° W. Before this segment, there is almost no transformation of the water mass on the surface; at a depth of 100-300 m, the flow properties do not change at all. At Cape Hatteras (Gateras), the waters of the Gulf Stream are divided into a series of narrow, strongly meandering streams. One of them, at a cost of about 50 sverdrups, goes to the Newfoundland Bank. From 41 ° W the North Atlantic current begins. In it, rings are observed - vortices moving in the direction of the general movement of the water.
The North Atlantic Current also "branches", the Portuguese branch separates from it, which merges with the Canary Current. In the north, the Norwegian branch is formed and further - the North Cape. The Irminger Current departs to the northwest and meets the cold drainage East Greenland Current. West Greenland in the south connects with the Labrador Current, which, mixing with the warm current, and leads to a deterioration in meteorological conditions in the area of the Newfoundland Bank. The water temperature in January is 0 ° С, in July it is 12 ° С. The Labrador current often carries icebergs into the ocean south of Greenland.
The Southern Passat Current off the coast of Brazil bifurcates into the Guiana and Brazilian Current, to the north, the Guiana Current merges with the North Passat Current. Brazilian in the south, about 40 ° S. NS. connects with the current of the West Winds, from which the cold Benguela current departs to the shores of Africa. It merges with the South Passat, and the southern ring of currents is closed. The cold Falklands is approaching the Brazilian from the south.
Discovered in the 60s of the XX century, the Lomonosov countercurrent has a direction from west to east, passes at a depth of 300-500 m in the form of a huge river several hundred kilometers wide.
In the southern part of the North Passat Current, anticyclonic eddies with a speed of 5.5 cm / sec were discovered. In the ocean there are eddies of large diameters - 100-300 km (average ones have a diameter of 50 km, small ones - 30 km). The discovery of these eddies, called synoptic, is of great importance for plotting the course of ships. Artificial satellites of the Earth are of great help in compiling maps showing the direction and speed of movement of synoptic eddies.
The dynamics of ocean waters has a huge energy potential, which is hardly used up to now. And although the ocean is in most cases weaker concentrated, less convenient for use than the energy of rivers, scientists believe that these are inexhaustible resources, constantly renewable. In the first place is the energy of the tides.
The first successfully operating tidal water mills were built in England (Wales) in the 10th-11th centuries. Since then, they have been continuously built on the shores of Europe and North America. However, serious energy projects appeared in the 1920s. Possibilities of using tides as energy sources are most likely off the coast of France, Great Britain, USA,. The first small tidal power plants are already in operation.
Work is underway to use the thermal energy of the oceans. The surface layer of water in tropical latitudes can heat up to insignificant seasonal fluctuations. At a depth of 300-500 m, the water temperature is only 8-10 ° C. Even more sharp drop in upwelling zones. The temperature difference can be used to generate energy in water-steam turbines. The first ocean experimental thermal station with a capacity of 7 MW was created by French scientists near Abidjan (Cote d'Ivoire).
ATLANTIC OCEAN (Latin name Mare Atlanticum, Greek? Τλαντ? Σ - meant the space between the Strait of Gibraltar and the Canary Islands, the whole ocean was called Oceanus Occidental is - Western Ocean), the second largest ocean on Earth (after the Pacific Ocean), part of the World Ocean. The modern name first appeared in 1507 on the map of the Lorraine cartographer M. Waldseemüller.
Physico-geographical sketch. General information... In the north, the border of the Atlantic Ocean with the Arctic Ocean basin runs along the eastern entrance of the Hudson Strait, then through the Davis Strait and along the coast of Greenland to Cape Brewster, through the Danish Strait to Cape Reidinupur on Iceland, along its coast to Cape Gerpir (Terpir), then to the Faroe Islands, then to the Shetland Islands and 61 ° north latitude to the coast of the Scandinavian Peninsula. In the east, the Atlantic Ocean is bounded by the shores of Europe and Africa, in the west - by the shores of North America and South America. The border of the Atlantic Ocean with the Indian Ocean is drawn along a line running from Cape Agulhas along the meridian of 20 ° east longitude to the coast of Antarctica. The border with the Pacific Ocean is drawn from Cape Horn along the meridian 68 ° 04 'West longitude or along the shortest distance from South America to the Antarctic Peninsula through the Drake Passage, from Oste Island to Cape Sternek. The South Atlantic Ocean is sometimes called the Atlantic Sector of the Southern Ocean, drawing the boundary along the subantarctic convergence zone (approximately 40 ° S latitude). In some works, the division of the Atlantic Ocean into the North and South Atlantic Oceans is proposed, but it is more customary to consider it as a single ocean. The Atlantic Ocean is the most biologically productive of the oceans. It contains the longest underwater oceanic ridge - the Mid-Atlantic ridge, the only sea that does not have solid shores, limited by currents - the Sargasso Sea; Bay of Fundy with the highest tidal wave; the Black Sea with a unique hydrogen sulfide layer belongs to the Atlantic Ocean basin.
The Atlantic Ocean stretches from north to south for almost 15 thousand km, its smallest width is about 2830 km in the equatorial part, the largest is 6700 km (along the parallel of 30 ° north latitude). The area of the Atlantic Ocean with seas, bays and straits is 91.66 million km 2, without them - 76.97 million km 2. The volume of water is 329.66 million km 3, without seas, bays and straits - 300.19 million km 3. The average depth is 3597 m, the greatest is 8742 m (the trench of Puerto Rico). The most easily accessible ocean shelf zone (with depths of up to 200 m) occupies about 5% of its area (or 8.6% if we take into account seas, bays and straits), its area is larger than in the Indian and Pacific Oceans, and much less than in the Arctic Ocean. Areas with depths from 200 m to 3000 m (continental slope zone) occupy 16.3% of the ocean area, or 20.7% taking into account the seas and bays, more than 70% - the ocean floor (abyssal zone). See the map.
Seas... In the basin of the Atlantic Ocean there are numerous seas, which are divided into: the internal ones - the Baltic, Azov, Black, Marmara and Mediterranean (in the latter, in turn, the seas are distinguished: Adriatic, Alboran, Balearic, Ionian, Cypriot, Ligurian, Tyrrhenian, Aegean) ; inter-island - the Irish and inland seas of the west coast of Scotland; marginal - Labrador, Severnoye, Sargassovo, Caribbean, Scotia (Scotia), Weddell, Lazareva, western part of Riiser-Larsen (see separate articles on the seas). The largest bays of the ocean: Biscay, Bristol, Guinea, Mexican, Maine, Saint Lawrence.
Islands... Unlike other oceans, the Atlantic Ocean has few seamounts, guyots and coral reefs, and there are no coastal reefs. The total area of the islands of the Atlantic Ocean is about 1070 thousand km 2. The main groups of islands are located on the outskirts of the continents: British (Great Britain, Ireland, etc.) - the largest in area, Greater Antilles (Cuba, Haiti, Jamaica, etc.), Newfoundland, Iceland, the Tierra del Fuego archipelago (Tierra del Fuego, Oste, Navarino ), Marajo, Sicily, Sardinia, Lesser Antilles, Falkland (Malvinas), Bahamas, etc. In the open ocean there are small islands: Azores, Sao Paulo, Ascension, Tristan da Cunha, Bouvet (on the Mid-Atlantic ridge) and dr.
The shores... The coastline in the North Atlantic Ocean is heavily indented (see also the article Shore), almost all large inland seas and bays are located here, in the South Atlantic, the shores are weakly indented. The shores of Greenland, Iceland and the coast of Norway are predominantly of tectonic-glacial dissection of the fjord and fiard types. Further south, in Belgium, they give way to sandy shoals. The Flanders coast is mainly of artificial origin (coastal dams, polders, canals, etc.). The shores of the island of Great Britain and the island of Ireland are abrasion-coiled, high limestone cliffs alternate with sandy beaches and muddy drylands. On the Cherbourg peninsula there are rocky shores, sandy and gravel beaches. The northern coast of the Iberian Peninsula is composed of rock formations, to the south, off the coast of Portugal, sandy beaches prevail, often fencing off lagoons. Sandy beaches also border the shores of Western Sahara and Mauritania. To the south of Cape Zelyoniy there are leveled abrasion-bay shores with mangrove thickets. The western section of Côte d'Ivoire has an accumulative
coast with rocky capes. To the southeast, to the vast delta of the Niger River, there is an accumulative bank with a significant number of spits and lagoons. In southwestern Africa, there are accumulative, less often abrasion-bay shores with extensive sandy beaches. The shores of southern Africa of the abrasion-bay type are composed of hard crystalline rocks. The shores of Arctic Canada are abrasive, with high cliffs, glacial deposits and limestones. In eastern Canada and northern St Lawrence Bay, there are intensely eroded limestone and sandstone cliffs. In the west and south of the Gulf of St. Lawrence, there are wide beaches. On the shores of the Canadian provinces of Nova Scotia, Quebec, Newfoundland - outcrops of hard crystalline rocks. From about 40 ° north latitude to Cape Canaveral in the United States (Florida) - an alternation of leveled accumulative and abrasion types of shores, composed of loose rocks. The Gulf Coast is low-lying, fringed by Florida mangroves, Texas sand barriers, and Louisiana delta shores. On the Yucatan Peninsula - cemented beach sediments, to the west of the peninsula - an alluvial-marine plain with coastal ramparts. On the Caribbean coast, abrasion and accumulation areas alternate with mangrove swamps, coastal barriers and sandy beaches. To the south of 10 ° north latitude, accumulative banks are widespread, composed of material carried out from the mouth of the Amazon River and other rivers. In the northeast of Brazil, there is a sandy coast with mangrove thickets, interrupted by river estuaries. From Cape Kalkanyar to 30 ° South latitude there is a high abrasion-type coastline. To the south (off the coast of Uruguay) there is an abrasion-type coast, composed of clays, loesses, and sand and gravel deposits. In Patagonia, the shores are represented by high (up to 200 m) cliffs with loose sediments. The shores of Antarctica are 90% composed of ice and belong to the ice and thermal abrasion type.
Bottom relief... At the bottom of the Atlantic Ocean, the following large geomorphological provinces are distinguished: the underwater margin of the continents (shelf and continental slope), the ocean floor (deep-sea basins, abyssal plains, zones of abyssal hills, uplifts, mountains, deep-sea trenches), mid-ocean ridges.
The boundary of the continental shelf (shelf) of the Atlantic Ocean runs on average at depths of 100-200 m, its position can vary from 40-70 m (in the area of Cape Hatteras and the Florida Peninsula) to 300-350 m (Weddell Cape). The shelf width ranges from 15-30 km (northeastern Brazil, Iberian Peninsula) to several hundred km (North Sea, Gulf of Mexico, Bank of Newfoundland). In high latitudes, the relief of the shelf is complex and bears traces of glacial impact. Numerous uplifts (banks) are separated by longitudinal and transverse valleys or trenches. Off the coast of Antarctica, ice shelves are located on the shelf. At low latitudes, the shelf surface is more leveled, especially in the zones of terrigenous material removal by rivers. It is crossed by transverse valleys, often turning into canyons of the continental slope.
The slope of the continental slope of the ocean averages 1-2 ° and varies from 1 ° (areas of Gibraltar, Shetland Islands, part of the African coast, etc.) to 15-20 ° off the coast of France and Bahamas... The height of the continental slope varies from 0.9-1.7 km near the Shetland Islands and Ireland to 7-8 km in the Bahamas and the Puerto Rico trench. The active margins are characterized by high seismicity. The surface of the slope is in places dissected by steps, scarps and terraces of tectonic and accumulative origin and longitudinal canyons. At the foot of the continental slope there are often gentle hills up to 300 m high and shallow underwater valleys.
In the middle part of the floor of the Atlantic Ocean is the largest mountain system of the Mid-Atlantic Ridge. It stretches from Iceland to Bouvet Island for 18,000 km. The width of the ridge is from several hundred to 1000 km. The ridge runs close to the midline of the ocean, dividing it into eastern and western parts. On both sides of the ridge, there are deep-water basins separated by bottom uplifts. In the western part of the Atlantic Ocean, the following basins are distinguished from north to south: Labrador (with depths of 3000-4000 m); Newfoundland (4200-5000 m); The North American Basin (5000-7000 m), which includes the Som, Hatteras and Nares abyssal plains; Guiana (4500-5000 m) with the plains of Demerara and Ceara; Brazilian Basin (5000-5500 m) with the Abyssal Plain of Pernambuco; Argentinian (5000-6000 m). In the eastern part of the Atlantic Ocean there are basins: Western European (up to 5000 m), Iberian (5200-5800 m), Canary (over 6000 m), Cape Verde (up to 6000 m), Sierra Leone (about 5000 m), Guinean (over 5000 m) ), Angolan (up to 6000 m), Cape (over 5000 m) with the abyssal plains of the same name. In the south is the African-Antarctic Basin with the Weddell Abyssal Plain. The bottom of the deep-water basins at the foot of the Mid-Atlantic Ridge is occupied by a zone of abyssal hills. The hollows are separated by the uplifts of Bermuda, Rio Grande, Rockall, Sierra Leone, and others, the Kitovy, Newfoundland ridges, and others.
Seamounts (isolated conical elevations with a height of 1000 m and more) on the floor of the Atlantic Ocean are concentrated mainly in the zone of the Mid-Atlantic Ridge. In the deep-water part, large groups of seamounts are found north of Bermuda, in the Gibraltar sector, at the northeastern bulge of South America, in the Gulf of Guinea and west of South Africa.
Deep-sea trenches Puerto Rico, Cayman (7090 m), South Sandwich trough (8264 m) are located near the island arcs. The Romansh Trench (7856 m) is a large fault. The steepness of the slopes of the deep-water trenches is from 11 ° to 20 °. The bottom of the gutters is flat, leveled by accumulation processes.
Geological structure. The Atlantic Ocean emerged as a result of the collapse of the late Paleozoic supercontinent Pangea during the Jurassic time. It is characterized by a sharp predominance of passive outskirts. The Atlantic Ocean is bordered by adjacent continents along transform faults south of Newfoundland Island, along the northern coast of the Gulf of Guinea, along the Falklands Submarine Plateau and the Agulhas Plateau in the southern part of the ocean. Active margins are observed in some areas (in the area of the Lesser Antilles arc and the arc of the South Sandwich Islands), where subsidence occurs with subduction (subduction) of the Atlantic Ocean crust. The limited extent of the Gibraltar subduction zone has been identified in the Gulf of Cadiz.
In the Mid-Atlantic Ridge, the bottom is spreading (spreading) and the formation of the oceanic crust at a rate of up to 2 cm per year. High seismic and volcanic activity is characteristic. To the north of the Mid-Atlantic Ridge, paleospreading ridges branch off into the Labrador Sea and the Bay of Biscay. In the axial part of the ridge, there is a pronounced rift valley, which is absent in the extreme south and in most of the Reykjanes ridge. Within its limits are volcanic uplifts, frozen lava lakes, basaltic lava flows in the form of pipes (pillubasalts). In the Central Atlantic, fields of metalliferous fluids have been discovered, many of which form hydrothermal edifices at the outlet (composed of sulfides, sulfates, and metal oxides); metal-bearing sediments have been established. At the foot of the slopes of the valley there are taluses and landslides, consisting of boulders and rubble of rocks of the oceanic crust (basalts, gabbros, peridotites). The age of the crust within the Oligocene ridge is modern. The Mid-Atlantic Ridge separates the zones of the western and eastern abyssal plains, where the oceanic basement is overlain by a sedimentary cover, the thickness of which increases towards the continental foothills to 10-13 km due to the appearance of more ancient horizons in the section and the influx of clastic material from the land. In the same direction, the age of the oceanic crust increases, reaching the Early Cretaceous (north of Florida in the Middle Jurassic). The abyssal plains are practically aseismic. The Mid-Atlantic Ridge is crossed by numerous transform faults extending to the adjacent abyssal plains. The thickening of such faults is observed in the equatorial zone (up to 12 by 1700 km). The largest transform faults (Vima, Sao Paulo, Romansh, etc.) are accompanied by deep incisions (grooves) on the ocean floor. They reveal the entire section of the oceanic crust and partly of the upper mantle; there are widespread protrusions (cold intrusions) of serpentinized peridotites, forming ridges elongated along the strike of the faults. Many transform faults are transoceanic, or main (demarcation) faults. The Atlantic Ocean contains the so-called intraplate uplifts, represented by submarine plateaus, aseismic ridges and islands. They have a thick oceanic crust and are mainly of volcanic origin. Many of them were formed as a result of the action of mantle jets (plumes); some arose at the intersection of the spreading ridge by large transform faults. Volcanic uplifts include: Iceland Island, Bouvet Island, Madeira Island, Canary Islands, Cape Verde, Azores, pair of Sierra and Sierra Leone uplifts, Rio Grande and Whale Ridge, Bermuda Uplift, Cameroon group of volcanoes, etc. In the Atlantic Ocean there are intraplate uplifts of non-volcanic nature, including the Rockall underwater plateau, separated from the British Isles by the trough of the same name. The plateau is a microcontinent that split off from Greenland in the Paleocene. Another microcontinent also split off from Greenland is the Hebrides Massif in northern Scotland. Submarine marginal plateaus off the coast of Newfoundland (Great Newfoundland, Flemish Cap) and off the coast of Portugal (Iberian) were cut off from the continents as a result of rifting in the late Jurassic - early Cretaceous.
The Atlantic Ocean is divided by transoceanic transform faults into segments with different opening times. From north to south, the Labrador-British, Newfoundland-Iberian, Central, Equatorial, Southern and Antarctic segments are distinguished. The opening of the Atlantic began in the early Jurassic (about 200 million years ago) from the Central Segment. In the Triassic - Early Jurassic, the spreading of the ocean floor was preceded by continental rifting, traces of which are recorded in the form of semi-grabens (see Graben) filled with clastic deposits on the American and North African margins of the ocean. In the late Jurassic - early Cretaceous, the Antarctic segment began to open. In the Early Cretaceous, spreading was experienced by the Southern Segment in the South Atlantic and the Newfoundland-Iberian Segment in the North Atlantic. Opening of the Labrador-British segment began at the end of the Early Cretaceous. At the end of the Late Cretaceous, the Labrador Basin Sea arose here as a result of spreading on the side axis, which continued until the Late Eocene. The North and South Atlantic united in the middle Cretaceous - Eocene during the formation of the Equatorial segment.
Bottom sediments ... The thickness of the strata of modern bottom sediments ranges from several meters in the zone of the ridge of the Mid-Atlantic Ridge to 5-10 km in the zones of transverse faults (for example, in the Romanche trench) and at the foot of the continental slope. In deep-water basins, their thickness is from several tens to 1000 m. Over 67% of the ocean floor area (from Iceland in the north to 57-58 ° south latitude) is covered with calcareous deposits formed by the remains of shells of planktonic organisms (mainly foraminifera, coccolithophorids). Their composition varies from coarse sands (at depths of up to 200 m) to silts. At depths of more than 4500-4700 m, lime mud is replaced by polygenic and siliceous planktonic sediments. The former occupy about 28.5% of the ocean floor area, lining the bottoms of the basins, and are represented by deep-sea red oceanic clay (deep-sea clayey silts). These sediments contain a significant amount of manganese (0.2-5%) and iron (5-10%) and a very small amount of carbonate material and silicon (up to 10%). Siliceous planktonic sediments occupy about 6.7% of the ocean floor, of which diatom oozes (formed by the skeletons of diatoms) are the most widespread. They are common off the coast of Antarctica and on the shelf of Southwest Africa. Radiolarian oozes (formed by the skeletons of radiolarians) are found mainly in the Angola Basin. Terrigenous sediments of various compositions (gravel-pebble, sandy, clayey, etc.) are developed along the coast of the ocean, on the shelf and partly on the continental slopes. The composition and thickness of terrigenous sediments are determined by the bottom topography, the activity of the influx of solid material from the land and the mechanism of their transfer. Glacial precipitation carried by icebergs is widespread along the coast of Antarctica, Greenland, Newfoundland, and the Labrador Peninsula; composed of poorly sorted detrital material with the inclusion of boulders, mostly in the south of the Atlantic Ocean. In the equatorial part, sediments (from coarse sand to silt) formed from pteropod shells are often found. Coral sediments (coral breccias, pebbles, sands and silts) are found in the Gulf of Mexico, the Caribbean and off the northeastern coast of Brazil; their maximum depth is 3500 meters. Volcanic sediments are developed near volcanic islands (Iceland, Azores, Canary, Cape Verde, etc.) and are represented by fragments of volcanic rocks, slag, pumice, volcanic ash. Modern chemogenic sediments are found in the Big Bahamas Bank, in the Florida-Bahamas, Antilles regions (chemogenic and chemogenic-biogenic carbonates). Ferromanganese nodules are found in the depressions of the North American, Brazilian, and Cape Verde; their composition in the Atlantic Ocean: manganese (12.0-21.5%), iron (9.1-25.9%), titanium (up to 2.5%), nickel, cobalt and copper (tenths of a percent). Phosphorite nodules appear at depths of 200-400 m off the east coast of the United States and the northwest coast of Africa. Phosphorites are distributed along the eastern coast of the Atlantic Ocean - from the Iberian Peninsula to Cape Agulhas.
Climate... Due to the large extent of the Atlantic Ocean, its waters are located in almost all natural climatic zones - from the subarctic in the north to the Antarctic in the south. From the north and south, the ocean is wide open to the impact of Arctic and Antarctic waters and ice. The lowest air temperature is observed in the polar regions. Over the coast of Greenland, temperatures can drop to -50 ° C, and in the southern Weddell Sea, temperatures of -32.3 ° C have been recorded. In the equatorial region, the air temperature is 24-29 ° C. The pressure field over the ocean is characterized by a successive change of stable large baric formations. Above the ice domes of Greenland and Antarctica there are anticyclones, in the temperate latitudes of the Northern and Southern Hemispheres (40-60 °) - cyclones, in lower latitudes - anticyclones, separated by a zone of low pressure at the equator. This baric structure supports steady eastward winds (trade winds) in tropical and equatorial latitudes, and strong westerly winds in temperate latitudes, which have been called "roaring forties" by seafarers. Strong winds typical for the Bay of Biscay. In the equatorial region, the interaction of the northern and southern baric systems leads to frequent tropical cyclones (tropical hurricanes), the greatest activity of which is observed from July to November. The horizontal dimensions of tropical cyclones are up to several hundred kilometers. The wind speed in them is 30-100 m / s. They move, as a rule, from east to west at a speed of 15-20 km / h and reach their greatest strength over the Caribbean Sea and the Gulf of Mexico. In areas of low pressure in temperate and equatorial latitudes, precipitation often falls and strong clouds are observed. Thus, over 2000 mm of precipitation falls on the equator per year, in temperate latitudes - 1000-1500 mm. In areas of high pressure (subtropics and tropics), the amount of precipitation decreases to 500-250 mm per year, and in areas adjacent to the desert coast of Africa, and in the South Atlantic maximum - to 100 mm or less per year. In areas where warm and cold currents meet, fogs are frequent, for example, in the area of the Newfoundland Bank and in La Plata Bay.
Hydrological regime. Rivers and water balance. In the Atlantic Ocean basin, 19,860 km 3 of water is annually carried out by rivers, which is more than in any other ocean (about 45% of the total runoff into the World Ocean). The largest rivers (with an annual discharge of over 200 km): Amazon, Mississippi (flows into the Gulf of Mexico), St. Lawrence River, Congo, Niger, Danube (flows into the Black Sea), Parana, Orinoco, Uruguay, Magdalena (flows into the Caribbean Sea) ). However, the balance of fresh water in the Atlantic Ocean is negative: evaporation from its surface (100-125 thousand km 3 / year) significantly exceeds atmospheric precipitation (74-93 thousand km 3 / year), river and ground runoff (21 thousand km 3 / year) and melting of ice and icebergs in the Arctic and Antarctic (about 3 thousand km 3 / year). The water deficit is compensated by the influx of water, mainly from the Pacific Ocean, 3470 thousand km 3 / year flows through the Drake Passage with the flow of the Western Winds, and only 210 thousand km 3 / year leave the Atlantic Ocean to the Pacific Ocean. 260 thousand km 3 / year flows from the Arctic Ocean through numerous straits into the Atlantic Ocean, and 225 thousand km 3 / year of Atlantic waters flows back into the Arctic Ocean. The water balance with the Indian Ocean is negative, 4976 thousand km 3 / year are carried out into the Indian Ocean with the course of the Western Winds, and only 1692 thousand km 3 / year comes back with the Coastal Antarctic Current, deep and bottom waters.
Temperature regime... The average temperature of ocean waters as a whole is 4.04 ° С, and of surface waters 15.45 ° С. The distribution of water temperature on the surface is asymmetric relative to the equator. The strong influence of Antarctic waters leads to the fact that the surface waters of the Southern Hemisphere are almost 6 ° C colder than the North, the warmest waters of the open ocean (thermal equator) are located between 5 and 10 ° N latitude, that is, they are shifted north of the geographic equator. The peculiarities of large-scale water circulation lead to the fact that the water temperature at the surface near the western coast of the ocean is approximately 5 ° C higher than that of the eastern one. The most warm temperature water (28-29 ° С) on the surface in the Caribbean Sea and the Gulf of Mexico in August, the lowest - off the coast of Greenland, Baffin Island, Labrador Peninsula and Antarctica, south of 60 °, where even in summer the water temperature does not rise above 0 ° WITH. The water temperature in the layer of the main thermocline (600-900 m) is about 8-9 ° C, deeper, in intermediate waters, drops on average to 5.5 ° C (1.5-2 ° C in Antarctic intermediate waters). In deep waters, the average water temperature is 2.3 ° C, in bottom waters - 1.6 ° C. At the very bottom, the water temperature rises slightly due to the geothermal heat flux.
Salinity... The waters of the Atlantic Ocean contain about 1.1 · 10 16 tons of salts. The average salinity of the waters of the entire ocean is 34.6 ‰, surface waters 35.3 ‰. The highest salinity (over 37.5 ‰) is observed on the surface in subtropical regions, where the evaporation of water from the surface exceeds its input with atmospheric precipitation, the lowest (6-20 ‰) in the estuaries of large rivers flowing into the ocean. From subtropics to high latitudes, salinity on the surface decreases to 32-33 ‰ under the influence of precipitation, ice, river and surface runoff. In temperate and tropical regions, the maximum salinity values are on the surface, an intermediate salinity minimum is observed at depths of 600-800 m. The waters of the North Atlantic Ocean are characterized by a deep salinity maximum (more than 34.9 ‰), which is formed by highly saline Mediterranean waters. The deep waters of the Atlantic Ocean have a salinity of 34.7-35.1 ‰ and a temperature of 2-4 ° C, the bottom, occupying the deepest depressions of the ocean, 34.7-34.8 ‰ and 1.6 ° C, respectively.
Density... The density of water depends on temperature and salinity, and for the Atlantic Ocean, temperature is more important in the formation of the field of water density. The waters with the lowest density are located in the equatorial and tropical zones with high water temperatures and a strong influence of the runoff of such rivers as the Amazon, Niger, Congo, etc. (1021.0-1022.5 kg / m 3). In the southern part of the ocean, the density of surface waters increases to 1025.0-1027.7 kg / m 3, in the northern part - up to 1027.0-1027.8 kg / m 3. The density of the deep waters of the Atlantic Ocean is 1027.8-1027.9 kg / m 3.
Ice regime... In the North Atlantic Ocean, first-year ice forms mainly in the inland seas of temperate latitudes, perennial ice is carried out from the Arctic Ocean. The boundary of the distribution of ice cover in the North Atlantic Ocean changes significantly, in winter period pack ice can reach 50-55 ° north latitude in different years. There is no ice in summer. Antarctic border perennial ice in winter it passes at a distance of 1600-1800 km from the coast (approximately 55 ° south latitude), in summer (in February - March) ice occurs only in the coastal strip of Antarctica and in the Weddell Sea. The main suppliers of icebergs are the ice sheets and ice shelves of Greenland and Antarctica. The total mass of icebergs coming from Antarctic glaciers is estimated at 1.6 · 10 12 tons per year, the main source of which is the Filchner Ice Shelf in the Weddell Sea. Icebergs with a total mass of 0.2-0.3 x 10 12 tons per year come from the glaciers of the Arctic into the Atlantic Ocean, mainly from the Jacobshavn Glacier (in the area of Disko Island off the western coast of Greenland). The average lifespan of Arctic icebergs is about 4 years, Antarctic icebergs are slightly longer. The boundary of the distribution of icebergs in the northern part of the ocean is 40 ° north latitude, but in some cases they were observed up to 31 ° north latitude. In the southern part, the border runs at 40 ° S, in the central part of the ocean and at 35 ° S on the western and eastern periphery.
Currents... The water circulation of the Atlantic Ocean is subdivided into 8 quasi-stationary oceanic gyres located almost symmetrically relative to the equator. Tropical anticyclonic, tropical cyclonic, subtropical anticyclonic, subpolar cyclonic oceanic gyres are located in the Northern and Southern Hemispheres from low to high latitudes. Their boundaries, as a rule, are the main oceanic currents. The warm current of the Gulf Stream begins at the Florida Peninsula. Taking in the waters of the warm Antilles Current and the Florida Current, the Gulf Stream is directed to the northeast and at high latitudes is divided into several branches; the most significant of them are the Irminger Current, which carries warm waters to the Davis Strait, the North Atlantic Current, and the Norwegian Current, which flows into the Norwegian Sea and further to the northeast, along the coast of the Scandinavian Peninsula. A cold Labrador Current emerges from the Davis Strait towards them, the waters of which can be traced off the coast of America to almost 30 ° north latitude. The cold East Greenland Current flows from the Danish Strait into the ocean. In the low latitudes of the Atlantic Ocean, warm North trade currents and South trade winds are directed from east to west, between them, at about 10 ° north latitude, from west to east there is an inter-trade countercurrent, which is active mainly in summer in the northern hemisphere. From the South trade winds, the Brazilian current is separated, which runs from the equator and up to 40 ° south latitude along the coast of America. The northern branch of the South Tradewinds forms the Guiana Current, which runs from south to northwest until it joins the waters of the North Tradewinds. Off the coast of Africa, from 20 ° north latitude to the equator, the warm Guinean Current passes; in summer, the Inter-trade countercurrent is connected to it. In the southern part, the Atlantic Ocean is crossed by the cold West Winds Current (Antarctic Circumpolar Current), which enters the Atlantic Ocean through the Drake Passage, descends to 40 ° S latitude and exits into the Indian Ocean south of Africa. It is separated from it by the Falkland Current, which runs along the coast of America almost to the mouth of the Parana River, and the Benguela Current, which runs along the coast of Africa almost to the equator. The cold Canary Current runs from north to south - from the shores of the Iberian Peninsula to the Cape Verde Islands, where it passes into the North Trade Winds.
Deep water circulation... The deep circulation and structure of the Atlantic Ocean waters are formed as a result of changes in their density during cooling of waters or in zones of mixing of waters of different origins, where the density increases as a result of mixing of waters with different salinity and temperature. Subsurface waters are formed in subtropical latitudes and occupy a layer with a depth of 100-150 m to 400-500 m, with a temperature of 10 to 22 ° C and a salinity of 34.8-36.0 ‰. Intermediate waters are formed in subpolar regions and are located at depths from 400-500 m to 1000-1500 m, with a temperature of 3 to 7 ° C and a salinity of 34.0-34.9 ‰. The circulation of subsurface and intermediate waters is generally anticyclonic in nature. Deep waters form in the high latitudes of the northern and southern parts of the ocean. The waters formed in the Antarctic region have the highest density and spread from south to north in the bottom layer, their temperature is from negative (in high southern latitudes) to 2.5 ° C, salinity is 34.64-34.89 ‰. Waters formed in high northern latitudes move from north to south in a layer from 1500 to 3500 m, the temperature of these waters is from 2.5 to 3 ° C, salinity is 34.71-34.99 ‰. In the 1970s, V.N. Stepanov and, later, V.S. The broker substantiated the scheme of planetary interoceanic transfer of energy and matter, called the "global conveyor" or "global thermohaline circulation of the World Ocean." According to this theory, relatively salty North Atlantic waters reach the coast of Antarctica, mix with supercooled shelf water and, passing through the Indian Ocean, end their journey in the North Pacific Ocean.
Tides and excitement... The tides in the Atlantic Ocean are predominantly semidiurnal. Tidal wave height: 0.2-0.6 m in the open ocean, a few centimeters in the Black Sea, 18 meters in the Bay of Fundy (northern Gulf of Maine in North America) - the highest in the world. The height of wind waves depends on the speed, time of exposure and acceleration of the wind; during severe storms it can reach 17-18 m. Rarely enough (once every 15-20 years), waves with a height of 22-26 m were observed.
Flora and fauna... Great extent of the Atlantic Ocean, diversity climatic conditions, a significant inflow of fresh water and large upwellings provide a variety of living conditions. In total, about 200 thousand species of plants and animals live in the ocean (of which there are about 15,000 species of fish, about 600 species of cephalopods, about 100 species of whales and pinnipeds). Life is very unevenly distributed in the ocean. There are three main types of zoning in the distribution of life in the ocean: latitudinal, or climatic, vertical and circumcontinental zoning. The density of life and its species diversity decrease with distance from the coast towards the open ocean and from the surface to deep waters. Species diversity also decreases from tropical latitudes to high ones.
Planktonic organisms (phytoplankton and zooplankton) are the basis of the food chain in the ocean, the bulk of them live in the upper zone of the ocean, where light penetrates. The greatest biomass of plankton is in high and temperate latitudes during spring-summer flowering (1-4 g / m 3). During the year, the biomass can change 10-100 times. The main types of phytoplankton are diatoms, zooplankton - copepods and euphausids (up to 90%), as well as bristle-mandibular, hydromedusa, comb jellies (in the north) and salps (in the south). At low latitudes, the plankton biomass varies from 0.001 g / m 3 in the centers of anticyclonic gyres to 0.3-0.5 g / m 3 in the Gulfs of Mexico and Guinea. Phytoplankton is represented mainly by coccolithins and peridineas, the latter can develop in coastal waters in huge numbers causing the catastrophic phenomenon of the "red tide". Zooplankton of low latitudes are represented by copepods, chaetomaxillary, hyperids, hydromedusae, siphonophores and other species. There are no clearly pronounced dominant species of zooplankton at low latitudes.
Benthos is represented by large algae (macrophytes), which mostly grow on the bottom of the shelf zone, to a depth of 100 m and cover about 2% of the total area of the ocean floor. The development of phytobenthos is observed in those places where there are suitable conditions - soils suitable for attachment to the bottom, the absence or moderate velocities of bottom currents, etc. In the high latitudes of the Atlantic Ocean, the main part of phytobenthos is made up of kelp and red algae. In the temperate zone of the North Atlantic Ocean, along the American and European coasts, there are brown algae (fucus and ascophyllum), kelp, desmarestia and red algae (furcellaria, anfeltia, etc.). Zostera is common on soft soils. The temperate and cold zones of the southern Atlantic Ocean are dominated by brown algae. In the tropical zone in the littoral zone, due to strong heating and intense insolation, vegetation on the ground is practically absent. A special place is occupied by the ecosystem of the Sargasso Sea, where floating macrophytes (mainly three types algae Sargassum) form clusters on the surface in the form of ribbons from 100 m to several kilometers long.
Most of the biomass of nekton (actively swimming animals - fish, cephalopods and mammals) is fish. The largest number of species (75%) lives in the shelf zone, with depth and distance from the coast, the number of species decreases. The cold and temperate zones are characterized by: fish - various types of cod, haddock, pollock, herring, flounder, catfish, conger eel, etc., herring and polar sharks; among mammals - pinnipeds (harp seal, hooded seal, etc.), various species of cetaceans (whales, sperm whales, killer whales, grinds, bottlenose, etc.).
There are great similarities between the faunas of the temperate and high latitudes of both hemispheres. At least 100 animal species are bipolar, that is, they are characteristic of both temperate and high belts. The tropical zone of the Atlantic Ocean is characterized by: fish - various sharks, flying fish, sailboats, various types of tuna and glowing anchovies; from animals - sea turtles, sperm whales, river dolphin inia; cephalopods are also numerous - various types of squid, octopus, etc.
The deep-sea fauna (zoobenthos) of the Atlantic Ocean is represented by sponges, corals, echinoderms, crustaceans, molluscs, and various worms.
Research history
There are three stages in the study of the Atlantic Ocean. The first is characterized by the establishment of the boundaries of the ocean and the discovery of its individual objects. In the 12-5 centuries BC, the Phoenicians, Carthaginians, Greeks and Romans left descriptions of sea voyages and the first sea maps. Their voyages reached the Iberian Peninsula, England and the mouth of the Elbe. In the 4th century BC, Piteas (Pytheas), while sailing in the North Atlantic, determined the coordinates of a number of points and described the tidal phenomena in the Atlantic Ocean. The Canary Islands are mentioned in the 1st century AD. In the 9-10th centuries, the Normans (Eirik Raudie and his son Leif Erikson) crossed the ocean, visited Iceland, Greenland, Newfoundland and explored the shores of North America up to 40 ° north latitude. In the era of the Great geographical discoveries(mid-15th - mid-17th century) seafarers (mainly Portuguese and Spaniards) mastered the way to India and China along the coast of Africa. The most outstanding voyages during this period were made by the Portuguese B. Dias (1487), the Genoese J. Columbus (1492-1504), the Englishman J. Cabot (1497) and the Portuguese Vasco da Gama (1498), who for the first time tried to measure the depths of the open parts of the ocean and speed of surface currents.
The first bathymetric map (depth map) of the Atlantic Ocean was compiled in Spain in 1529. In 1520 F. Magellan first passed from the Atlantic Ocean to the Pacific Ocean by the strait, later named after him. In the 16-17 centuries the Atlantic coast of North America was intensively explored (the British J. Davis, 1576-78, G. Hudson, 1610, W. Baffin, 1616, and other navigators whose names can be found on the map of the ocean). The Falkland Islands were discovered in 1591-92. The southern shores of the Atlantic Ocean (mainland Antarctica) were discovered and first described by the Russian Antarctic expedition of F. F. Bellingshausen and M. P. Lazarev in 1819-21. This completed the study of the boundaries of the ocean.
The second stage is characterized by the study of the physical properties of ocean waters, temperature, salinity, currents, etc. Russian I.F. Kruzenshtern (1803) and others. In the 19th century, the Atlantic Ocean became a testing ground for developing new methods of exploring depths, new technology and new approaches to organizing work. For the first time, bathometers, deep-sea thermometers, thermo-depth meters, deep-water trawls and dredges are used. Among the most significant can be noted the Russian expeditions on the ships "Rurik" and "Enterprise" under the leadership of O.E. Kotzebue (1815-18 and 1823-26); English - on "Erebus" and "Terror" under the direction of J. Ross (1840-43); American - on "Seiklab" and "Arctic" under the leadership of MF Mori (1856-57). Real comprehensive oceanographic studies of the ocean began with an expedition on board the British corvette Challenger, led by C.W. Thomson (1872-76). Significant expeditions that followed her were carried out on the vessels Gazelle (1874-76), Vityaz (1886-89), Valdivia (1898-1899), Gauss (1901-03). A great contribution (1885-1922) to the study of the Atlantic Ocean was made by Prince Albert I of Monaco, who organized and headed expeditionary research on the yachts Irendel, Princess Alice, Irendel II, Princess Alice II in the northern part of the ocean. In the same years, he organized the Oceanographic Museum in Monaco. In 1903, work began on the "standard" sections in the North Atlantic under the leadership of the International Council for the Study of the Sea (ICES) - the first international oceanographic scientific organization that existed before the 1st World War.
The most significant expeditions in the period between the world wars were carried out on the ships "Meteor", "Discovery II", "Atlantis". In 1931, the International Council of Scientific Unions (ICSU) was formed, which operates to the present day, organizing and coordinating ocean research.
After World War II, an echo sounder was widely used to study the ocean floor. This allowed us to get a real picture of the topography of the ocean floor. In the 1950s-70s, comprehensive geophysical and geological studies of the Atlantic Ocean were carried out and the features of the topography of its bottom and tectonics, the structure of the sedimentary stratum, were established. Many large forms of bottom topography have been identified (underwater ridges, mountains, trenches, fault zones, vast basins and uplifts), and geomorphological and tectonic maps have been compiled.
The third stage of ocean research is mainly aimed at studying its role in global processes of transfer of matter and energy, and its influence on climate formation. The complexity and wide range of research work required extensive international collaboration. The Scientific Committee for Oceanographic Research (SCOR), formed in 1957, the Intergovernmental Oceanographic Commission at UNESCO (IOC), operating since 1960, and other international organizations play an important role in the coordination and organization of international research. In 1957-58, great work within the framework of the first International Geophysical Year (IGY). Subsequently, large international projects are aimed not only at studying individual parts of the Atlantic Ocean (for example, EQUALANT I-III; 1962-1964; Polygon, 1970; CICAR, 1970-75; POLYMODE, 1977; TOGA, 1985-89), but also at its study as a part of the World Ocean (GEOSECS, 1973-74; WOCE, 1990-96, and others). During the implementation of these projects, the features of the circulation of waters of various scales, the distribution and composition of suspended matter, the role of the ocean in the global carbon cycle, and many other issues were studied. In the late 1980s, the unique ecosystems of the geothermal regions of the rift zone of the ocean were investigated by Soviet deep-sea vehicles "Mir". If at the beginning of the 1980s there were about 20 international ocean research projects, then by the 21st century there were more than 100. The largest programs: International Geosphere-Biosphere Program (since 1986, 77 countries participate), it includes projects “Interaction land - ocean in coastal zone ”(LOICZ),“ Global Fluxes of Matter in the Ocean ”(JGOFS),“ Dynamics of Global Oceanic Ecosystems ”(GLOBES),“ World Climate Research Program ”(since 1980, 50 countries participate) and many others. The Global Ocean Observing System (GOOS) is being developed.
Economic use
The Atlantic Ocean occupies the most important place in the world economy among other oceans of our planet. Human use of the Atlantic Ocean, like other seas and oceans, goes in several main directions: transport and communications, fishing, mining of mineral resources, energy, and recreation.
Transport... For 5 centuries, the Atlantic Ocean has played a leading role in maritime transport. With the opening of the Suez (1869) and Panama (1914) canals, short sea routes appeared between the Atlantic, Indian and Pacific oceans... The Atlantic Ocean accounts for about 3/5 of the world's shipping traffic; at the end of the 20th century, up to 3.5 billion tons of cargo was transported across its waters per year (according to the IOC). Oil, gas and oil products account for about 1/2 of the traffic volume, followed by general cargo, then iron ore, grain, coal, bauxite and alumina. The main direction of transportation is the North Atlantic, which runs between 35-40 ° north latitude and 55-60 ° north latitude. The main shipping routes connect the port cities of Europe, the USA (New York, Philadelphia) and Canada (Montreal). This direction is adjacent to the sea routes of the Norwegian, Northern and inland seas Europe (Baltic, Mediterranean and Black). Mainly raw materials (coal, ores, cotton, timber, etc.) and general cargo are transported. Other important directions of transportation - South Atlantic: Europe - Central (Panama, etc.) and South America (Rio de Janeiro, Buenos Aires); East Atlantic: Europe - southern Africa (Cape Town); West Atlantic: North America, South America - southern Africa. Before the reconstruction of the Suez Canal (1981), most of the oil tankers from the Indian Basin were forced to sail around Africa.
Passenger transportation has been an important place in the Atlantic Ocean since the 19th century, when mass emigration from the Old World to America began. The first steam-sailing vessel "Savannah" crossed the Atlantic Ocean in 28 days in 1818. At the beginning of the 19th century, the Blue Ribbon prize was established for passenger ships that would cross the ocean faster. This prize was awarded, for example, to such famous liners as "Lusitania" (4 days and 11 hours), "Normandy" (4 days and 3 hours), "Queen Mary" (4 days without 3 minutes). The last time the Blue Ribbon was awarded to the American liner United States was in 1952 (3 days and 10 hours). At the beginning of the 21st century, the duration of a passenger liner flight between London and New York was 5-6 days. The maximum passenger traffic across the Atlantic Ocean occurred in 1956-57, when more than 1 million people were transported a year, in 1958 the volume of passenger traffic by air was equal to sea transport, and then an increasing number of passengers prefer air transport (the record flight time of a supersonic liner "Concorde" on the route New York - London - 2 hours 54 minutes). The first non-stop flight across the Atlantic Ocean was made on 14-15 June 1919 by the English pilots J. Alcock and A. W. Brown (Newfoundland Island - the island of Ireland), the first non-stop flight across the Atlantic Ocean alone (from continent to continent) 20-21 May 1927 - American pilot C. Lindbergh (New York - Paris). At the beginning of the 21st century, almost all the flow of passengers across the Atlantic Ocean is served by aviation.
Connection... In 1858, when there was no radio communication between continents, the first telegraph cable was laid across the Atlantic Ocean. By the end of the 19th century, 14 telegraph cables connected Europe with America and 1 with Cuba. In 1956, the first telephone cable was laid between the continents; by the mid-1990s, over 10 telephone lines were operating on the ocean floor. In 1988, the first transatlantic fiber-optic communication line was laid; in 2001, 8 lines were in operation.
Fishing... The Atlantic Ocean is considered the most productive ocean and its biological resources are most intensively exploited by humans. In the Atlantic Ocean, fishing and seafood production account for 40-45% of the total world catch (an area of about 25% of the World Ocean). Most of the catch (up to 70%) is made up of herring fish (herring, sardines, etc.), cod fish (cod, haddock, hake, whiting, pollock, navaga, etc.), flounder, halibut, sea bass... The catch of molluscs (oysters, mussels, squid, etc.) and crustaceans (lobsters, crabs) is about 8%. According to FAO estimates, the annual catch of fish products in the Atlantic Ocean is 85-90 million tons, but for most of the fishing areas of the Atlantic, fish catch reached its maximum in the mid-1990s, and its increase is undesirable. The traditional and most productive fishing area is the northeastern part of the Atlantic Ocean, including the North and Baltic Seas (mainly herring, cod, flounder, sprats, mackerel). In the northwestern region of the ocean, on the Newfoundland banks, cod, herring, flounder, squid, etc. have been caught for many centuries. In the central part of the Atlantic Ocean, there is a catch of sardine, horse mackerel, mackerel, tuna, etc. -Falkland Shelf, fishing for both warm-water species (tuna, marlins, swordfish, sardines, etc.) and cold-water species (blue whiting, hake, notothenia, toothfish, etc.). Sardines, anchovy and hake are caught off the coast of western and southwestern Africa. In the Antarctic region of the ocean, planktonic crustaceans (krill), marine mammals are of commercial importance, from fish - notothenia, toothfish, silverfish, etc. For decades, it has sharply decreased due to the depletion of biological resources and thanks to environmental protection measures, including intergovernmental agreements on limiting their production.
Mineral resources... The mineral wealth of the ocean floor is being exploited more and more actively. Oil and combustible gas deposits have been studied more fully, the first mention of their exploitation in the Atlantic Ocean basin dates back to 1917, when oil production began on an industrial scale in the eastern part of the Maracaibo lagoon (Venezuela). Largest offshore production centers: Gulf of Venezuela, Maracaibo Lagoon (Maracaibo oil and gas basin), Gulf of Mexico (Gulf of Mexico oil and gas basin), Gulf of Paria (Orinoco oil and gas basin), Brazilian shelf (Sergipe-Alagoas oil and gas basin), Gulf of Guinea (Gulf of Guinea oil and gas basin) ), The North Sea (the North Sea is an oil and gas region), etc. Placer deposits of heavy minerals are widespread along many coasts. The largest development of placer deposits of ilmenite, monocyte, zircon, rutile is carried out off the coast of Florida. Such deposits are located in the Gulf of Mexico, off the east coast of the United States, as well as Brazil, Uruguay, Argentina and the Falkland Islands. Offshore diamond deposits are being developed on the shelf of southwestern Africa. Gold-bearing placers were found off the coast of Nova Scotia at depths of 25-45 m. One of the world's largest iron ore deposits, Wabana (in Conception Bay off the coast of Newfoundland), has been explored in the Atlantic Ocean; iron ore is also mined off the coast of Finland, Norway and France. In the coastal waters of Great Britain and Canada, coal deposits are being developed, it is mined in mines located on land, the horizontal workings of which go under the seabed. Large sulfur deposits are being developed on the shelf of the Gulf of Mexico. IN coastal zone the ocean mines sand for construction and the production of glass, gravel. Phosphorite-bearing sediments have been explored on the shelf of the east coast of the United States and the west coast of Africa, but their development is not yet profitable. The total mass of phosphorites on the continental shelf is estimated at 300 billion tons. At the bottom of the North American Basin and on the Blake Plate, large fields of ferromanganese nodules have been found, their total reserves in the Atlantic Ocean are estimated at 45 billion tons.
Recreational resources... Since the second half of the 20th century, the use of the recreational resources of the ocean has been of great importance for the economies of coastal countries. Old resorts are developing and new ones are being built. Since the 1970s, ocean liners designed only for cruises have been laid, they are distinguished by their large size (displacement of 70 thousand tons or more), an increased level of comfort and relative slowness. The main routes of the Atlantic Ocean cruise ships are the Mediterranean and the Caribbean and the Gulf of Mexico. From the late 20th - early 21st centuries, scientific tourism and extreme cruise routes have been developing, mainly in the high latitudes of the Northern and Southern Hemispheres. In addition to the Mediterranean and Black Sea basins, the main resort centers are located in the Canary Islands, Azores, Bermuda, the Caribbean Sea and the Gulf of Mexico.
Energy... The energy of the tides of the Atlantic Ocean is estimated at about 250 million kWh. In the Middle Ages, tidal wave mills and sawmills were built in England and France. A tidal power plant operates at the mouth of the Rance River (France). The use of hydrothermal energy of the ocean (the difference in temperature in surface and deep waters) is also considered promising; a hydrothermal station operates on the coast of Cote d'Ivoire.
Port cities... Most of the world's major ports are located on the shores of the Atlantic Ocean: in Western Europe - Rotterdam, Marseille, Antwerp, London, Liverpool, Genoa, Le Havre, Hamburg, Augusta, Southampton, Wilhelmshaven, Trieste, Dunkirk, Bremen, Venice, Gothenburg, Amsterdam, Naples, Nantes Saint Nazaire, Copenhagen; in North America - New York, Houston, Philadelphia, Baltimore, Norfolk-Newport, Montreal, Boston, New Orleans; in South America- Maracaibo, Rio de Janeiro, Santos, Buenos Aires; in Africa - Dakar, Abi-jan, Cape Town. Russian port cities do not have direct access to the Atlantic Ocean and are located on the shores of the inland seas belonging to its basin: St. Petersburg, Kaliningrad, Baltiysk (Baltic Sea), Novorossiysk, Tuapse (Black Sea).
Lit .: Atlantic Ocean. M., 1977; Safyanov G. A. Coastal zone of the ocean in the XX century. M., 1978; Terms. Concepts, reference tables / Edited by S.G. Gorshkov. M., 1980; Atlantic Ocean. L., 1984; Biological resources Atlantic Ocean / Otv. editor D. E. Gershanovich. M., 1986; Broeker W. S. The great ocean conveyor // Oceanograpy. 1991. Vol. 4. No. 2; Pushcharovsky Yu. M. Atlantic tectonics with elements of nonlinear geodynamics. M., 1994; World ocean atlas 2001: In 6 vol. Silver Spring, 2002.
P. N. Makkaveev; AF Limonov (geological structure).
Atlantic Ocean- This is a "plot" of the water area of the World Ocean, which is bordered by Europe and Africa on the southern side, and South and North America on the western side. A huge mass of salt water, beautiful views, rich flora and fauna, hundreds of beautiful islands - this is all called the Atlantic Ocean.
Atlantic Ocean
Atlantic Ocean consider the second largest component of our planet (in the first place -). The coastline is clearly divided into water areas: seas, bays. Total area of the Atlantic Ocean, of the river basins that flow into it, is about 329.7 million km³ (this is 25% of the waters of the World Ocean).
For the first time the name of the ocean - Atlantis, is found in the works of Herodotus (5th century BC). Then the prototype modern name recorded in the writings of Pliny the Elder (1st century AD). It sounds like Oceanus Atlanticus, translated from the ancient Greek language - the Atlantic Ocean.
There are several versions of the etymology of the name of the ocean:
- in honor of the mythological titan Atlas (Atlas, which holds the entire firmament);
- from the name of the Atlas Mountains (they are located in the northern part of Africa);
- in honor of the mysterious and legendary continent Atlantis. Immediately I offer you an interesting video - the film "Battle of Civilizations - Find Atlantis"
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These are the versions and assumptions put forward about Atlantis and the mysterious Atlantean race.
As for the history of the formation of the ocean, scientists are sure that it arose due to the split of the disappeared supercontinent Pangea. It included 90% of the continental crust of our planet.
Atlantic Ocean on the world map
Every 600 million years, the continental blocks join together to split again over time. It was as a result of this process 160 tons years ago that Atlantic Ocean. Map currents shows that ocean waters move under the influence of cold and warm currents. 
These are all the main currents of the Atlantic Ocean.
Atlantic islands
The largest islands in the Atlantic Ocean are Ireland, Great Britain, Cuba, Puerto Rico, Haiti, Newfoundland. They are found in the northern sector of the ocean. Their total area is 700 t.km 2. Several groups of smaller islands are located in the eastern part of the ocean: Canary Islands,. On the west side are the Lesser Antilles groups. Their archipelago creates a unique arc of solid earth that surrounds the eastern sector of the waters.
It is impossible not to mention some of the most beautiful islands in the Atlantic -.
Atlantic Ocean water temperature
The waters of the Atlantic Ocean are colder than those of the Pacific (due to the large extent of the Mid-Atlantic Ridge). The average surface water temperature is +16.9, but it changes depending on the season. In February in the northern part of the water area and in August in the southern part, the most low temperature, and the highest is observed in other months.
Depth of the atlantic ocean
What is the depth of the Atlantic Ocean? The maximum depth of the Atlantic Ocean reaches 8742 m (recorded in the Puerto Rico Trench at 8742 m), and the average depth is 3736 m. The Puerto Rico Trench is located on the border of the ocean and the Caribbean Sea. Its length along the slopes of the Antilles ridge is 1200 km.
The area of the Atlantic Ocean is 91.66 million km². And a quarter of this territory falls on its seas. Here .
Atlantic Ocean: sharks and more
Underwater world of the atlantic ocean will amaze the imagination of any person with its wealth and variety. It is a unique ecosystem that brings together many species of plants and animals.
The flora of the Atlantic Ocean is represented mainly by bottom vegetation (phytobenthos): green, red, brown algae, kelp, flowering plants such as posidonia, filospadix.
A unique natural miracle, without exaggeration, can be called the Sargasso Sea, located in the Atlantic Ocean between 20 ° and 40 ° north latitude and 60 ° west longitude. On the surface of 70% of its water surface there are always brown algae - sargassum.
But most of the surface of the Atlantic Ocean is covered with phytoplankton (these are unicellular algae). Its mass, depending on the site, varies from 1 to 100 mg / m3.
Inhabitants of the atlantic ocean beautiful and mysterious, because many of their species are not fully understood. In cold and temperate waters lives a large number of different representatives of the underwater fauna. For example, pinnipeds, whales, perch, flounder, cod, herring, shrimp, crustaceans, molluscs. Many animals are bipolar, that is, they have adapted to a comfortable existence in both cold and temperate zones (turtles, crabs, jellyfish, fur seals, whales, seals, mussels).
A special class is made up of the inhabitants of the deep waters of the Atlantic Ocean. Corals, sponges, echinoderm fish species amaze and impress the human eye.
What are the sharks in the atlantic ocean can pay a visit to a gaping tourist? The number of species that live in the Atlantic exceeds a dozen. The most common are white, soup, blue, reef, giant, sand sharks. But, cases of attacks on people do not happen very often, and if they do happen, then more often because of the provocations of the people themselves.
The first officially recorded shark attack on a person happened on July 1, 1916, with Charles Van Sant on a New Jersey beach. But even then, the residents of the resort town perceived this incident as an accident. Such tragedies began to be registered only in 1935. But scientists - shark scientists Nichols, Murphy and Lewkas did not take the attacks lightly and began to strenuously search for their specific causes. As a result, they created their own theory of the "shark year". She argued that the attacks were motivated by the large migration of sharks. Since the beginning of 2013, according to the International Register of Shark Attacks, 55 cases of predator attacks on humans have been recorded in the world, 10 of them with fatal outcomes.
Bermuda Triangle
