Atlantic Ocean second in size only to the Pacific; its area is approximately 91.56 million km 2. It is distinguished from other oceans by the strong indentation of the coastline, which forms numerous seas and bays, especially in the northern part. In addition, the total area of river basins flowing into this ocean or its marginal seas is much larger than that of rivers flowing into any other ocean. Another difference of the Atlantic Ocean is a relatively small number of islands and a complex bottom topography, which, thanks to underwater ridges and uplifts, forms many separate basins.
NORTHERN ATLANTIC OCEAN
borders and coastlines.
The Atlantic Ocean is divided into northern and southern parts, the boundary between which is conventionally drawn along the equator. From an oceanographic point of view, however, the equatorial countercurrent, located at 5–8° N latitude, should be attributed to the southern part of the ocean. The northern boundary is usually drawn along the Arctic Circle. In some places this boundary is marked by underwater ridges.
In the Northern Hemisphere, the Atlantic Ocean has a heavily indented coastline. Its relatively narrow northern part is connected to the Arctic Ocean by three narrow straits. In the northeast, the Davis Strait, 360 km wide (at the latitude of the Arctic Circle), connects it with the Baffin Sea, which belongs to the Arctic Ocean. In the central part, between Greenland and Iceland, there is the Danish Strait, with a width of only 287 km at its narrowest point. Finally, in the northeast, between Iceland and Norway, there is the Norwegian Sea, approx. 1220 km. To the east, two water areas deeply protruding into the land separate from the Atlantic Ocean. The more northern of them begins with the North Sea, which to the east passes into the Baltic Sea with the Gulf of Bothnia and the Gulf of Finland. To the south there is a system of inland seas - the Mediterranean and the Black - total length OK. 4000 km. In the Strait of Gibraltar, which connects the ocean with the Mediterranean Sea, there are two oppositely directed currents one below the other. The lower position is occupied by the current from the Mediterranean Sea to the Atlantic Ocean, since the Mediterranean waters, due to more intensive evaporation from the surface, are characterized by greater salinity and, consequently, greater density.
In the tropical zone in the southwest of the North Atlantic are the Caribbean Sea and the Gulf of Mexico, connected to the ocean by the Strait of Florida. The coast of North America is indented by small bays (Pamlico, Barnegat, Chesapeake, Delaware and Long Island Sound); to the northwest are the Bays of Fundy and St. Lawrence, Belle Isle, Hudson Strait, and Hudson Bay.
Islands.
The largest islands are concentrated in the northern part of the ocean; these are the British Isles, Iceland, Newfoundland, Cuba, Haiti (Hispaniola) and Puerto Rico. On the eastern edge of the Atlantic Ocean there are several groups of small islands - Azores, Canaries, Cape Verde. There are similar groups in the western part of the ocean. Examples include the Bahamas, Florida Keys and Lesser Antilles. The archipelagos of the Greater and Lesser Antilles form an island arc surrounding the eastern part of the Caribbean Sea. AT pacific ocean such island arcs are characteristic of regions of deformations of the earth's crust. Deep-water trenches are located along the convex side of the arc.
Bottom relief.
The basin of the Atlantic Ocean is bordered by a shelf, the width of which varies. The shelf is cut by deep gorges - the so-called. submarine canyons. Their origin is still a matter of controversy. According to one theory, the canyons were cut by rivers when the ocean level was below present. Another theory links their formation with the activity of turbidity currents. It has been suggested that turbidity currents are the main agent responsible for the deposition of sediments on the ocean floor and that it is they that cut submarine canyons.
The bottom of the northern part of the Atlantic Ocean has a complex rugged relief, formed by a combination of underwater ridges, hills, basins and gorges. Most of the ocean floor, from a depth of about 60 m to several kilometers, is covered with thin, dark blue or bluish-green silt. A relatively small area is occupied by rocky outcrops and areas of gravel-pebble and sandy deposits, as well as deep-water red clays.
Telephone and telegraph cables have been laid on the shelf in the northern part of the Atlantic Ocean to connect North America with northwestern Europe. Here, the areas of industrial fishing, which are among the most productive in the world, are confined to the area of the North Atlantic shelf.
A rift zone extends along the axis of the Mid-Atlantic Ridge.
currents.
Surface currents in the North Atlantic Ocean move clockwise. The main elements of this large system are the warm current of the Gulf Stream directed to the north, as well as the North Atlantic, Canary and Northern Equatorial (Equatorial) currents. The Gulf Stream follows from the Strait of Florida and the island of Cuba in a northerly direction along the coast of the United States and at about 40 ° N. latitude. deviates to the northeast, changing its name to the North Atlantic Current. This current divides into two branches, one of which follows the northeast along the coast of Norway and further into the Arctic Ocean. It is because of it that the climate of Norway and all of northwestern Europe is much warmer than would be expected at latitudes corresponding to the region stretching from Nova Scotia to southern Greenland. The second branch turns south and further southwest along the coast of Africa, forming the cold Canary Current. This current moves to the southwest and joins the North Equatorial Current, which heads west towards the West Indies, where it merges with the Gulf Stream. To the north of the North Equatorial Current is an area of stagnant water, abundant in algae and known as the Sargasso Sea. Along the North Atlantic coast of North America, the cold Labrador Current passes from north to south, following from the Baffin Bay and the Labrador Sea and cooling the coast of New England.
SOUTHERN ATLANTIC OCEAN
borders and coastlines.
Some experts attribute to the Atlantic Ocean in the south the entire body of water up to the Antarctic ice sheet itself; others take for the southern boundary of the Atlantic an imaginary line connecting Cape Horn in South America with the Cape of Good Hope in Africa. The coastline in the southern part of the Atlantic Ocean is much less indented than in the northern part; there are also no inland seas along which the influence of the ocean could penetrate deep into the continents of Africa and South America. The only major bay on the African coast is Guinea. On the coast of South America, large bays are also few in number. The southernmost tip of this continent - Tierra del Fuego - has a rugged coastline, bordered by numerous small islands.
Islands.
There are no large islands in the South Atlantic Ocean, but there are separate isolated islands, such as Fernando de Noronha, Ascension, Sao Paulo, St. Helena, the Tristan da Cunha archipelago, and in the extreme south - Bouvet, South Georgia , South Sandwich, South Orkney, Falkland Islands.
Bottom relief.
In addition to the Mid-Atlantic Ridge, there are two main submarine mountain ranges in the South Atlantic. The whale range extends from the southwestern tip of Angola to about. Tristan da Cunha, where it joins the Mid-Atlantic. The Rio de Janeiro ridge stretches from the Tristan da Cunha Islands to the city of Rio de Janeiro and is a group of separate underwater hills.
currents.
The main current systems in the South Atlantic move counterclockwise. The South Tradewind current is directed to the west. At the protrusion of the east coast of Brazil, it divides into two branches: the northern one carries water along the northern coast of South America to the Caribbean, and the southern, warm Brazilian Current, moves south along the coast of Brazil and joins the West Winds Current, or Antarctic, which heads east and then to the northeast. Part of this cold current separates and carries its waters north along the African coast, forming the cold Benguela Current; the latter eventually joins the South Equatorial Current. The warm Guinea Current moves south along the coast of Northwest Africa to the Gulf of Guinea.
It is the edge of the world, beyond which there is no land. Therefore, for a long time, the name Western Ocean was also used in relation to it. The modern name arose around the 1st century AD in the writings of the scientist Pliny the Elder. Its origin is associated with ancient Greek myth about the titan Atlanta, who allegedly holds the entire firmament of the Earth. According to legends, this titan was located in the extreme west, that is, somewhere far away in the Atlantic Ocean.
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In terms of its total area of 91.66 million sq. km, the reservoir is second only to the Pacific Ocean. The deepest point of the Atlantic is the Puerto Rico Trench, located north of the island of the same name. Its depth reaches 8742 meters. About 16% of the ocean area is occupied by smaller water areas: seas, bays, straits.
Map "Sea of the Atlantic Ocean"
The following seas belong to the Atlantic Ocean basin:
Irish sea
It is located between the islands of Great Britain and Ireland. The largest ports on its coast are Dublin and Liverpool. The area of the sea is 100 thousand square meters. km, the average depth is 43 m, and the maximum depth is 175 m. In its water area there are two large islands, Man and Anglesey. In the north, the sea flows into the North Strait, and in the south into the Strait of St. George. The central point of the reservoir has coordinates 53°43′18″ s. sh. and 5°10′38″ W. d.
North Sea
On the map it can be found at the coordinates 55°51′47″ s. sh. and 3°20′23″ E. e. The sea washes Great Britain from the east and the Jutland and Scandinavian peninsulas from the west. The area of the reservoir is 750 thousand square meters. km, the greatest depth reaches 725 m, the average - 95 m. It plays a huge role in maritime trade, its ports, the largest of which are Rotterdam, Amsterdam, London and Hamburg, account for more than 20% of the world's cargo traffic. Also, a large amount of oil and gas is produced here, due to which Norway is almost the most prosperous state in the world.
norwegian sea
Geographers are still arguing about which ocean should include the Norwegian Sea (67°52′32″ N and 1°03′17″ E) - the Atlantic or the Arctic. It washes Norway from the western direction. Its area is 1.4 million square meters. km, and the depth averages 1600-1750 m, reaching a maximum of 3970 m. The conditional southern boundary of the reservoir runs along the Faroe Islands and the island of Iceland.
Baltic Sea
The center of this sea has coordinates 58°37′00″ s. sh. and 20°25′00″ E. e. The reservoir is connected to the North Sea by a system of five Danish straits. Its area is about 419 thousand square meters. km, and the average depth is 51 m. The deepest point of the bottom is at a depth of 470 m. The most important cities located on its coast are St. Petersburg, Helsinki, Tallinn, Riga, Stockholm, Copenhagen. The salinity of the sea is very low, and its decrease is observed in the northern direction. As a result, freshwater fish are found near the northern shores of the reservoir.
Mediterranean Sea
A huge reservoir with an area of about 2.5 million square meters. km and separating the South from the North. It also washes Western Asia (Turkey, Syria, Lebanon, Israel). The center of the sea can be found at 35° N. sh. 18° in. e. The depth of the reservoir reaches its maximum in the Central Basin (5121 m), and its average value is 1541 m. The coastline of the sea is strongly indented, as a result of which many inland seas are distinguished in its composition:
- Tyrrhenian;
- Balearic;
- Ionic;
- Ligurian;
- Adriatic;
- Aegean;
- Sea of Alboran.
Since ancient times, the Mediterranean Sea has played a painful role in the development of European civilization. It was on its shore that the first Greek policies were located. The Roman Empire became the first and so far the only state that managed to conquer the entire coast of the reservoir, and therefore for centuries it was called the Roman Sea.
In the west, the Mediterranean Sea flows into the Atlantic Ocean through the Strait of Gibraltar, and in the east it is connected to the Red Sea by the man-made Suez Canal. Through the Dardanelles, the Mediterranean Sea is connected to the Sea of Marmara and through it indirectly to the Black Sea.
Sea of Marmara
A very small reservoir with an area of only 11,472 square meters. km, which is intermediate between the Black and Mediterranean Seas. The Sea of Marmara (40°43′21″ N and 28°13′29″ E) washes the European part of Turkey from the east, and its Asian part from the west. The largest city on the coast is Istanbul, which used to be the capital of the Roman Empire and was called Constantinople. The maximum depth is 1355 m, and the average is 677 m.
Black Sea
It has an area of 422 thousand square meters. km and is the most important body of water for Russia, Ukraine and other coastal states. It is through him that most of the trading operations are carried out with outside world, and its coast is the most popular holiday destination. Repeatedly Russian empire faced in wars with the Ottomans for the right to pass through the Black Sea straits - the Bosporus and the Dardanelles, which connect the Black Sea (43 ° 17′49 ″ N and 34 ° 01′46 ″ E) with the Sea of Marmara and the Mediterranean.
The average depth of the reservoir is 1240 m, and the maximum reaches 2210 m. Interestingly, from about a depth of 150 meters, the water is highly saturated with hydrogen sulfide, which is why there is almost no life below this level, with the exception of some types of bacteria.
Sea of Azov
It is the shallowest sea on the planet, whose average depth does not exceed 7.5 m, and the maximum reaches only 13.5 m. Also, this reservoir with an area of 39 thousand square meters. km is also considered the most continental sea of the Earth, since in order to get from it to the ocean, it is necessary to cross 4 more seas: the Black, Marmara, Aegean, Mediterranean.
The Sea of Azov (46°05′06″ N and 36°31′44″ E) is an inland sea of two states - Russia and Ukraine. On its coast there are such large cities as Mariupol and Taganrog, and the largest river flowing into it is the Don. The reservoir is connected to the Black Sea through the Kerch Strait.
Riiser-Larsen Sea
One of the southernmost seas (68 ° S and 22 ° E) of the Atlantic Ocean, washing the coast (Queen Maud Land). Its area is more than 1.1 million square meters. km. From the east it borders on the Cosmonauts Sea, and from the west on the Lazarev Sea. The average depth of the reservoir is 3000 m, and the maximum is 5327 m. The sea is ice-bound for almost the entire year.
Sea of Lazarev
Neighbor of the Riiser-Larsen Sea, also bordering the Antarctic Queen Maud Land. The coordinates of its conditional center are 68 ° S. sh. and 5° in. The area of the reservoir is about 335 thousand square meters. km. The maximum depth reaches 4500 m, and the average is about 3000 m. The boundaries of the sea were determined only in 1962 by Soviet scientists. The sea is named after Mikhail Petrovich Lazarev, who took part in the discovery of the Antarctic continent.
Weddell Sea
Located between Coats Land and the Antarctic Peninsula. The area of the Weddell Sea (75° S, 45° W) is over 2.9 million square kilometers. km. The maximum depth of the reservoir reaches 6820 m, and the average is about 3000 m. Initially, the sea bore the name of the British monarch George IV, but in 1900 it was renamed in honor of James Weddell, who discovered this sea back in 1823. Interestingly, the reservoir is characterized by the highest transparency. If in distilled water a disk specially used for measuring transparency is visible at a distance of 80 m, then in the Weddell Sea the distance is reduced to only 79 m.
sea scotia
A reservoir with an area of 1.3 million square meters. km is located east of the Drake Passage and has coordinates 57 ° 30′ S. sh. and 40°00′ W e. Its boundaries are defined by three archipelagos:
- South Georgia;
- South Sandwich Islands;
- South Orkney Islands.
The average depth of the sea is 3096 m, which is the greatest result among all the seas of the Earth. The maximum depth is 6022 m.
caribbean sea
The reservoir washes the northern coast, Cuba, the Antilles and the east coast of Central America. The Caribbean Sea (14°31′32″ N 75°49′06″ W) covers an area of more than 2.7 million square kilometers. km. Its maximum depth is 7686 m, and the average is 2500 m.
During the years of colonialism, the region became one of the centers of maritime piracy. Today it is one of the most popular tourist destinations in the world.
Sargasso Sea
The Sargasso Sea (28°20′08″ N and 66°10′30″ W) does not wash the coast of any continent, its boundaries are determined by the sea currents: Canary, North Atlantic, North Trade Wind and Gulf Stream. The area bounded by them has a variable area from 6 to 7 million square meters. km. The greatest depth is 6995 m, and the average is 2100 m.
It is in the Sargasso Sea that the infamous Bermuda Triangle where planes and ships often disappear. Scientists attribute this to poor climatic conditions.
Sea Labrador
It is located between the Canadian peninsula of the same name, Greenland and the island of Newfileland. The coordinates of its center are 59°29′23″ s. sh. and 54°03′10″ W. The area of the reservoir is about 840 thousand square meters. km, and the maximum depth is 4316 m. The average depth is 1950 m. More than 65% of the sea surface is covered with ice in winter.
Irminger Sea
It is located between Iceland and Greenland, washing their southern shores. The area of the reservoir is 780 thousand square meters. km. The Irminger Sea (63°05′41″ N and 31°04′10″ W) has a maximum depth of 3124 m and an average depth of 1800 m.
celtic sea
It is located south of the Irish Sea and has coordinates 50 ° 30′08 ″ s. sh. and 7°54′52″ W. e. It received its modern name only in 1921, before that it was called “southwestern approaches to Great Britain”. Area - 350 thousand square meters. km. The maximum depth of the sea is 366 m, and the average depth is approximately 150 m.
Iroise Sea
A very small reservoir with an area of only 3550 square meters. km. Located off the coast of France, between the islands of Ouessant and Seine. Its coordinates are 48°13′00″ s. sh. and 4°48′00″ W. e. The maximum depth reaches 250 m, and the average does not exceed 80 m.
The area of the Atlantic Ocean with seas is 91.7 million km 2, which is about a quarter of the water area of the World Ocean. It has a unique configuration. It expands in the northern and southern parts, narrows in the equatorial to 2830 km and has a length from north to south of about 16,000 km. It contains about 322.7 million km 3 of water, which corresponds to 24% of the water volume of the World Ocean. About 1/3 of its area is occupied by the mid-ocean ridge. The average depth of the ocean is 3597 m, the maximum is 8742 m.
In the east, the ocean boundary runs from the Statland Peninsula (62°10¢ N 5°10¢ E) along the coast of Europe and Africa to Cape Agulhas and further along the 20° E meridian. to the intersection with Antarctica, in the south - along the coast of Antarctica, in the west - along the Drake Strait from Cape Sternek on the Antarctic Peninsula to Cape Horn in the Tierra del Fuego archipelago, along the coast of South and North America to the southern entrance cape of the Hudson Strait, in the north along a conditional line - the southern entrance cape of the Hudson Strait, Cape Ulsingham (Baffin Island), Cape Burnil (Greenland Island), Cape Gerpire (Iceland Island), Fugle Island (Faroe Archipelago), Mackle Flagga Island (Shetland Islands), Statland Peninsula (62°10¢ N 5°10¢ E).
In the Atlantic Ocean, the coastline of Europe and North America is notable for its considerable indentation, the outlines of the coasts of Africa and South America are relatively simple. The ocean has several Mediterranean seas (Baltic, Mediterranean, Black, Marmara, Azov) and 3 large bays (Mexican, Biscay, Guinea).
The main groups of islands of the Atlantic Ocean of continental origin: Great Britain, Ireland, Newfoundland, Greater and Lesser Antilles, Canaries, Cape Verde, Falkland. A small area is occupied by volcanic islands (Iceland, Azores, Tristan da Cunha, St. Helena, etc.) and coral (Bahamas, etc.).
Peculiarities geographical location The Atlantic Ocean predetermined its significant role in people's lives. This is one of the most developed oceans. Since ancient times, it has been studied by man. Many theoretical and applied problems of oceanology were solved on the basis of research carried out for the first time in the Atlantic Ocean.
Geological structure and bottom topography. Underwater margins of the continents occupy about 32% of the area of the Atlantic Ocean. The most significant areas of the shelf are observed off the coast of Europe and North America. Off the coast of South America, the shelf is less developed and expands only in the Patagonia region. The African shelf is very narrow with depths from 110 to 190 m, complicated by terraces in the south. In high latitudes on the shelf, glacial landforms are widespread, due to the influence of modern and Quaternary continental glaciation. In other latitudes, the shelf surface is leveled by accumulative-abrasion processes. Practically in all shelf areas of the Atlantic there are relic flooded river valleys. From modern forms The relief is most widely represented by sand ridges formed by tidal currents. They are typical for the shelf of the North Sea, the English Channel, North and South America. In the equatorial-tropical latitudes, especially in the Caribbean Sea, near the Bahamas and the coast of South America, coral structures are common.
The slopes of the underwater margin of the continents in the Atlantic Ocean are mainly expressed by steep ledges, often with a stepped profile. They are everywhere dissected by submarine canyons and sometimes complicated by marginal plateaus. The continental foot in most areas is represented by an inclined accumulative plain lying at depths of 3000-4000 m. In some regions, large fans of turbidity flows are observed, among which fans of the Hudson, Amazon, Niger and Congo submarine canyons stand out.
transition zone in the Atlantic Ocean is represented by three areas: Caribbean, Mediterranean and South Sandwich or the Scotia Sea.
The Caribbean region includes the sea of the same name and the deep-water part of the Gulf of Mexico. Numerous uneven-aged island arcs of complex configuration and two deep-water trenches (Cayman and Puerto Rico) are located here. The bottom relief is very complex. Island arcs and submarine ridges divide the Caribbean Sea into several basins with depths of about 5000 m.
The transitional area of the Scotia Sea is a section of the underwater margin of the continents, fragmented by tectonic movements. The youngest element of the region is the island arc of the South Sandwich Islands. It is complicated by volcanoes and bordered on the east by the deep-water trench of the same name.
The Mediterranean region is distinguished by the predominance of the earth's crust of the continental type. The subcontinental earth's crust is found in separate sections only in the deepest basins. The Ionian Islands, Crete, Kasos, Karpathos and Rhodes form an island arc, accompanied from the south by the Hellenic Trench. The Mediterranean transitional region is seismic. Active volcanoes have been preserved here, including such as Etna, Stromboli, Santorini.
Mid-Atlantic Ridge begins off the coast of Iceland called Reykjanes. In plan, it has an S-shape and consists of northern and southern parts. The length of the ridge from north to south is about 17,000 km, the width reaches several hundred kilometers. The Mid-Atlantic Ridge is characterized by significant seismicity and intense volcanic activity. Most earthquake sources are confined to transverse faults. The axial structure of the Reykjanes Ridge is formed by a basalt ridge with weakly expressed rift valleys. At a latitude of 52-53 ° N. sh. it is crossed by the Gibbs and Reykjanes transverse faults. From here begins the North Atlantic Ridge with a well-defined rift zone and numerous transverse faults. In the equatorial ridge is especially broken large quantity faults and has a sublatitudinal strike. The South Atlantic Ridge also has a well-defined rift zone, but is less dissected by transverse faults and is more monolithic than the North Atlantic Ridge. The volcanic plateaus of the Ascension, the islands of Tristan da Cunha, Gough, and Bouvet are confined to it. At Bouvet Island, the ridge turns east, passes into the African-Antarctic and merges with the ridges of the Indian Ocean.
The Mid-Atlantic Ridge divides ocean floor into two almost equal parts. They, in turn, are crossed by transverse uplifts: the Newfoundland Ridge, the Ceara Rise, Rio Grande, the Cape Verde Islands, Guinea, Whale Ridge, etc. There are 2,500 individual seamounts in the Atlantic Ocean, of which about 600 are located within the ocean floor. A large group of seamounts is confined to the Bermuda Plateau. Guyots and volcanic mountain ranges are widely represented in the Azores region. Mountain structures and uplifts divide the ocean floor into deep-water basins: Labrador, North American, Newfoundland, Brazilian, Iberian, Western European, Canary, Angolan, Cape. The relief of the bottom of the basins is characterized by flat abyssal plains. In the areas of basins adjacent to mid-ocean ridges, abyssal hills are typical. In the north of the Atlantic Ocean, as well as in tropical and subtropical latitudes, there are many banks with a depth of 50-60 m. Over a larger area of the ocean floor, the thickness of the sedimentary layer exceeds 1 km. The oldest deposits of the Jurassic age.
Bottom sediments and minerals. Among the deep-water sediments of the Atlantic Ocean, foraminifera predominate, occupying 65% of the area of the ocean floor. Due to the warming effect of the North Atlantic Current, their range extends far to the north. Deep-water red clay occupies about 26% of the ocean floor area and occurs in the deepest parts of the basins. In the Atlantic Ocean, pteropod deposits are more common than in other oceans. Radiolarian muds are found only in the Angolan Basin. In the south of the Atlantic, siliceous diatomaceous oozes are widely represented, with a silica content of up to 72%. In some areas of the equatorial-tropical latitudes, coral silts are observed. In shallow areas, as well as in the Guinean and Argentine basins, terrigenous deposits are well represented. On the shelf of Iceland and the Azores plateau, pyroclastic deposits are widespread.
Bottom sediments and bedrocks of the Atlantic Ocean have a wide range of minerals. In the coastal waters of South West Africa there are deposits of gold and diamonds. Huge deposits of monazite sands have been discovered off the coast of Brazil. Large deposits of ilmenite and rutile are observed off the coast of Florida, iron ore - off Newfoundland and Normandy, cassiterite - off the coast of England. Iron-manganese nodules are scattered on the ocean floor. Oil and gas fields are being developed in the Gulf of Mexico, Biscay and Guinea, the North Sea, the Maracaibo lagoon, the Falkland Islands and a number of other places.
Climate The Atlantic Ocean is largely determined by the peculiarities of its geographical position, its peculiar configuration, and the conditions of atmospheric circulation.
Annual amount of total solar radiation varies from 3000-3200 MJ/m 2 in subarctic and antarctic latitudes to 7500-8000 MJ/m 2 in equatorial-tropical latitudes. The value of the annual radiation balance ranges from 1500-2000 to 5000-5500 MJ/m 2 . In January, a negative radiation balance is observed north of 40°N. sh.; in July - south of 50 ° S. sh. The balance reaches its maximum monthly value (up to 500 MJ/m2) in the tropics, in January in the southern hemisphere, and in July in the northern hemisphere.
The baric field over the Atlantic Ocean is represented by several centers of action of the atmosphere. In the temperate latitudes of the northern hemisphere, the Icelandic low is located, which is more active in winter. In the subpolar region of the southern hemisphere, the Antarctic Low Pressure Belt stands out. In addition, the formation of the climate of the high latitudes of the Pacific Ocean is significantly influenced by the Greenland High and the Antarctic High Pressure Region. In the subtropical latitudes of both hemispheres above the ocean, there are centers of two permanent baric maxima: the North Atlantic (Azores) and the South Atlantic. Along the equator is the equatorial depression.
The location and interaction of the main baric centers determines the system of prevailing winds in the Atlantic Ocean. At high latitudes, easterly winds are observed off the coast of Antarctica. In temperate latitudes, westerly winds predominate, especially in the southern hemisphere, where they are most constant. These winds cause a significant frequency of storms throughout the year in the southern hemisphere and in winter in the northern hemisphere. The interaction of subtropical highs and equatorial depression causes the formation of trade winds in tropical latitudes. The frequency of trade winds is about 80%, but they rarely reach storm speed. In the tropical part of the northern hemisphere in the Caribbean Sea, the Lesser Antilles, the Gulf of Mexico and the Cape Verde Islands, tropical cyclones are observed, with hurricane-force winds and heavy rainfall. On average, there are 9 hurricanes per year, most of which occur from August to October.
Seasonal changes are clearly visible in the Atlantic Ocean air temperature. The warmest months are August in the northern and February in the southern hemispheres, while the coldest months are February and August, respectively. In winter, in each hemisphere, the air temperature in the equatorial latitudes drops to +25 °С, in the tropical - to +20 °С and temperate - to 0 - - 6 °С. The annual amplitude of air temperature near the equator is not more than 3 °С, in subtropical regions up to 5 °С, in temperate regions up to 10 °С. Only in the extreme northwest and south of the ocean, where the influence of the adjacent continents is most pronounced, does the average air temperature of the coldest month drop to -25 °C, and the annual temperature amplitude reaches 25 °C. In the Atlantic Ocean, there are noticeable anomalies in the sublatitudinal distribution of air temperature near the western and eastern coasts of the continents, due to the influence of ocean currents.
Differences in atmospheric circulation conditions over the Atlantic Ocean affect the nature of cloudiness and precipitation in its waters. The maximum cloudiness over the ocean (up to 7-9 points) is observed in high and temperate latitudes. In the equatorial region, it is 5-b points. And in subtropical and tropical latitudes it decreases to 4 points. The amount of precipitation in polar latitudes is 300 mm in the north of the ocean and 100 mm in the south, in temperate latitudes it rises to 1000 mm, in subtropical and tropical latitudes it varies from 100 mm in the east to 1000 mm in the west, and in equatorial latitudes it reaches 2000-3000 mm.
A characteristic phenomenon for the temperate latitudes of the Atlantic Ocean are dense mists formed by the interaction of warm air masses with a cold water surface. Most often they are observed in the area of the island of Newfoundland and off the southwestern coast of Africa. In the tropical zone, fogs are rare and most likely around the Cape Verde Islands, where the dust carried from the Sahara serves as condensation nuclei for atmospheric water vapor.
hydrological regime. surface currents in the Atlantic Ocean are represented by two extensive anticyclonic gyres with centers near 30° north and south latitude.
The northern subtropical gyre is formed by the Northern Tradewind, Antilles, Florida, Gulf Stream, North Atlantic and Canary Currents, the southern one by the South Tradewind, Brazil, West Winds and Benguela. Between these gyres is the Equatorial Countercurrent (at 5-10°N), which passes into the Guinea in the east. The Lomonosov subsurface countercurrent is located under the South Equatorial Current. It crosses the ocean from west to east at a depth of 300-500 m, reaches the Gulf of Guinea and fades south of it. Under the Gulf Stream at a depth of 900-3500 m, at a speed of up to 20 km / h, a powerful subsurface Western Border bottom countercurrent passes, the formation of which is associated with a bottom runoff of cold water from high latitudes. In the northwest of the Atlantic Ocean, a cyclonic circulation is distinguished, consisting of the North Atlantic, Irminger, East Greenland, West Greenland and Labrador currents. In the eastern part of the Atlantic Ocean, the deep Lusitana current is well expressed, which is formed by the bottom runoff of Mediterranean waters through the Strait of Gibraltar.
Excitement in the Atlantic Ocean depends on the direction, duration and speed of the prevailing winds. The area of greatest wave activity is located north of 40°N. sh. and south of 40°S. sh. Wave height during long and very winds sometimes reaches 22-26 m. Waves 10-15 m high are relatively often observed. Every year, during the passage of tropical cyclones, waves 14-16 m high are formed. In the northern part of the Atlantic in the Antilles, Azores, Canary islands and off the coast of Portugal, storm surges 2-4 m high are quite often observed.
Most of the Pacific tides semi-diurnal. In the open ocean, the tide height usually does not exceed 1 m (St. Helena - 0.8 m, Ascension Island - 0.6 m). Off the coast of Europe in the Bristol Bay, tides reach 15 m, in the Gulf of Saint-Malo - 9-12 m. with.
Average annual surface water temperature The Atlantic Ocean is 16.9 °C. Its annual amplitude in the equatorial-tropical latitudes is no more than 1-3 °C, subtropical and temperate latitudes - 5-8 °C, polar - about 4 °C in the north and up to 1 °C in the south. In general, the temperature of the surface waters of the Atlantic decreases from the equator to high latitudes. In winter, in February in the Northern Hemisphere and in August in the Southern Hemisphere, it changes from +28 °С at the equator to +6 °С at 60° N. and -1°C at 60°S latitude, in summer, in August in the Northern Hemisphere and in February in the Southern Hemisphere: from +26 ° С at the equator to +10 ° С at 60 ° N and about 0 ° С at 60 ° S. sh. Ocean currents cause significant anomalies in the temperature of surface waters. Due to the significant inflow of warm waters from low latitudes, the northern area of the ocean is much warmer than its southern part. In some areas near the coasts of the continents, there are differences in the water temperature of the western and eastern sectors of the ocean. So, at 20° N. sh. the presence of warm currents maintains the water temperature in the west of the ocean at 27 ° C, while in the east it is only 19 ° C. Significant horizontal temperature gradients of the surface layer are observed at the meeting points of cold and warm currents. At the junction of the East Greenland and Irminger currents, a temperature difference of 7 ° C within a radius of 20-30 km is a common occurrence.
The Atlantic Ocean is the saltiest of all oceans. Medium salinity its waters is 35.4‰. The highest water salinity up to 37.9 ‰ is observed in tropical latitudes in the east of the Atlantic, where there is little precipitation and maximum evaporation. In the equatorial zone, salinity drops to 34-35 ‰, in high latitudes it drops to 31-32 ‰. The zonal distribution of salinity is often disturbed as a result of the movement of water by currents and the inflow of fresh water from land.
ice formation in the northern part of the Atlantic Ocean occurs mainly in the inland seas of temperate latitudes (Baltic, Northern, Azov) and the Gulf of St. Lawrence. AT open ocean a large amount of floating ice and icebergs is carried out of the Arctic Ocean. Floating ice in the northern hemisphere reaches 40°C even in July. sh. In the south of the Atlantic, ice and icebergs form in Antarctic waters. The main source of icebergs is the Filchner Ice Shelf in the Weddell Sea. South of 55°S sh. floating ice is present throughout the year.
Water transparency in the Atlantic Ocean varies widely. It decreases from the equator to the poles and from the coasts to the central part of the ocean, where the water is usually homogeneous and transparent. The maximum transparency of water in the Weddell Sea is 70 m, Sargasso Sea - 67 m, Mediterranean - 50, Black - 25 m, North and Baltic 18-13 m.
Surface water masses in the Atlantic Ocean have a thickness of 100 m in the Southern Hemisphere to 300 m in the equatorial-tropical latitudes. They are characterized by significant seasonal variability of properties, vertical uniformity of temperature, salinity and density. Subsurface waters fill depths up to about 700 m and differ from surface waters in increased salinity and density.
Intermediate water masses in the northwestern part of the ocean are formed as a result of immersion of cold waters coming from high latitudes. Salt waters from the Mediterranean Sea form a special water intermediate mass. In the Southern Hemisphere, intermediate water is formed by subsidence of cooled Antarctic waters and is characterized by low temperature and low salinity. It moves to the north, first at a depth of 100-200 m, gradually sinks further north of 20°N. sh. at a depth of 1000 m it mixes with the northern intermediate water.
The deep water masses of the Atlantic Ocean consist of two layers of different genesis. The upper horizon is formed by the subsidence of warm and salty Mediterranean waters. In the northern part of the ocean, it is located at depths of 1000-1250 m, in the Southern Hemisphere it drops to 2500-2750 m and wedges out at about 45 ° S. sh. The lower layer of deep water is formed mainly as a result of the sinking of the cold waters of the East Greenland Current from depths of 2500-3000 m in the northern hemisphere to 3500-4000 m at 50 ° S. sh., where it begins to be displaced by bottom Antarctic waters.
Bottom water masses are formed mainly on the Antarctic shelf and gradually spread over the ocean floor. North of 40°N the presence of bottom water coming from the Arctic Ocean is noted. They are characterized by uniform salinity (34.6-34.7 ‰) and low temperature (1-2 °C).
organic world. The Atlantic Ocean is inhabited by a variety of plant and animal species. The phytobenthos of the temperate and polar latitudes of the Atlantic is characterized by brown and red algae. In the equatorial-tropical zone, the phytobenthos is represented by numerous green algae (caulerpa, wallonia, etc.) of the red algae, lithotamnia predominate, and of the brown ones, Sargassum algae. On the littoral of the European coast, sea grass - zostera - is widely represented.
Phytoplankton of the Atlantic Ocean has 245 species. They are represented by an approximately equal number of peridine species, coccolithophorids, and diatoms. The latter have a clearly defined zonal distribution and live mainly in temperate latitudes. The fauna of the Atlantic has a smaller number of species than in the Pacific Ocean. But some families of fish (codfish, herring, etc.) and mammals (seals, etc.) are much richer in the Atlantic Ocean. The total number of species of whales and pinnipeds is about 100, fish are more than 15,000. Of the birds, albatrosses and petrels are common. The distribution of animal organisms has a well-pronounced zonal character, and not only the number of species, but also the total biomass changes zonally.
In the subantarctic and temperate latitudes, the biomass reaches its maximum, but the number of species is much less than in the equatorial-tropical zone. Antarctic waters are poor in species and biomass. The fauna of the subantarctic and temperate zones of the southern part of the Atlantic Ocean is dominated by: in zooplankton - copepods, pteropods, among mammals - whales and pinnipeds, among fish - nototenidae. In the temperate latitudes of the Northern Hemisphere, foraminifers and copepods are most characteristic of zooplankton. Of the commercial fish, the most important are herring, cod, haddock, halibut, and sea bass.
In the equatorial-tropical zone, zooplankton consists of numerous species of foraminifera and pterapods, several species of radiolarians, copepods, larvae of mollusks and fish. These latitudes are characterized by sharks, flying fish, sea turtles, jellyfish, squids, octopuses, corals. Commercial fish are represented by mackerel, tuna, sardines, anchovies.
The deep-sea fauna of the Atlantic Ocean is represented by crustaceans, echinoderms, specific genera and families of fish, sponges, and hydroids. Endemic species of polychaetes, isopods and holothurians live in the ultraabyssal zone.
There are four biogeographic regions in the Atlantic Ocean: Arctic, North Atlantic, Tropical Atlantic and Antarctic. Of the fish for the Arctic region are characteristic - haddock, cod, herring, saury, sea bass, halibut; North Atlantic - cod, haddock, saithe, various flounders, in more southern regions - wrasse, mullet, mullet; Tropical-Atlantic - sharks, flying fish, tuna, etc.; Antarctic - noto-shadow.
The following are distinguished in the Atlantic Ocean physical-geographical zones and regions. Northern subpolar belt: Labrador Basin, Denmark Strait and waters of Southeast Greenland, Davis Strait; northern temperate zone: the area of the American shelf, the Gulf of St. Lawrence, the English Channel and the Pas de Calais, the Irish Sea, the Celtic Sea, the North Sea, the Danish (Baltic) Straits, the Baltic Sea; northern subtropical belt: Gulf Stream, Gibraltar region, Mediterranean Sea, Black Sea straits and Sea of Marmara, Black Sea, Sea of Azov; northern tropical belt: West African Region, American Mediterranean Sea with subregions: Caribbean Sea, Gulf of Mexico, Bahamas Subregion; equatorial belt: Gulf of Guinea, Western Shelf; southern tropics: Congo region; southern subtropical belt: La Plata region, South West Africa region; southern temperate zone: Patagonian region; southern subpolar belt: Sea of Scotia; south polar belt: Weddell Sea.
The vast water spaces of the planet, covering most of it and the surrounding islands and continents, are called oceans. Among them, the largest are the Atlantic and the Pacific. These are two giants that people know far from everything about. Mankind knows where the Atlantic Ocean is located, what are its boundaries, underwater inhabitants, relief, etc.
Atlantic Ocean
The Atlantic Ocean is considered the second largest after the Pacific. However, it is better studied and mastered, in comparison with other water areas. And where is the Atlantic Ocean, what are its boundaries? This giant is located along the length of the entire planet: in the east, the borders are North and South America, in the west - Europe, Africa. In the south, the Atlantic waters pass into the Southern Ocean. In the north, the giant is bounded by Greenland.
In those places where the Atlantic Ocean is located, there are practically no islands, which distinguishes this water area from others. Another distinguishing feature is the complex bottom topography and broken coastline.
Atlantic Ocean parameters
If we talk about the area, then the water area occupies more than ninety million square kilometers. Where the Atlantic Ocean is located, huge water reserves are concentrated. According to scientists, there are almost 330 million cubic kilometers of water in this basin.
The Atlantic Ocean is quite deep - the average depth reaches 3800 meters. In the place where the Puerto Rico Trench is located, the depth exceeds eight kilometers.
There are two parts in the Atlantic Ocean: northern and southern. The conditional border between them runs along the territory of the equator.
Bays, seas and currents
The area of the seas and bays accounts for about sixteen percent of the total ocean area: about fifteen million square kilometers, with a volume of thirty million cubic kilometers. The most famous seas of the Atlantic are: North, Mediterranean, Aegean, Black, Azov, Caribbean, Labrador Sea, Baltic. By the way, where is the Baltic Sea in the Atlantic Ocean? It is located not far from the Arctic Circle, at 65°40"N (northern point), and in the south the sea is defined by a boundary at 53°45"N. sh., located near Wismar. In the west, the border is located near Flensburg, in the east - in the region of St. Petersburg.
Many are interested in the question: "Where is the North Atlantic Current in the Atlantic Ocean and what other currents are there?" The ocean is huge and stretches from north to south, across all hemispheres. Because of this particular location, different areas have different climates. But not only the proximity of the poles affects the weather: it is also influenced by currents that carry large volumes of ocean water. Thanks to them, the west is warmer than the east. This feature is associated with the course of the Gulf Stream and its branches - Antilles, Brazilian, North Atlantic. In the eastern part there is not only a warm current, but also a cold one - the Bengal and Canary.
The North Atlantic Current is the northeast extension of the Gulf Stream. It starts at the Great Newfoundland Beam. West of Ireland, the current is divided into two parts, one of which is the Canary.
Northern part of the ocean
The northern border of the Atlantic has a rugged coastline. A small part has a connection with the North Arctic Ocean: it communicates with it by several narrow straits. In the northeast is Davis Strait, which connects the Baffin Sea with the ocean. Closer to the center of the northern border is the Denmark Strait, and between Norway and Iceland, the border is the Norwegian Sea.
In the southwest of the North Atlantic Ocean is the Gulf of Mexico, which communicates with the Gulf of Florida. Also in this part is the Caribbean Sea. And besides, there are many other famous bays: Hudson, Barnegat, etc. The largest islands are located in this part of the basin: Cuba, Haiti, and the British Isles. There are also island groups closer to the east, but they are small. Among them, the most popular are the Canaries, Azores, Cape Verde. To the west are the Bahamas.
Southern part of the water area
The southern borders of the ocean are not as strongly indented as in the northern part. There are no seas here, but there is a very large gulf - Guinea. The most remote point of the Atlantic in the south is Tierra del Fuego, framed by small islands.
There are no large islands in the southern part of the ocean, but there are separately located formations. Examples are the Ascension Islands and Saint Helena.
There are also currents in the south, but here the waters move counterclockwise. The most powerful and largest current of this part is the South Tradewind, which branches off the coast of Brazil. One of its branches goes to the shores of South America, and the second one connects with the Atlantic current and moves to the east, where part of the current separates and passes into the Bengal current.
There are two huge oceans on Earth, and knowing where the Pacific and Atlantic oceans are, we can say for sure that these two great natural creatures will never meet.
It is its great length (16 thousand km) from north to south - from the Arctic to the Antarctic latitudes and a relatively small width, especially in equatorial latitudes, where it does not exceed 2900 km. The average depth of the ocean is 3597 m, the maximum is 8742 m (Puerto Rico Trench). It was the Atlantic Ocean with the peculiarities of its 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, given its above-water part, by more than 4000 m. The Mid-Atlantic Ridge is young, tectonic processes are active in it and to the present, as evidenced by earthquakes, surface and underwater volcanism.
Unlike other oceans, there are significant areas of continental crust in the Atlantic (off the coast of Scotland, Greenland, the Blake Plateau, at the mouth of La Plata), which indicates 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 the presence of its two types (glacial and normal) and the unequal width off the coasts 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, wide development of glacial exaration and accumulative relief. South of the islands of Newfoundland and Nova Scotia on the American side and the English Channel on the European side, the glacial shelf is replaced by a normal one. The surface of such a shelf is leveled by accumulative-abrasive processes, which from the beginning of the Quaternary period to the present have influenced 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 shelf of South America 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, passing towards the ocean either as a series of terraces with inclinations of 1–2°, or as a steep ledge with inclinations of 10–15°, for example, near the Florida and Yucatan peninsulas.
From Trinidad to the mouth of the Amazon, this is a dissected ledge with depths up to 3500 m with two ledges: the Guiana and Amazon marginal plateaus. To the south, the ledge is stepped with blocky forms. Off the coast of Uruguay and Argentina, the slope has a concave shape and is 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.
Transitional zones are areas of articulation 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 separated by the expanding Atlantic. In the west, the role of the marginal sea is played by the Caribbean Sea, the Greater and Lesser Antilles Islands 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 borders from the east the South Antilles underwater ridge with chains of volcanic islands forming an arc (South Georgia, South Sandwich Islands, etc.). At the eastern foot of the ridge there is a deep-water trench - Yuzhno-Sandvichev (8264 m).
The mid-ocean ridge is the most striking geographic feature of the Atlantic Ocean.
The northernmost link of the Mid-Atlantic Ridge itself - the Reykjanes Ridge - at 58 ° N. sh. bounded by the sublatitudinal Gibbs Fault Zone. The ridge has a distinct rift zone and flanks. At o. The Iceland crest of the ridge has steep ledges, and the Gibbs Fault is a double chain of trenches with structures offset up to 350 km.
District about. Iceland, the surface part of the North Atlantic Ridge, is a very active rift structure passing through the entire island, with spreading, as evidenced by the basalt composition of the entire ridge shaft, the youth of sedimentary rocks, the symmetry of anomalous magnetic lines, an increased heat flow from the bowels, the presence of numerous small earthquakes, breaks in structures (transform faults), etc.
On a physical map, the pattern of the Mid-Atlantic Ridge can be traced along the islands: Fr. 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 and Cape Town) and about. Bouvet. Having rounded Africa, the Mid-Atlantic Ridge joins with the ranges.
The northern part of the Mid-Atlantic Ridge (to the Azores) has a width of 1100-1400 km and represents 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 sloping surfaces with block-block-ridge relief. North-east of the Azores - two ridges (Poliser 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 up to the equator also has the form of an arc, but its convex part is turned to the west. The width of the ridge here is 1600-1800 km, narrowing to 900 km towards the equator. The entire length of the rift zone and flanks is dissected by transform faults in the form of troughs, some of which also extend into the adjacent basins of the ocean floor. The most well-studied are the Okeanograph, Atlantis, and Romany transform faults (at the equator). The displacement of structures in the faults is within 50-550 km with a depth of up to 4500 m, and in the Romansh 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, the rift zone is developed with depths of 3500-4500 m.
Faults of the southern part - Cheyne, Ascension, Rio Grande, Falkland. On the eastern flank, on the underwater plateaus, the mountains of Bagration, Kutuzov, and Bonaparte rise.
In the 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 basins with a flat bottom, successively replacing each other from north to south. They are separated by small underwater ridges, rapids, uplifts (for example, Rio Grande, Kitovy), successively replacing each other from north to south.
In the extreme northwest is the Labrador Basin, more than 4,000 m deep - a flat abyssal plain with a thick two-kilometer sedimentary cover. Next is the Newfoundland Basin (the maximum depth is more than 5000 m), with an asymmetric bottom structure: in the west it is a flat abyssal plain, in the east it is hilly.
The North American Basin is the largest in size. In the center is the Bermuda Plateau with a thick layer of precipitation (up to 2 km). Drilling revealed Cretaceous deposits, 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 limestone and represent a giant atoll, which is rare for the Atlantic Ocean.
To the south is the Guyana Basin, part of which is occupied by the threshold of Para. It can be assumed that the threshold has an 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 Brazil Basin with a range of seamounts, one of which is home to the only coral atoll in the South Atlantic, Rocas.
The largest basin in the South Atlantic is the African-Antarctic basin, from the Scotia Sea to the Kerguelen Rise, its length is 3,500 miles, its width is about 800 miles, and its maximum depth is 6,972 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, near 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 has a thickness of 1-2 km.
Ridges play an important role in the ocean as ecological 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, occupying about 65% of the area of the ocean floor, in second place are 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 Argentine basins.
Seabed sediments and bedrock 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, the North Sea, the Bays of Biscay and the Bay of Guinea, the Maracaibo lagoon, and 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 fields 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, the 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 per 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 world's largest deposit. Ilmenite and rutile deposits are known off the coast of Florida (USA). The largest placers of ferromanganese nodules and deposits of phosphorites 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 large meridional extent, the features of the formation of the baric field, and the peculiarity of the configuration (water areas are larger in temperate latitudes than in equatorial-tropical ones). On the northern and southern margins there are huge regions of cooling and the formation of high atmospheric pockets. Over the ocean area, constant areas of low pressure are also formed in the equatorial and temperate latitudes and high pressure - in the subtropics.
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 the 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, westerly winds dominate, with significant speeds, in the Southern Hemisphere often turning into a storm - the so-called "roaring forties" latitudes.
The distribution of atmospheric pressure and features of air masses affect the nature of cloudiness, the regime and amount of precipitation. Cloudiness over the ocean varies by zone: the maximum amount of clouds near the equator with a predominance of cumulus and cumulonimbus forms, the least cloudiness - in tropical and subtropical latitudes, in temperate latitudes the number of clouds increases again - stratus and stratified-nimbus forms dominate here.
Dense fogs are very characteristic of the temperate latitudes of both hemispheres (especially the Northern), formed when warm air masses and cold waters of the ocean come into contact, as well as when waters of 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 the dust carried from the Sahara serves as condensation nuclei for atmospheric water vapor. Fogs are also common off 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, causing hurricane-force winds and heavy showers. Tropical cyclones often develop from small depressions that move from the African continent to the Atlantic Ocean. Gaining strength, they become especially dangerous for the islands of 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 large north-south extent, small width near the equator, and wide connection with.
The average surface water is 16.9°C (according to other sources - 16.53°C), while in the Pacific - 19.1°C, Indian - 17°C. 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 of the North Atlantic (6.3°C) is somewhat higher than that of the South (5.6°C).
Seasonal temperature changes are also well observed. The lowest temperature is recorded in the north and in the south of the ocean, and the highest - vice versa. However, the annual temperature amplitude at the equator is no more than 3°С, in subtropical and temperate latitudes - 5-8°С, in subpolar latitudes - about 4°С. 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 at the meeting points of cold and warm currents, such as the East Greenland and Irminger, where a temperature difference of 7°C over a distance of 20-30 km is a common occurrence.
Annual temperature fluctuations are clearly seen 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 is on average 35.4% o, 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 N.S. sh., in the South - between 20 and 25 ° S. sh. The trade wind circulation dominates here, there is little precipitation, while evaporation makes up a layer of 3 m. Fresh water from land almost does not come. The salinity is slightly higher than average in the temperate latitudes of the Northern Hemisphere, where the waters of the North Atlantic Current rush. Salinity in equatorial latitudes - 35% o. There is a change in salinity with depth: at a depth of 100-200 m it is 35.4% o, which is associated with the subsurface Lomonosov current. It has been established that the salinity of the surface layer in some cases does not coincide with the salinity at depth.
Sharp drops in salt content are also observed when currents of different temperatures meet. For example, south of Newfoundland at the meeting of the Gulf Stream and the Labrador Current at a short distance, salinity drops from 35% o to 31-32% o.
The existence in the Atlantic Ocean of underground fresh water - submarine sources (according to I. S. Zetzker) - 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. 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 disturbances or areas of karst development. When the pressure of groundwater exceeds the pressure of a column of sea water, unloading occurs - an outpouring of groundwater to the surface. A well was recently drilled on the continental slope of the Gulf of Mexico off the coast of Florida. When drilling a well, a column of fresh water 9 meters high escaped from a depth of 250 m. The search and study of submarine sources is just beginning.
Optical properties of water
Transparency, which determines the illumination of the bottom, the nature of the heating of the surface layer, is the main indicator of optical properties. It varies over a wide range, 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 is far from the coast, in the tropics it 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: the upper mixed layer, a layer of reduced transparency and deep transparent ones. Depending on the 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 off the coast of North Africa to 20 m 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 high content plankton. The boundaries between layers with different transparency are often blurry and fuzzy. Against the mouth of the river The Congo also has a three-layer profile, to the north and south - a two-layer one. In the Guinean 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.
Water dynamics
They learned about the existence in the ocean relatively recently, even the Gulf Stream became known only at the beginning of the 16th century.
In the Atlantic Ocean, there are currents of various origins: drift currents - the North and South Trade Winds, Western drift or Western Winds (with a flow rate of 200 sverdrups), runoff (Florida), tidal. 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 the trade winds. These are the North and South Tradewinds, moving from east to west. At the eastern shores of both Americas, they branch out. In summer, the Equatorial countercurrent manifests itself most effectively, its axis moves from 3° to 8° N. sh. The North Tradewind current near the Antilles is divided 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 flow is 90 sverdrups, the minimum is 60, the average is 69. The water flow in the Gulf Stream is 1.5-2 times greater 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 an isotherm of 15°C at a depth of 200 m. Salinity is more than 35% o, in the southern branch - 35.1% o. The main stream reaches 55°W. e. Prior to this segment, there is almost no transformation of the water mass on the surface; at a depth of 100-300 m, the properties of the flow do not change at all. At Cape Hatteras (Gateras), the waters of the Gulf Stream divide into a series of narrow, strongly meandering streams. One of them, with an expenditure of about 50 Sverdrups, goes to the Newfoundland Bank. From 41°W The North Atlantic Current begins. Rings are observed in it - vortices moving in the direction of the general movement of 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, meeting with the cold runoff East Greenland Current. The West Greenland current in the south connects with the Labrador Current, which, mixing with the warm current, leads to a deterioration in meteorological conditions in the area of the Newfoundland bank. The water temperature in January is 0°С, in July - 12°С. The Labrador Current often carries icebergs into the ocean south of Greenland.
The South Equatorial Current off the coast of Brazil bifurcates into the Guiana and Brazilian Currents, to the north the Guiana Current merges with the Northern Equatorial Current. Brazilian in the south about 40 ° S. sh. connects with the course of the West Winds, from which the cold Benguela current departs to the shores of Africa. It merges with the South Tradewind, and the southern ring of currents closes. Towards the Brazilian from the south comes the cold Falkland.
Opened 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 Northern Equatorial Current, eddies of an anticyclonic nature were discovered with a speed of 5.5 cm/sec. In the ocean, there are eddies of large diameters - 100-300 km (medium ones have a diameter of 50 km, small ones - 30 km). The discovery of these eddies, called synoptic, is of great importance for laying the course of ships. In compiling maps with the designation of the direction and speed of movement of synoptic vortices, artificial Earth satellites are of great help.
The dynamics of ocean waters has a huge energy potential, which until now is almost not used. And although the ocean is in most cases less concentrated, less convenient to use than the energy of rivers, scientists believe that these are inexhaustible resources, constantly renewed. In the first place is the energy of the tides.
The first successfully operating tidal water mills were built in England (in Wales) as early as the 10th-11th centuries. Since then, they have been constantly built on the shores of Europe and North America. However, serious energy projects appeared in the 1920s. The possibilities of using tides as energy sources are most likely off the coast of France, Great Britain, the USA,. The first small-capacity tidal power plants are already in operation.
Work is underway to harness the thermal energy of the oceans. The surface layer of water in tropical latitudes can warm up to minor seasonal fluctuations. At a depth (300-500 m) the water temperature is only 8-10°C. An even sharper 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 (Côte d'Ivoire).
