The Atlantic Ocean, which occupies the second largest area among the oceans of the world, was the first to attract the attention of researchers and for a long time remained the most studied. Currently, specialists in the field of geotectonics tend to believe that the Atlantic Ocean is possibly the youngest.

There are subtle signs of the existence in this part of the globe of the meridional water space until the late Mesozoic, i.e., about 100 million years ago, and the connection of the South Atlantic with the Indian Ocean, as evidenced by the organic remains of the Upper Cretaceous. As a result of detailed and systematic studies of the northern and southern basins of the Atlantic Ocean carried out by the Meteor expedition, theories of the origin and structure of the Atlantic Ocean appeared. Cowber (1928) was the first to suggest the existence of a system of mountain ranges encircling the globe, which he considered as an orogenic belt (as opposed to a taphrogenic Hysen's hypothesis).

According to the data of Kossin (1921), which are usually referred to, the area of ​​the Atlantic Ocean (the ocean itself) is approximately 8.2*10^7 km2, and including the marginal seas (Caribbean, Mediterranean, etc.) is about 10.6*10^7 km3. The average depth in the first case is 3920 m and in the second 3332 m.

The Atlantic Ocean is not as deep as the Pacific and Indian Oceans, mainly because of the extensive continental shoals extending to the north and a thick layer of sediments.

According to Murray (1888), the total area of ​​runoff into the Atlantic Ocean is about 3.5 x 10^7 km2, and including the Arctic, about 5.0 x 10^7 km2, which is four times the area of ​​runoff into the Indian Ocean and almost four times drainage area in the Pacific Ocean. At present, the water balance of the World Ocean can only be maintained with a constant flow from the Atlantic Ocean to other oceans.

In the Atlantic Ocean, unlike the Indian and Pacific Oceans, there are only a small number of seamounts and guyots and no coral atolls. Parts of the coast for a long distance are devoid of coastal reefs, even under favorable conditions. However, coral banks are known in the cold waters of the Atlantic Ocean.

The decrease in water temperature during the Pleistocene period and the isolation of the Atlantic Ocean from latitudinal currents as a result of tectonic movements of the earth's crust in the Middle and Late Tertiary periods determined a rather poor and "isolated" benthic fauna, which contrasts with the "universal" nature of benthos in the Cretaceous and Early Tertiary periods.

The main groups of islands of continental origin, they are located off the coast (Greenland, the Canadian Arctic Archipelago, Svalbard, Great Britain, the Falkland (Malvinas) Islands, the Skoschai arc, etc.). Several oceanic islands occupy only 5.0 * 106 km2 Assension, St. Helena, Tristan da Cunha, Gough Island, Bouvet Island, etc. These islands are mainly of volcanic origin.

Basins of the Atlantic Ocean

Western Atlantic

Labrodor Basin located between the Labrador Peninsula, Greenland and Newfoundland. This basin extends well beyond the Labrador Sea and includes most of the Irminger Sea. Turbidity flows, carrying sedimentary material deposited on the bottom, flow down the mid-ocean canyon to the Som abyssal plain.

Newfoundland basin located between Newfoundland and the Azores. It is partially separated from the adjacent basins in the south. In the southwest, this basin is bounded by the Southeast Newfoundland Rise. Its northern boundary runs along a line from the Flemish Cap bank in the northeast to the western branch of the Mid-Atlantic Ridge, at about 55°N. sh., which crosses the mid-ocean canyon from north to south, connecting the Labrador Basin with the abyssal plain of Catfish.

North American Basin is a very large depression which, strictly speaking, is not a true depression. It is located near the underwater Bermuda Upland, as well as several abyssal plains that limit the upland on three sides - Som from the northeast, Hatteras from the west and Nares (900 thousand km2) from the southeast. The last two plains at 24° N. latitude, 68° W e. divides the abyssal gorge Vema. The Black Bahama Outer Range separates the Hatteras Abyssal Plain from the narrow Black Bahama Basin and Abyssal Plains. this basin includes the Puerto Rico Trench, a typical deep-water trench of the Atlantic Ocean. Within the trench are two areas with maximum depths, one of which is sometimes called the Brownson Basin. the other was called the Milwaukee Trench (after the name of the ship that first discovered it), but even greater depths were later discovered.

Guiana Basin located near the Venezuelan, Guiana coasts and the Amazonian coast of Brazil. In the basin, there are: in the west - the abyssal plain of Demerara (335 thousand km2), on which sediments are accumulated carried out by the Orinoco River, the Guiana rivers and partly by the Amazon runoff; in the east - the abyssal plain of Keara, separated from the abyssal by the early Demerara by the huge Amazonian abyssal cone, which is also its main source of sedimentary material.

brazilian basin (Tizard Depression) is located off the east coast of Brazil. It is bounded in the north by the Para (now Belem) uplift, which continues outside the basin with a partially volcanic ridge topped by the islets of Fernando de Noronha and Rocas. At the northern end of the ridge there is a vast lowering of the bottom - the abyssal plain of Recife), however, south of the volcanic uplift of Trindade, the area of ​​​​the abyssal plain is small.

Argentine Basin. To the southwest of the underwater Rio Grande highland there is a long narrow Argentine abyssal plain (200 thousand km2), to the east of it there is a wide gently sloping Argentine uplift, an area of ​​insignificant abyssal hills.

Atlantic-Antarctic catlovina (South Atlantic polar basin; African-Antarctic basin.) Stretching across the entire South Atlantic from the Weddell Sea to the Indian Ocean, it includes a long depression, the Weddell abyssal plain. The isolated depression between South Sandwich and Bouvet Islands is the abyssal Sandwich Plain. Another typical deep-sea trench of the Atlantic Ocean, the South Sandwich Trench (or Sandwich Trench), with the greatest depth of 8264 m, was found here. It is separated by several ridges from the Atlantic-Antarctic Basin. Within the Skosh Sea there are numerous small closed basins that do not have names.

East Atlantic

West European Basin (North East Atlantic Basin). Two interconnected abyssal plains were found in the basin: Porcupine to the west of Great Britain and Biscay (80 thousand km2), which in turn in the south is connected with the Iberian abyssal plain. These abyssal plains are described by Lawton as part of a scarp-like system that gradually descends southward through a series of narrow gorges and channels.

Iberian Basin (Spanish Basin) is located to the west of Spain (name
The "Iberian Basin" had another basin located in the western Mediterranean Sea, east of Spain; to avoid confusion, the latter was given the name "Balearic Basin") and is connected by the abyssal Theta Gorge with the Biscay abyssal plain. A smaller depression, the Tajo abyssal plain (15,000 km2), receives sediments from the Tajo River (Portugal) through an underwater canyon. In addition, to the south (to the west of the sources of sedimentary materials of Gibraltar, Guadiana and Guadalquivir) is the abyssal plain of Horseshoe (14 thousand km2).

canary basin (Monaco Basin) is located south of the Azores uplift (seamount belt), stretching in the direction of ESE. This basin is largely occupied by the Madeira abyssal plain, and it is now established that it includes a sector formerly belonging to the Canarian abyssal plain. A smaller depression, the Sein abyssal plain (39,000 km1), located east of the Senya bank, is separated from this basin and, apparently, is fed from it. Wüst distinguishes the North Canary and South Canary basins, but this distinction is not very clear. Most of the Canary Basin is made up of the wide continental foot of Morocco and the volcanic plateaus of the Canary Islands and the island of Madeira.

Cape Verde Basin (North African Trench, Chan Basin, Moseli Basin). The abyssal plain of Cape Verde is almost not separated from the abyssal plain of Madeyera (together 530 thousand km2, the border is the belt of abyssal hills), continues a vast belt of abyssal plains with a length of about 1000 km, following along the outer border of West Africa, turns approximately to the west and southwest from the Cape Verde Islands. South of these islands is the abyssal plain of the Gambia.

Basin of Sierra Leone , The aforementioned belt of abyssal plains skirts the western coast of Africa, separated by an aseismic uplift and abyssal hills from the underwater highlands of Sierra Leone, which in turn is separated from the mainland foot by the abyssal plain of Sierra Leone. However, the width of the continental foot
decreases to about 500 km.

Guinea Basin (West African Trench). This basin is a continuation of the same belt of abyssal plains in the Gulf of Guinea, but contains an elongated depression, the Guinea abyssal plain, which is abundantly fed by the largest river in West Africa, the Niger, and the Niger abyssal fan.

Angolan Basin (Buchanan depression). South of the Guinean volcanic ridge (Fernando Po Islands, etc.), there is an extensive depression of the Angolan abyssal plain (140 thousand km4), fed at the northern end of the Congo River, the abyssal cone of the Congo River and the Congo Canyon, the largest underwater canyon in Eastern Atlantic.

Cape Basin (Valvis basin). The Whale Ridge, which runs northeast-southwest parallel to the Guinean Ridge but, in contrast, is currently aseismic and non-volcanic, is followed by the Cape Abyssal Plain, fed by the Orange River.

Basin Agulhas . In the complex section of the continental borderland (Agulyas Bank) and the normal quasi-cratonic crust, the main depression is the Agulhas abyssal plain (to the east of latitude 20°, located in the Indian Ocean).

Raised and ridges

The Mid-Atlantic Ridge is the main topographic feature on the floor of the Atlantic Ocean and divides the main part of the ocean into two large basins. Secondary ridges or uplifts divide these basins into basins. However, the ridges rarely form a continuous chain, so bottom water from Antarctica can move north along the western borders of the Atlantic Ocean into the North American Basin and east and then south into the eastern basin through the Romanche Trench (or Romanche Gorge). The Romansh trench corresponds to a large latitudinal fault zone. Another significant fault zone located to the north of the above is known as the Guinean fault zone. Another fault zone occurs at about 50-53°N. sh. This area, surveyed during the laying of the transatlantic cable, is called the Telegraph Plateau. The transverse ridges were mostly discovered and named by the Meteor expedition. The Atlantic Ocean has the following uplifts and ridges.

Western Atlantic

Greenland-Icelandic uplift - a distinct threshold with a depth of less than 1000 m, separates the Greenland Sea from the Irminger Sea.

Labrador uplift is not clearly expressed and extends from the Flemish Bank towards the northeast. It is cut through by a mid-ocean canyon. It is believed that continental rocks are not found outside the bank.

Southeast Newfoundland Rise extends southeast from the Great Newfoundland Bank. Like the previous uplift, it is indistinct and is also cut through by a mid-ocean canyon.

Antilles, or Caribbean arc (ridge) - a typical double island arc. Barbados is an outer non-volcanic ridge. Numerous Windward Islands are of volcanic origin.

Rise Steam located between the northeastern part of Brazil and the Mid-Atlantic Ridge and is not a barrier to deep currents. It is partly a "mound" of sedimentary material from underwater fans of the Amazon and others. To the southeast is a small volcanic ridge with mature, deeply dissected volcanic formations of Fernando de Noronha and Rocas.

Rise of Trindade - a distinctly expressed volcanic ridge, stretching east from the Brazilian province of Espiritu Saito for 1200 km. It reaches its highest height on the island of Trindade and the reefs of Martin-Vas. It partially forms the boundary between the North Brazilian and South Brazilian basins, but east of
the island of Trindade has no barriers at all.

Rio Grande Underwater Rise (sometimes called the Bromley Plateau) is a massive aseismic ridge stretching east from the Brazilian province of Rio Grande do Sul for 1500 km. It is slightly short of the edge of the Mid-Atlantic Ridge. On the mainland side, it is partly separated from the broad plateau (the mainland borderland) located southeast of São Paulo, and consists of continental rocks, probably broken off from the shelf as a result of stock tectonics.

Falkland Plateau stretched for 1800 km east of the Argentine shelf. Stille called it a structural spur of the borderland, composed of typical mainland rocks (demon and others exposed in the Falkland Islands). The plateau is partially split by faults going to the Malvinskaya Basin, south of the Falkland Islands.

Uplift of South Georgia - short, stretching to the northeast from the island of South Georgia.

Arc, or ridge, Scotia (South Antilles arc, South Sandwich Range) - a typical island arc of non-volcanic origin, located in the area of ​​South Georgia Island and the South Orkney Islands, in a zone of volcanic activity near the angle of maximum bend of the South Shetland Islands. It is assumed that latitudinal horizontal faults run along the northern and southern edges of the arc, as in the Antilles arc in the Caribbean Sea. Thus, these two arcs are almost identical in structure.

East Atlantic

Faroese Icelandic threshold an aseismic ridge that forms a massive barrier in the North Atlantic. The Faroe Islands are composed of mature accumulations of volcanic origin. Volcanoes in this area have long lost their activity.

Wyville Thomson Threshold (Faroe - Shetland Range) - an aseismic barrier similar to the Icelandic-Faroe Range. Overlaps the Icelandic-Faroe Range in the south and adjoins it to the west of the Faroe Islands. In the south, the sill is divided by the fault basin of the Faroe-Shetland Strait.

Banka, or Plateau, Rockall extends southwest from the Wyville Thomson Sill and is topped by the isolated Rockall igneous stock. It also belongs to aseismic
ridges.

Bank Porcupine located near the mainland to the south-west of Ireland and is a fragment of the mainland borderland.

Biscay uplift extends west from Galicia (Spain) and essentially joins the eastern edge of the Mid-Atlantic Ridge; it is crossed by a number of deep-water channels, along which turbidity currents move in a southerly direction.

Azores uplift extends east from the Azores Plateau, which is an unusual domed section of the Mid-Atlantic Ridge and resembles the young Icelandic Plateau. The uplift is a volcanic ridge formed by a continuous chain of seamounts. continuing to the Seine Bank and almost to the Strait of Gibraltar

Madeira Range is a short volcanic range located southwest of Portugal.

Rise of the Canary Islands - a wide volcanic plateau, the geological structure of the basement of which is unknown, located parallel to the coast North Africa and more like a mainland borderland.

Cape Verde Plateau is a similar to the previous, but wider plateau (or uplift), classified by Heezen as an aseismic ridge, stretching west from the Senegalese coast of Africa for about 800 km. It is characterized by mature volcanoes as well as rocks of Tertiary age and is, at least in part, a mainland borderland.

Upland Sierra Leone - a weakly pronounced uplift of the abyssal hills, stretching southwest from Freetown and reaching the Mid-Atlantic Ridge northeast of the island of São Paulo. It is crossed by several significant latitudinal fault zones, in particular the Guinean fault zone.

Liberia uplift - a small but peculiar uplift of a mid-ocean character, apparently dissected in the north and south by latitudinal faults. It partially separates the Sierra Leone Basin from the Guinea Basin.

Guinea Ridge - a significant volcanic ridge, which is a continuation of the Cameroon volcanic belt. The Guinean Ridge passes through the island of Fernando Po and other volcanic islands in the Gulf of Guinea Somewhat south of the equator, it approaches the northeastern part of the Mid-Atlantic Ridge.

whale range (Walvis) - the most significant transverse ridge in the South Atlantic, connecting Southwest Africa with the Mid-Atlantic Ridge. It has ledges of more than 1000 m, but at the southwestern end it drops significantly in the direction
Tristan da Cunha Islands of the Gough Islands.

Cape uplift - the southernmost transverse landform, partly a volcanic ridge, stretching from the Cape of Good Hope to the southwest in the direction of Bouvet Island. It has a smooth relief with separate seamounts.

Hydrological regime temperature and salinity

Of all the world's oceans, the Atlantic Ocean has the most data. Detailed maps of the temperature and salinity of the waters of the Atlantic Ocean have been compiled.
There is also more data on chemical and biological characteristics in the Atlantic Ocean than in other oceans. It is also possible to calculate water and heat budgets, such as evaporation and heat transfer between the ocean and the atmosphere.

temperature and salinity. The Atlantic Ocean is the warmest and most saline of all oceans. It receives, undoubtedly, the largest part of the river flow. The average potential temperature and salinity are 3.73°C and 34.90 ppm, respectively. The temperature amplitude of the surface layer depends mainly on the latitude and the system of currents, its average value is 16 9 ° C (between 90 ° N and 80 ° S). The salinity of the surface layer is affected by the amount of precipitation, the amount of fresh water runoff from the continents and the presence of currents. Its average value is 34.87 ppm (between 90°N and 80°S). Below the surface layer, the governing factors for both parameters are advection and turbulent diffusion. There are seasonal changes in temperature and salinity of the surface layer, extending to a depth of approximately 200 m. These changes are most pronounced near the coasts with a continental climate.

The largest annual temperature range of the surface layer in the open ocean is 7°C (between 40-50°N and 30-40°S). (This is an average zonal value; fluctuations in the Northwest Atlantic can reach 15 ° C.) The temperature amplitude of the surface layer in the equatorial and polar regions is less than 2 ° C. In coastal regions, the temperature of the surface layer during the year can vary by 25 ° C. On the annual fluctuation of the salinity of the surface layer is influenced by various factors: melting and formation sea ​​ice(polar regions), seasonal changes in evaporation rate and precipitation (Caribbean). In coastal areas affected by high spring runoff, such as off the northeast coast of the United States, salinity fluctuations can be as high as 3 ppm; however, in the open ocean, the salinity of the surface layer changes to a much lesser extent, rarely by more than 1 ind.

The Atlantic Ocean is the most studied and mastered by people of all the oceans. According to one hypothesis, it got its name from the name of the titan Atlanta (according to Greek mythology, holding the vault of heaven on his shoulders). V different time it was called differently: "The Sea behind the Pillars of Hercules", "Atlantic", "Western Ocean", "Sea of ​​Darkness", etc. The name "Atlantic Ocean" first appeared in 1507 on a map by Wald-Semüller, since then the name has established itself in geography.

The geographical position of the ocean

The Atlantic Ocean is the second largest ocean on the planet. It covers an area of ​​92 million km. The Atlantic Ocean washes the shores of five continents.

The boundaries of the Atlantic Ocean are North America and Eurasia in the northern part, and South America, Africa and Antarctica in the south.

The Atlantic separates the Old World from the New.

The Atlantic Ocean is crossed by the equator and the prime meridian (see Fig. 1). Its length is 13 thousand km. The ocean is wide (maximum width - 6700 km) in the northern and southern parts, narrowing in equatorial latitudes to 2900 km. In the north it communicates with the Arctic Ocean, and in the south it is widely connected with the Pacific and Indian Oceans.

Rice. 1. Physical map of the Atlantic Ocean

The Atlantic Ocean is the second largest ocean in the world. The coastline of the ocean in the northern hemisphere is heavily dissected by numerous peninsulas and bays. There are many islands, inland and marginal seas near the continents. The Atlantic consists of 13 seas, which occupy 11% of its area (see Fig. 2).

Remember the names of the largest of them.

Caribbean - 1

Gulf of Mexico -2

Sargasso Sea - 3

Baltic Sea - 4

Bay of Biscay - 5

Mediterranean Sea - 6

Black Sea - 7

Gulf of Guinea - 8

Weddell Sea - 9

Rice. 2. Seas of the Atlantic Ocean

The relief of the bottom of the Atlantic Ocean

The Atlantic Ocean is younger than the Pacific, it was formed in the Mesozoic era, after the collapse of the Gondwana mainland. Its bottom is sections of several lithospheric plates. In the center of the Atlantic Ocean, a huge Mid-Atlantic Ridge stretches from north to south, broken by many transverse faults.

The relative height of the ridge is about 2 km. Transverse faults divide it into separate segments. In the axial part of the ridge there is a giant rift valley 6 to 30 km wide and up to 2 km deep. Both underwater active volcanoes and volcanoes of Iceland and the Azores are confined to the rift and faults of the Mid-Atlantic Ridge. On both sides of the ridge there are basins with a relatively flat bottom, separated by elevated uplifts. The shelf area in the Atlantic Ocean is larger than in the Pacific.

It is here, in the central parts of the Mid-Atlantic Ridge, from the depths of the mantle that a young Earth's crust and gradually diverges to the east and west, slowly expanding the ocean. On a ledge of the Mid-Atlantic Ridge is the island of Iceland - one of the most beautiful places on Earth (see Fig. 3).

Rice. 3. Iceland

There are extensive ocean trenches in the eastern and western parts of the ocean, and two small deep-sea troughs are located off the western coasts - the deepest parts of the ocean (see Fig. 4).

Rice. 4. The relief of the bottom of the Atlantic Ocean

climate of the atlantic ocean

The Atlantic Ocean is located in almost all climatic zones, except for one (identify its name on the map). That's right, this is the Arctic climate zone.

The zonality of water masses in the ocean is complicated by the influence of land and sea currents. This is manifested primarily in the temperature distribution of surface waters. In many areas of the ocean, the isotherms near the coast deviate sharply from the latitudinal direction.

The northern half of the ocean is warmer than the southern one, the temperature difference reaches 6°С. The average surface water temperature (16.5°C) is slightly lower than in the Pacific Ocean.

The cooling effect is exerted by the waters and ices of the Arctic and Antarctic. The salinity of surface waters in the Atlantic Ocean is high. One of the reasons for increased salinity is that a significant part of the moisture evaporating from the water area does not return to the ocean again, but is transferred to neighboring continents (due to the relative narrowness of the ocean).

Many large rivers flow into the Atlantic Ocean and its seas: the Amazon, Congo, Mississippi, Nile, Danube, La Plata, etc. They carry huge masses of fresh water, suspended material and pollutants into the ocean. In desalinated bays and seas of subpolar and temperate latitudes, ice forms near the western shores of the ocean in winter. Numerous icebergs and floating sea ice hinder navigation in the North Atlantic Ocean.

In the subtropical and tropical latitudes the trade winds blow, but in the Atlantic the winds of the West are much more powerful and furious. They are especially strong in the temperate latitudes of the Southern Hemisphere.

In the western part of the Atlantic, the strongest storms and hurricanes regularly arise, unleashing their fury on the coast. There are 10-20 of them per season. Weather reports sometimes resemble military reports.

currents of the atlantic ocean

The prevailing winds form the main currents in the oceans. But the Atlantic Ocean is strongly elongated from north to south, and therefore its main currents are elongated along the ocean - in the meridional direction (see Fig. 5).

In the Atlantic, as in the Pacific, two rings of surface currents form.

Follow the maps of the atlas and learn how to easily find the next currents of the Atlantic Ocean.

In the northern hemisphere, the North Equatorial Current, the Gulf Stream, the North Atlantic and Canary Currents form the movement of waters in a clockwise direction.

In the southern hemisphere, the South Trade Winds, the Brazilian, the West Winds and the Benguela move the waters counterclockwise.

Due to the significant length of the Atlantic Ocean from north to south, meridional water flows are more developed in it than latitudinal ones.

Rice. 5. Map of the currents of the Atlantic Ocean

Organic World of the Atlantic

The Atlantic Ocean is poorer in species in the composition of flora and fauna than the Pacific. One of the reasons for this is its relative geological youth and a noticeable cooling in the Quaternary period during the glaciation of the northern hemisphere.

However, in quantitative terms, the ocean is rich in organisms - it is the most productive per unit area.

This is primarily due to the wide development of shelves and shallow banks, which are inhabited by many demersal and bottom fish (cod, flounder, perch, etc.).

Exploration of the Atlantic Ocean

The Atlantic Ocean from ancient times began to be mastered by people. And now it plays a huge role in the life of mankind: a dense network of the most important transport routes stretches through it, connecting Europe with America and the countries of the Persian Gulf.

Oil is produced on the shelf of the North Sea and the Gulf of Mexico, and reserves of iron-manganese nodules have been discovered in the southern part of the ocean.

In the Atlantic Ocean are the main fishing areas and the most popular resorts in the world.

The biological resources of the ocean have long been intensively used. However, due to the overfishing of a number of valuable commercial fish species, in last years The Atlantic is inferior to the Pacific Ocean in terms of fish and seafood production.

Intensive human economic activity in the waters of the Atlantic Ocean and its seas causes a noticeable deterioration natural environment- both in the ocean (water and air pollution, a decrease in the stocks of commercial fish species), and on the coasts.

In order to prevent further and reduce the existing pollution of the natural environment of the Atlantic Ocean, scientific recommendations are being developed and international agreements are being concluded on the rational use of ocean resources.

Bibliography

MainI am

1. Geography. Earth and people. Grade 7: Textbook for general education. uch. / A.P. Kuznetsov, L.E. Savelyeva, V.P. Dronov, "Spheres" series. – M.: Enlightenment, 2011.

2. Geography. Earth and people. Grade 7: atlas, series "Spheres".

Additional

1. N.A. Maksimov. Behind the pages of a geography textbook. – M.: Enlightenment.

2. Russian Geographical Society ().

3. Study guide for geography ().

4. Geographical directory ().

ATLANTIC OCEAN (Latin name Mare Atlanticum, Greek? τλαντ?ς - denoted 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 essay. 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 Island to Cape Brewster, through the Danish Strait to Cape Reidinupur on the island of Iceland, along its coast to Cape Gerpir (Terpier), then to the Faroe Islands, then to the Shetland Islands and along 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 the line passing 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 of 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 southern part of the Atlantic Ocean is sometimes called the Atlantic sector of the Southern Ocean, drawing the boundary along the subantarctic convergence zone (approximately 40 ° south latitude). Some papers propose the division of the Atlantic Ocean into the North and South Atlantic Oceans, but it is more common 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; the 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 (Puerto Rico Trench). The most easily accessible for development shelf zone of the ocean (with depths up to 200 m) occupies about 5% of its area (or 8.6%, if we take into account the 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 map.

Seas. In the basin of the Atlantic Ocean there are numerous seas, which are divided into: internal - Baltic, Azov, Black, Marmara and Mediterranean (in the latter, in turn, the seas are distinguished: Adriatic, Alboran, Balearic, Ionian, Cypriot, Ligurian, Tyrrhenian, Aegean) ; interisland - Irish and inland seas of the western coast of Scotland; marginal - Labrador, Northern, Sargasso, Caribbean, Scotia (Scotia), Weddell, Lazareva, the western part of Riiser-Larsen (see separate articles about the seas). The largest bays of the ocean: Biscay, Bristol, Guinean, Mexican, Maine, St. Lawrence.

Islands. Unlike other oceans, there are few seamounts, guyots and coral reefs in the Atlantic Ocean, and there are no coastal reefs. The total area of ​​the islands of the Atlantic Ocean is about 1070 thousand km2. 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 (Land of Fire, Oste, Navarino ), Marajo, Sicily, Sardinia, Lesser Antilles, Falkland (Malvinas), Bahamas, etc. Small islands are found in the open ocean: Azores, Sao Paulo, Ascension, Tristan da Cunha, Bouvet (on the Mid-Atlantic Ridge) and others

coast. The coastline in the northern part of the Atlantic Ocean is strongly indented (see also the article Coast), almost all major inland seas and bays are located here, in the southern part of the Atlantic Ocean the coasts are slightly indented. The coasts of Greenland, Iceland and the coast of Norway are predominantly tectonic-glacial dissection of the fjord and fiard types. To the south, in Belgium, they give way to sandy shallow shores. The coast of Flanders is mainly of artificial origin (coastal dams, polders, canals, etc.). The coasts of the island of Great Britain and the island of Ireland are abrasion-bay, high limestone cliffs alternate with sandy beaches and mud sludge. The Cherbourg Peninsula has rocky shores, sandy and gravel beaches. The northern coast of the Iberian Peninsula is composed of rocks, to the south, off the coast of Portugal, sandy beaches predominate, often fencing off lagoons. Sandy beaches also border the shores of Western Sahara and Mauritania. To the south of Cape Zeleny 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 coast with a significant number of spits and lagoons. In southwestern Africa - accumulative, less often abrasion-bay shores with extensive sandy beaches. The coasts of southern Africa of the abrasion-bay type are composed of solid crystalline rocks. The coasts of Arctic Canada are abrasive, with high cliffs, glacial deposits and limestones. In eastern Canada and the northern part of the Gulf of St. Lawrence, there are intensely eroded limestone and sandstone cliffs. In the west and south of the Gulf of St. Lawrence - wide beaches. On the shores of the Canadian provinces of Nova Scotia, Quebec, Newfoundland, there are outcrops of solid crystalline rocks. Approximately from 40 ° north latitude to Cape Canaveral in the USA (Florida) - alternation of leveled accumulative and abrasion types of coasts, composed of loose rocks. The Gulf Coast is low-lying, bordered by mangroves in Florida, sand barriers in Texas, and delta shores in Louisiana. On the Yucatan Peninsula - cemented beach sediments, to the west of the peninsula - an alluvial-marine plain with coastal ridges. On the coast of the Caribbean Sea, abrasion and accumulative areas alternate with mangrove swamps, alongshore barriers and sandy beaches. To the south of 10° north latitude, accumulative banks are widespread, composed of material carried from the mouth of the Amazon River and other rivers. In the northeast of Brazil - a sandy coast with mangroves, interrupted by river estuaries. From Cape Kalkanyar to 30 ° south latitude - a high, deep coast of an abrasion type. To the south (off the coast of Uruguay) there is an abrasion-type coast composed of clays, loess and sand and gravel deposits. In Patagonia, the coasts are represented by high (up to 200 m) cliffs with loose deposits. 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 major geomorphological provinces are distinguished: the underwater margin of the continents (shelf and continental slope), the ocean floor (deep-water 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 passes on average at depths of 100-200 m, its position can vary from 40-70 m (near Cape Hatteras and the Florida Peninsula) to 300-350 m (Weddell Cape). Shelf width from 15-30 km (northeast of Brazil, Iberian Peninsula) to several hundred km (North Sea, Gulf of Mexico, Newfoundland Bank). In high latitudes, the shelf relief is complex and bears traces of glacial influence. Numerous uplifts (banks) are separated by longitudinal and transverse valleys or trenches. Off the coast of Antarctica on the shelf are ice shelves. At low latitudes, the shelf surface is more leveled, especially in the areas where terrigenous material is carried out 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° (regions of Gibraltar, the Shetland Islands, parts of the coast of Africa, etc.) to 15-20° off the coast of France and the 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 area of ​​the Bahamas and the Puerto Rico Trench. Active margins are characterized by high seismicity. The surface of the slope is dissected in places by steps, ledges and terraces of tectonic and accumulative origin and longitudinal canyons. At the foot of the continental slope, gently sloping hills up to 300 m high and shallow underwater valleys are often located.

In the middle part of the bottom of the Atlantic Ocean is the largest mountain system of the Mid-Atlantic Ridge. It extends from the island of Iceland to the island of Bouvet for 18,000 km. The width of the ridge is from several hundred to 1000 km. The crest of 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-sea basins separated by bottom uplifts. In the western part of the Atlantic Ocean, 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 abyssal plains of Som, Hatteras and Nares; Guiana (4500-5000 m) with the plains of Demerara and Ceara; Brazilian basin (5000-5500 m) with the abyssal plain of Pernambuco; Argentine (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), Zeleniy Cape (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. To the south is the African-Antarctic Basin with the abyssal Weddell Plain. The bottoms of deep-water basins at the foot of the Mid-Atlantic Ridge are occupied by the zone of abyssal hills. The basins are separated by the Bermuda, Rio Grande, Rockall, Sierra Leone, and other uplifts, and by the Kitovy, Newfoundland, and other ridges.

Seamounts (isolated conical elevations 1000 m or more high) on the bottom of the Atlantic Ocean are concentrated mainly in the zone of the Mid-Atlantic Ridge. In the deep waters, large groups of seamounts occur north of Bermuda, in the Gibraltar sector, off the northeastern salient of South America, in the Gulf of Guinea, and west of South Africa.

The Puerto Rico deep-sea trenches, Cayman (7090 m), South Sandwich Trench (8264 m) are located near the island arcs. The Romansh Trench (7856 m) is a large fault. The steepness of the slopes of deep-sea trenches is from 11° to 20°. The bottom of the troughs is flat, leveled by accumulation processes.

Geological structure. The Atlantic Ocean arose as a result of the breakup of the Late Paleozoic supercontinent Pangea during the Jurassic. It is characterized by a sharp predominance of passive margins. The Atlantic Ocean borders the adjacent continents along transform faults south of Newfoundland, along the northern coast of the Gulf of Guinea, along the Falkland Submarine Plateau and the Agulhas Plateau in the southern part of the ocean. Active margins are observed in separate areas (in the region of the Lesser Antilles arc and the arc of the South Sandwich Islands), where subduction with underthrust (subduction) of the Atlantic Ocean crust occurs. The Gibraltar subduction zone, limited in length, has been identified in the Gulf of Cadiz.

In the Mid-Atlantic Ridge, the bottom is being pushed apart (spreading) and oceanic crust is forming at a rate of up to 2 cm per year. High seismic and volcanic activity is characteristic. To the north, paleospreading ridges branch off from the Mid-Atlantic Ridge into the Labrador Sea and the Bay of Biscay. In the axial part of the ridge, a rift valley is pronounced, which is absent in the extreme south and in most of the Reykjanes ridge. Within its limits - volcanic uplifts, frozen lava lakes, basaltic lava flows in the form of pipes (pillow-basalts). In the Central Atlantic, fields of metal-bearing hydrotherms have been found, many of which form hydrothermal structures 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 scree and landslides, consisting of blocks and crushed stone of oceanic crust rocks (basalts, gabbro, 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 covered by a sedimentary cover, the thickness of which increases towards the continental foothills up to 10-13 km due to the appearance of more ancient horizons in the section and the supply of detrital material from land. In the same direction, the age of the oceanic crust increases, reaching the Early Cretaceous (Middle Jurassic north of Florida). 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 per 1700 km). The largest transform faults (Vima, São Paulo, Romansh, etc.) are accompanied by deep incisions (troughs) on the ocean floor. They expose the entire section of the oceanic crust and partially the upper mantle; protrusions (cold intrusions) of serpentinized peridotites are widely developed, forming ridges elongated along the strike of the faults. Many transform faults are transoceanic or main (demarcation) faults. In the Atlantic Ocean, there are so-called intraplate uplifts, represented by underwater plateaus, aseismic ridges and islands. They possess oceanic crust increased power and are mainly of volcanic origin. Many of them were formed as a result of the action of mantle jets (plumes); some originated 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, Sierra and Sierra Leone Twin Uplifts, Rio Grande and Whale Range, Bermuda Uplift, Cameroon group of volcanoes, etc. In the Atlantic Ocean there are intra-plate uplifts of non-volcanic nature, among which is the underwater Rockall Plateau, separated from the British Isles by the trough of the same name. The plateau is a microcontinent that separated from Greenland in the Paleocene. Another micro-continent that also broke away from Greenland is the Hebrides in northern Scotland. The underwater marginal plateaus off the coast of Newfoundland (Great Newfoundland, Flemish Cap) and off the coast of Portugal (Iberian) separated 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. At the end of the Jurassic - the beginning of the Cretaceous, the Antarctic segment began to open up. In the Early Cretaceous, spreading was experienced by the Southern segment in the South Atlantic and the Newfoundland-Iberian segment in the North Atlantic. The 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 Atlantics united in the middle of the Cretaceous - Eocene during the formation of the Equatorial segment.

Bottom sediments . The thickness of modern bottom sediments ranges from several meters in the zone of the crest of the Mid-Atlantic Ridge to 5-10 km in the zones of transverse faults (for example, in the Romansh 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 foraminifers, coccolithophorids). Their composition varies from coarse sands (at depths up to 200 m) to silts. At depths greater than 4500-4700 m, calcareous oozes are replaced by polygenic and siliceous planktonic sediments. The former occupy about 28.5% of the area of ​​the ocean floor, lining the bottoms of the basins, and are represented by red deep-sea 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 area, of which diatom silts (formed by diatom skeletons) are the most common. They are common off the coast of Antarctica and on the shelf of Southwest Africa. Radiolarian muds (formed by radiolarian skeletons) are found mainly in the Angolan Basin. Along the coasts of the ocean, on the shelf and partly on the continental slopes, terrigenous sediments of various compositions (gravel-pebble, sandy, clayey, etc.) are developed. The composition and thickness of terrigenous sediments are determined by the bottom relief, the activity of solid material supply from land, and the mechanism of their transfer. Glacial precipitation carried by icebergs is distributed along the coast of Antarctica, Greenland, Newfoundland, and the Labrador Peninsula; composed of weakly sorted clastic material with boulders included, mostly in the south of the Atlantic Ocean. Sediments (from coarse sand to silt) formed from pteropod shells are often found in the equatorial part. Coral sediments (coral breccias, pebbles, sands and silts) are localized in the Gulf of Mexico, the Caribbean Sea and off the northeast coast of Brazil; their maximum depth is 3500 meters. Volcanic sediments are developed near the volcanic islands (Iceland, Azores, Canaries, Cape Verde, etc.) and are represented by fragments of volcanic rocks, slag, pumice, and volcanic ash. Modern chemogenic sediments are found on the Great Bahama Bank, in the Florida-Bahamas, Antilles regions (chemogenic and chemogenic-biogenic carbonates). In the basins of the North American, Brazilian, and Green Cape, ferromanganese nodules are found; 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 great length of the Atlantic Ocean, its waters are located in almost all natural climatic zones- from subarctic in the north to antarctic in the south. From the north and south, the ocean is widely open to the influence 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, while temperatures of -32.3°C have been recorded in the southern Weddell Sea. 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 - 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 maintains stable easterly winds (trade winds) in tropical and equatorial latitudes, and strong westerly winds in temperate latitudes, which have received the name "roaring forties" from navigators. Strong winds are also characteristic of the Bay of Biscay. In the equatorial region, the interaction of the northern and southern baric systems leads to frequent tropical cyclones (tropical hurricanes), which are most active 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 is frequent and heavy clouds are observed. Thus, at the equator over 2000 mm of precipitation falls annually, 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 High, 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 flow into the World Ocean). The largest rivers (with annual expense 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 fresh water balance of 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 underground runoff (21 thousand km 3 / year) and melting of ice and icebergs in the Arctic and Antarctic (about 3 thousand km 3 / year). The deficit in the water balance is replenished by the inflow of water, mainly from the Pacific Ocean, through the Drake Strait with the course of the West Winds, 3470 thousand km 3 / year enters, and only 210 thousand km 3 / year goes from the Atlantic Ocean to the Pacific Ocean. From the Arctic Ocean, through numerous straits, 260 thousand km 3 / year enters the Atlantic Ocean and 225 thousand km 3 / year of Atlantic water flows back into the Arctic Ocean. The water balance with the Indian Ocean is negative, 4976 thousand km 3 / year is carried into the Indian Ocean with the course of the West 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 the ocean waters as a whole is 4.04 °C, and that of surface waters is 15.45 °C. The distribution of water temperature on the surface is asymmetric with respect 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 Northern Hemisphere, the warmest waters of the open part of the ocean (thermal equator) are between 5 and 10 ° north latitude, that is, they are shifted north of the geographic equator. Features of large-scale circulation of waters lead to the fact that the temperature of water on the surface near the western coasts of the ocean is approximately 5 ° C higher than that of the eastern ones. The warmest water temperature (28-29 ° C) on the surface in the Caribbean Sea and the Gulf of Mexico in August, the lowest - off the coast of Greenland, Baffin Island, the Labrador Peninsula and Antarctica, south of 60 °, where even in summer the water temperature does not rise above 0 °C. The water temperature in the layer of the main thermocline (600-900 m) is about 8-9 °C, deeper, in intermediate waters, it drops to an average of 5.5 °C (1.5-2 °C in Antarctic intermediate waters). In deep waters, the water temperature is on average 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‰, and that of surface waters is 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 inflow with precipitation, the lowest (6-20‰) in the estuarine sections of large rivers flowing into the ocean. From the 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 minimum of salinity is observed at depths of 600-800 m. The waters of the northern part of the 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, bottom waters occupying the deepest depressions of the ocean, respectively, 34.7-34.8‰ and 1.6 °C.

Density. The density of water depends on temperature and salinity, and for the Atlantic Ocean, temperature is of greater importance in the formation of the water density field. Waters with the lowest density are located in the equatorial and tropical zones with high water temperature and a strong influence of the flow 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 northern part of the Atlantic Ocean, first-year ice forms mainly in the inland seas of temperate latitudes; multi-year ice is carried out of the Arctic Ocean. The boundary of the distribution of the ice cover in the northern part of the Atlantic Ocean varies significantly; in winter, pack ice can reach 50-55 ° north latitude in different years. There is no ice in summer. The boundary of Antarctic multi-year ice in winter runs at a distance of 1600-1800 km from the coast (approximately 55 ° south latitude), in summer (in February - March) ice is found 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. total weight icebergs coming from the Antarctic glaciers are estimated at 1.6·10 12 tons per year, their main source is the Filchner Ice Shelf in the Weddell Sea. Icebergs with a total mass of 0.2-0.3·10 12 tons per year enter the Atlantic Ocean from the glaciers of the Arctic, mainly from the Jakobshavn glacier (near Disko Island off the western coast of Greenland). The average life expectancy of Arctic icebergs is about 4 years, Antarctic icebergs are somewhat longer. The iceberg distribution limit in the northern part of the ocean is 40° north latitude, but in some cases they have been observed up to 31° north latitude. In the southern part, the boundary passes at 40° S latitude in the central part of the ocean and at 35° S latitude on the western and eastern periphery.

currents. The circulation of the waters of the Atlantic Ocean is subdivided into 8 quasi-stationary oceanic circulations, located almost symmetrically with respect to the equator. From low to high latitudes in the Northern and Southern Hemispheres there are tropical anticyclonic, tropical cyclonic, subtropical anticyclonic, subpolar cyclonic oceanic gyres. Their boundaries, as a rule, make up the main ocean currents. The Gulf Stream flows off the Florida peninsula. Absorbing the waters of the warm Antilles Current and the Florida Current, the Gulf Stream heads northeast and at high latitudes is divided into several branches; the most significant of them is the Irminger Current, which carries warm waters to the Davis Strait, the North Atlantic Current, the Norwegian Current, going to the Norwegian Sea and further to the northeast, along the coast of the Scandinavian Peninsula. To meet them, the cold Labrador Current emerges from the Davis Strait, the waters of which can be traced off the coast of America almost to 30 ° north latitude. From the Danish Strait, the cold East Greenland Current flows into the ocean. In the low latitudes of the Atlantic Ocean, warm Northern trade wind currents and Southern trade wind currents are directed from east to west, between them, at about 10 ° north latitude, from west to east, there is an Intertrade countercurrent, which is active mainly in the summer in the Northern Hemisphere. The Brazilian Current separates from the South Trade Wind Currents, which runs from the equator to 40 ° south latitude along the coast of America. The northern branch of the South Trade Winds forms the Guiana Current, which is directed from south to northwest until it joins the waters of the North Trade Winds. Off the coast of Africa, from 20 ° north latitude to the equator, the warm Guinea current passes, in the summer the Inter-trade countercurrent connects with it. In the southern part, the Atlantic Ocean is crossed by the cold West Wind Current (Antarctic Circumpolar Current), which enters the Atlantic Ocean through the Drake Passage, descends to 40 ° south latitude and exits into the Indian Ocean south of Africa. 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, separate from it. 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 Northern trade winds.

Deep water circulation. The deep circulation and structure of the waters of the Atlantic Ocean are formed as a result of a change in their density during cooling of waters or in zones of mixing of waters of different origin, where density increases as a result of mixing of waters with different salinities and temperatures. 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 the 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. Deep waters are formed 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‰. The waters formed in the high northern latitudes move from north to south in the 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, which was 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 part of the ocean, a few centimeters in the Black Sea, 18 meters in the Bay of Fundy (the northern part of the Gulf of Maine in North America) is the highest in the world. The height of wind waves depends on the speed, exposure time and wind acceleration, during strong storms it can reach 17-18 m. Quite rarely (once every 15-20 years) waves of 22-26 m were observed.

Flora and fauna. The great extent of the Atlantic Ocean, the diversity of climatic conditions, a significant inflow of fresh water and large upwellings provide a variety of habitat conditions. In total, about 200 thousand species of plants and animals live in the ocean (of which about 15,000 species of fish, about 600 species of cephalopods, about 100 species of whales and pinnipeds). Life is distributed very unevenly in the ocean. There are three main types of zonality in the distribution of life in the ocean: latitudinal or climatic, vertical and circumcontinental zonality. 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 to high latitudes.

Planktonic organisms (phytoplankton and zooplankton) are the basis of the food chain in the ocean, most of them live in the upper zone of the ocean, where light penetrates. The highest plankton biomass is in high and temperate latitudes during the spring-summer bloom (1-4 g/m3). During the year, biomass can change by 10-100 times. The main types of phytoplankton are diatoms, zooplankton are copepods and euphausids (up to 90%), as well as chaetognaths, hydromedusae, ctenophores (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 Gulf of Mexico and Guinea. Phytoplankton is represented mainly by coccolithins and peridineans, the latter can develop in coastal waters in huge quantities, causing the catastrophic phenomenon of the "red tide". Low latitude zooplankton is represented by copepods, chaetognaths, hyperids, hydromedusae, siphonophores, and other species. There are no clearly pronounced dominant zooplankton species in low latitudes.

Benthos is represented by large algae (macrophytes), which mostly grow at the bottom of the shelf zone, down 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 anchoring to the bottom, the absence or moderate speeds of bottom currents, etc. In the high latitudes of the Atlantic Ocean, the main part of phytobenthos is kelp and red algae. In the temperate zone of the northern part of the Atlantic Ocean, along the American and European coasts, there are brown algae (fucus and ascophyllum), kelp, desmarestia and red algae (furcellaria, ahnfeltia, etc.). Zostera is common on soft soils. Brown algae predominate in the temperate and cold zones of the South Atlantic Ocean. In the tropical zone in the littoral, 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 species of Sargassum algae) form clusters on the surface in the form of ribbons from 100 m to several kilometers long.

Most of the nekton biomass (actively swimming animals - fish, cephalopods and mammals) is fish. The largest number of species (75%) lives in the shelf zone; with depth and with distance from the coast, the number of species decreases. The cold and temperate zones are characterized by: fish - various types of cod, haddock, saithe, herring, flounder, catfish, conger eel, etc., herring and polar sharks; from mammals - pinnipeds (harp seal, hooded seal, etc.), various types of cetaceans (whales, sperm whales, killer whales, pilot whales, bottlenose, etc.).

There is a great similarity between the faunas of temperate and high latitudes of both hemispheres. At least 100 species of animals are bipolar, that is, they are characteristic of both temperate and high zones. The tropical zone of the Atlantic Ocean is characterized by: fish - various sharks, flying fish, sailboats, various types of tuna and luminous anchovies; from animals - sea turtles, sperm whales, river dolphin inia; cephalopods are also numerous - various types of squids, octopuses, 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 travels and the first sea charts. Their voyages reached the Iberian Peninsula, England and the mouth of the Elbe. In the 4th century BC, Pytheas (Pytheas), while sailing in the North Atlantic, determined the coordinates of a number of points and described the tidal phenomena in the Atlantic Ocean. Mentions of the Canary Islands date back to the 1st century AD. In the 9th-10th centuries, the Normans (Eirik Raudi and his son Leif Eirikson) crossed the ocean, visited Iceland, Greenland, Newfoundland and explored the coast of North America up to 40 ° north latitude. During the Age of Discovery (mid-15th - mid-17th century), navigators (mainly the Portuguese and Spaniards) mastered the route 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 H. 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 for the first time passed from the Atlantic Ocean to the Pacific Ocean through 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. Buffin, 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 (the continent of 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. In 1749, the Englishman G. Ellis carried out the first temperature measurements at various depths, repeated by the Englishman J. Cook (1772), the Swiss O. Saussure (1780), Russian I.F. Kruzenshtern (1803) and others. In the 19th century, the Atlantic Ocean became a testing ground for testing new methods for studying depths, new techniques and new approaches to organizing work. For the first time, bathometers, deep-sea thermometers, thermal depth gauges, deep-sea trawls and dredges are used. Of the most significant, 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 leadership of J. Ross (1840-43); American - on the "Seyklab" and "Arktika" under the leadership of M.F. Mori (1856-57). Real complex oceanographic research of the ocean began with an expedition on the English corvette "Challenger", led by C.W. Thomson (1872-76). The following significant expeditions were carried out on the ships 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 led 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. Since 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 is still active today, organizing and coordinating ocean research.

After the 2nd World War, the echo sounder began to be widely used to study the ocean floor. This made it possible to obtain a real picture of the topography of the ocean floor. In the 1950-70s, complex geophysical and geological studies of the Atlantic Ocean were carried out and the features of the topography of its bottom and tectonics, and the structure of the sedimentary strata were established. Many large forms of bottom topography (submarine ridges, mountains, trenches, fault zones, vast basins and uplifts) have been identified, and geomorphological and tectonic maps have been compiled.

The third stage of ocean research is mainly aimed at studying its role in the global processes of matter and energy transfer and its influence on climate formation. The complexity and wide range of research work required extensive international cooperation. The Scientific Committee for Oceanographic Research (SCOR), formed in 1957, the Intergovernmental Oceanographic Commission of UNESCO (IOC), which has been operating since 1960, and other international organizations play an important role in coordinating and organizing international research. In 1957-58, a lot of work was carried out within the framework of the first International Geophysical Year (IGY). Subsequently, large international projects were aimed not only at studying individual parts of the Atlantic Ocean (for example, EQUALANT I-III; 1962-1964; Polygon, 1970; SICAR, 1970-75; POLIMODE, 1977; TOGA, 1985-89), but also at its study as part of the World Ocean (GEOSECS, 1973-74; WOCE, 1990-96, etc.). 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 Soviet deep-sea submersibles Mir explored the unique ecosystems of the geothermal regions of the ocean's rift zone. If in the early 1980s there were about 20 international ocean research projects, then by the 21st century - over 100. The largest programs are: "International Geosphere-Biosphere Program" (since 1986, 77 countries participate), it includes projects "Interaction land - ocean in the coastal zone" (LOICZ), "Global flows of matter in the ocean" (JGOFS), "Dynamics of global ocean 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, as well as other seas and oceans, goes in several main areas: transport and communications, fishing, mining, energy, recreation.

Transport. For 5 centuries, the Atlantic Ocean has played a leading role in shipping. 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 turnover; at the end of the 20th century, up to 3.5 billion tons of cargo per year were transported through its waters (according to IOC). About 1/2 of the volume of traffic is oil, gas and oil products, 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). The sea routes of the Norwegian, Northern and inland seas of Europe (Baltic, Mediterranean and Black) adjoin this direction. Mainly raw materials (coal, ores, cotton, timber, etc.) and general cargo are transported. Other important directions of transportation are the South Atlantic: Europe - Central (Panama, etc.) and South America (Rio de Janeiro, Buenos Aires); East Atlantic: Europe - South Africa (Cape Town); West Atlantic: North America, South America - southern Africa. Prior to the reconstruction of the Suez Canal (1981), most of the oil tankers from the Indian Basin were forced to go around Africa.

Passenger transportation takes important place in the Atlantic Ocean since the 19th century, when mass emigration from the Old World to America began. The first steam-sailing ship, the 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 the fastest. This prize was awarded, for example, to such famous liners as Lusitania (4 days and 11 hours), Normandie (4 days and 3 hours), Queen Mary (4 days without 3 minutes). The last time the Blue Ribbon was awarded to the US 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 is 5-6 days. The maximum passenger traffic across the Atlantic Ocean occurred in 1956-57, when more than 1 million people were transported per year, in 1958 the volume of passenger traffic by air caught up with sea traffic, and then an increasing part of passengers prefer air transport (the record time for a flight of a supersonic liner "Concord" on the route New York - London - 2 hours 54 minutes). The first non-stop flight across the Atlantic Ocean was made on June 14-15, 1919 by English pilots J. Alcock and A. W. Brown (Newfoundland - Ireland), the first non-stop flight across the Atlantic Ocean alone (from continent to continent) on May 20-21, 1927 - American pilot C. Lindbergh (New York - Paris). At the beginning of the 21st century, almost the entire flow of passengers across the Atlantic Ocean is served by aviation.

Connection. In 1858, when there was no radio communication between the 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 operated 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 man. 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, saithe, saffron cod, etc.), flounder, halibut, sea bass. Production of shellfish (oysters, mussels, squids, 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, the 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 harvested for many centuries. Sardine, horse mackerel, mackerel, tuna, etc. are caught in the central part of the Atlantic Ocean. -Falkland shelf, fishing for both warm-water species (tuna, marlin, swordfish, sardines, etc.) and cold-water species (blue whiting, hake, notothenia, toothfish, etc.). Off the coast of western and southwestern Africa, catching sardines, anchovies and hake. In the Antarctic region of the ocean, planktonic crustaceans (krill), marine mammals, among fish - notothenia, toothfish, silverfish, etc., are of commercial importance. decades, it has declined sharply due to the depletion of biological resources and due to environmental measures, including intergovernmental agreements to limit their extraction.

Mineral resources. The mineral wealth of the ocean floor is being developed more and more actively. Oil and combustible gas fields 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). Major offshore production centers: Gulf of Venezuela, Maracaibo lagoon (Maracaiba oil and gas basin), Gulf of Mexico (Gulf of Mexico oil and gas basin), Gulf of Paria (Orinok 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 (North Sea oil and gas region), etc. Placer deposits of heavy minerals are common along many coasts. The largest development of alluvial deposits of ilmenite, monocyte, zircon, rutile are carried out off the coast of Florida. Similar 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. On the shelf of southwestern Africa, the development of coastal marine diamond placers is underway. Gold-bearing placers were found off the coast of Nova Scotia at depths of 25-45 m. In the Atlantic Ocean, one of the world's largest iron ore deposits, Wabana, has been explored (in Conception Bay off the coast of Newfoundland), iron ore is also being 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 the coastal zone of the ocean, sand is mined for construction and glass production, 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 still unprofitable. The total mass of phosphorites on the continental shelf is estimated at 300 billion tons. Large fields of ferromanganese nodules have been found at the bottom of the North American Basin and on the Blake Plateau; their total reserves in the Atlantic Ocean are estimated at 45 billion tons.

Recreational resources. From the 2nd half of the 20th century great importance for the economies of coastal countries has a use recreational resources ocean. Old resorts are being developed and new ones are being built. Since the 1970s, ocean liners have been laid down, intended only for cruises, 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 cruise liners Atlantic Ocean - Mediterranean and caribbean and the Gulf of Mexico. Since the end of the 20th - the beginning of the 21st century, 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 Canaries, Azores, Bermuda, the Caribbean Sea and the Gulf of Mexico.

Energy. The energy of the sea tides of the Atlantic Ocean is estimated at about 250 million kW. 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 the hydrothermal energy of the ocean (temperature difference in surface and deep waters) is also considered promising; a hydrothermal station operates on the coast of Côte 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 St. 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, Abijan, Cape Town. Russian port cities do not have direct access to the Atlantic Ocean and are located on the shores of 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 of the Atlantic Ocean / Ed. editor D. E. Gershanovich. M., 1986; Broeker W.S. The great ocean conveyor // Oceanograpy. 1991 Vol. 4. No. 2; Pushcharovsky Yu. M. Tectonics of the Atlantic with elements of nonlinear geodynamics. M., 1994; World ocean atlas 2001: In 6 vol. Silver Spring, 2002.

P. N. Makkaveev; A. F. Limonov (geological structure).

The ocean arose as a result of the split of the Pangea supercontinent into two large parts, which subsequently formed the modern continents.

The Atlantic Ocean has been known to man since ancient times. Mentioning the ocean, which is called the Atlantic, can be found in the records of the 3rd century. BC. The name arose, probably, from the legendary missing mainland Atlantis. True, it is not clear what territory it designated, because in ancient times people were limited in their means of transportation by sea.

Relief and islands

A distinctive feature of the Atlantic Ocean is a very small number of islands, as well as a complex bottom topography, which forms many pits and gutters. The deepest among them are the Puerto Rico Trench and the South Sandwich Trench, which are over 8 km deep.

Earthquakes and volcanoes have a great influence on the structure of the bottom, the greatest activity of tectonic processes is observed in the equatorial zone. Volcanic activity in the ocean has been going on for 90 million years. The height of many underwater volcanoes exceeds 5 km. The largest and most famous are found in the Puerto Rico and Yuno Sandwich trenches, as well as on the Mid-Atlantic Ridge.

Climate

The large meridional extent of the ocean from north to south explains the diversity of climatic conditions on the surface of the ocean. In the equatorial zone, slight temperature fluctuations throughout the year and an average temperature of +27 degrees. The exchange of water with the Arctic Ocean also has a huge impact on ocean temperature. From the north, tens of thousands of icebergs drift into the Atlantic Ocean, reaching almost tropical waters.

The Gulf Stream, the largest current on the planet, is born off the southeastern coast of North America. Water consumption per day is 82 million cubic meters. m., which is 60 times the flow of all rivers. The width of the current reaches 75 km. wide, and the depth is 700 m. The speed of the current varies between 6-30 km / h. The Gulf Stream carries warm waters, the temperature of the upper layer of the current is 26 degrees.

In the school course of studying the oceans, the Atlantic must be passed. This water area is quite interesting, which is why we will pay attention to it in our article. So, here is the characteristic of the Atlantic Ocean according to the plan:

1. Hydronym.
2. Basic moments.
3. Temperature regime.
4. Salinity of water.
5. Seas and islands of the Atlantic Ocean.
6. Flora and fauna.
7. Minerals.
8. Problems.

You will also find here a brief comparative description of the Pacific and Atlantic oceans.

hydronym

The Atlantic Ocean, whose characteristics are presented below, got its name thanks to the ancient Greeks, who believed that the hero of myths, Atlas, holds the sky at the edge of the Earth. The modern name was established in the 16th century, during the time of great navigators and discoveries.

Basic moments

The Atlantic Ocean stretches along the globe from north to south from Antarctica to Antarctica, washing 5 continents: Antarctica, North and South America, Eurasia and Africa. Its area is 91.6 million square kilometers. The deepest point of the Atlantic is the Puerto Rican Trench (8742 m), and the average depth is about 3.7 thousand m.

A characteristic feature of the second largest ocean is its elongated shape. The Mid-Atlantic Ridge runs along the Atlantic, which separates South American, Caribbean and North American in the west; in the east - African and Eurasian. The length of the ridge is 16 thousand km, and the width is about 1 km. Lava eruptions and earthquakes often occur here. The discovery of the Mid-Atlantic Ridge is associated with the laying of a telegraph cable that connected America and Northern Europe in the middle of the 19th century.

Temperature regime

The North Trade Wind, Gulf Stream, North Atlantic, Labrador, Canary and others are currents that shape not only the climate, but the entire Atlantic Ocean. Characteristic temperature regime shows the following dynamics: the average water temperature is about 16.9 °C. Conventionally, the ocean can be divided along the equator into 2 parts: northern and southern, each of which has its own climatic features, thanks to the Gulf Stream. The width of the water area near the equator is the smallest, so the influence of the continents is most noticeable here.

Despite the fact that the Atlantic Ocean is considered warm, its extreme southern and northern sections can reach temperatures of 0 ° C and below. Therefore, drifting icebergs can often be found here. Today, their movement is tracked by artificial Earth satellites.

Atlantic Ocean: water feature

The Atlantic Ocean is the most salty. The average salt content is 34.5 ppm. Salinity largely depends on precipitation, fresh water inflow from rivers. The saltiest is in tropical latitudes, because there is almost no precipitation here, strong evaporation of moisture due to high temperature and almost no fresh water.

Seas and islands of the Atlantic Ocean

Most of the islands are located near the mainland, which determines their continental origin: Great Britain, Ireland and others. There are also volcanic ones here: Canaries, Iceland. But Bermuda is of coral origin.

The indentation of the coastline, bays, seas fully describe the Atlantic Ocean. The characteristics of these reservoirs are very interesting. First of all, let's start with the seas. They are divided into 2 types: internal - Azov, Black, Mediterranean, Baltic, and external - Caribbean and Northern, etc. Also here you can observe bays that are not inferior in size to the seas, for example, Mexican or Biscay. In the Atlantic Ocean there is an unusual sea that has no shores - Sargasso. It got its name because of which its bottom is covered. These algae are covered with air bubbles, which is why they are also called

Flora and fauna

The organic world of the Atlantic is characterized by a variety of living organisms. Here grow red, brown, green algae, a large number of species of phytoplankton (more than 200). Thousands of species of animals live in cold zones, and tens of thousands in warm tropical zones. Whales, seals, fur seals, a lot of fish swim in the Atlantic Ocean: cod, herring, flounder, sardine, etc. Penguins and frigatebirds live in the northern latitudes. Large aquatic animals manatees live off the coast of Africa. They eat plants, which is why they are also called
It so happened historically that the Atlantic Ocean has become a source of fish for the food industry (2/5 of the world catch). Whales, walruses, seals and other animals are also hunted here. It satisfies our needs for lobster, oysters, lobsters, crabs.

Minerals

The ocean floor is very rich in various things and Canada mines coal here. The Gulf of Mexico and Guinea have large reserves of oil and natural gas.

Problems

The increase in anthropogenic influence on the Atlantic Ocean has a negative impact on its inhabitants, and it is no longer able to restore its biological resources on its own. A dangerous situation is observed in the Black and Mediterranean Seas, and the Baltic Sea is considered one of the dirtiest in the world.

Comparative characteristics of the Atlantic Ocean and the Pacific (briefly)

In order to make a brief description of the two oceans, you need to use a clear plan:

• The size of the water areas. Atlantic covers an area of ​​more than 91 million square meters. km, Quiet - 178.684 million square meters. km. Based on this, certain conclusions can be drawn. The Pacific Ocean is the largest, the Atlantic - in second place in terms of area.
• Depth. If we compare the depth indicator, then in the Pacific Ocean the average level stops at around 3976 m, in the Atlantic - 3736 m. maximum depth, then in the first case - 11022 m, in the second - 8742 m.
• Water volume. According to this criterion, the Atlantic Ocean also remains in second place. His figure is 329.66 million cubic meters. km, when in the Pacific - 710.36 million cubic meters. m.
• Location. Atlantic Ocean coordinates - 0° N. sh. 30°W D., washes the following continents and islands: Greenland, Iceland (north), Eurasia, Africa (east), America (west), Antarctica (South). Pacific Ocean coordinates - 009 ° s. sh. 157°W e, located between Antarctica (south), North and South America (east), Australia and Eurasia (west).

Summing up

This article presents a brief description of the Atlantic Ocean, after reading which, you can already have a sufficient idea of ​​\u200b\u200bthis area.