Where is the Baltic? Baltic Sea: vacation

BALTIC SEA(Late Latin Mare Balticum, among the ancient Slavs - the Varangian Sea or Sveiskoe), the inland sea of ​​the Atlantic Ocean, between the Scandinavian Peninsula and the mainland shores of Northwestern Europe. It washes the shores of Sweden, Finland, Russia, Estonia, Latvia, Lithuania, Poland, Germany, Denmark. In the southwest it connects with the North Sea Danish Straits. The sea border of the Baltic Sea runs along the southern entrances of the Öresund, Great Belt, and Little Belt straits. Area 419 thousand km 2, volume 21.5 thousand km 3. The greatest depth is 470 m. Depths above the rapids of the Danish Straits: Darser - 18 m, Drogden - 7 m. The cross section above the rapids is 0.225 and 0.08 km 2, respectively, which limits water exchange with the North Sea. The Baltic Sea extends deep into the Eurasian continent. The heavily indented coastline forms numerous bays and bays. The largest bays: Gulf of Bothnia, Gulf of Finland, Gulf of Riga, Curonian Lagoon, Szczecin Bay, Gulf of Gdansk. The shores of the Baltic Sea in the north are high, rocky, predominantly of the skerry and fjord types; in the south and southeast they are mostly low-lying, lagoon-type, with sandy and pebble beaches. The largest islands are Gotland, Bornholm, Saaremaa, Muhu, Hiiumaa, Öland and Rügen. There are many small rocky islands - skerries, located along the northern shores (there are over 6 thousand in the Åland group of islands).

Relief and geological structure of the bottom

The Baltic Sea is shallow, lies entirely within the shelf, depths up to 200 m occupy 99.8% of its area. The shallowest waters are the Gulf of Finland, the Gulf of Bothnia and the Gulf of Riga. Their bottom areas have a leveled accumulative topography and a well-developed cover of loose sediments. Most of the bottom of the sea is characterized by highly dissected relief. The bottom of its basin has depressions delimited by hills and the bases of islands: in the west - Bornholm (105 m) and Arkon (53 m), in the center - Gotland (249 m) and Gdansk (116 m); to the north of the island of Gotland, the deepest depression, the Landsort depression (up to 470 m), stretches from northeast to southwest. Numerous stone ridges, in the central part of the sea there are ledges - continuations of cliffs stretching from the northern coast of Estonia to the northern tip of the island of Öland, underwater valleys, glacial-accumulative landforms flooded by the sea.

B. m. occupies a depression in the ancient west East European Platform. The northern part of the sea is located on the southern slope Baltic Shield; the central and southern parts belong to a large negative structure of the ancient platform - the Baltic syneclise. The extreme southwestern part of the sea is included in the young Western European Platform. The bottom in the north of the Baltic Sea is composed primarily of complexes of Precambrian age, overlain by an intermittent cover of glacial and modern marine sediments. In the central part of the sea, Silurian and Devonian sediments take part in the structure of the bottom. The ledges traced here are formed by Cambrian-Ordovician and Silurian rocks. Paleozoic complexes in the south are overlain by thick layers of glacial and marine sediments.

During the last glacial epoch (late Pleistocene), the Baltic Sea basin was completely blocked by an ice sheet, after the melting of which the Baltic Glacial Lake was formed. At the end of the Late Pleistocene, ca. 13 thousand years ago, the lake connected with the ocean and the depression was filled with sea waters. The connection with the ocean was interrupted between 9 and 7.5 thousand years ago, after which a marine transgression followed, the deposits of which are known on the modern coast of the Baltic Sea. In the northern part of the Baltic Sea, uplift continues, the speed of which reaches 1 cm per year.

Bottom sediments at depths of over 80 m are represented by clayey silts, under which lies banded clay on glacial deposits; at shallower depths, silt is mixed with sand; sand is common in coastal areas. There are boulders of glacial origin.

Climate

The Mediterranean region is characterized by a temperate maritime climate with continental features. Its seasonal features are determined by the interaction of pressure centers: the Icelandic minimum and the Azores maximum in the west and the Siberian maximum in the east. Cyclonic activity reaches its greatest intensity in the autumn-winter months, when cyclones bring cloudy, rainy weather with strong westerly and south-westerly winds. The average air temperature in February ranges from –1.1 °C in the south, –3 °C in the central part of the sea to –8 °C in the north and east and to –10 °C in the northern part of the Gulf of Bothnia. Rarely and for a short time, cold Arctic air penetrating the Baltic lowers the temperature to –35 °C. In summer, westerly winds also blow, but with little strength, bringing cool, humid weather from the Atlantic. The air temperature in July is 14–15 °C in the Gulf of Bothnia and 16–18 °C in other areas of the sea. Rare arrivals of warm Mediterranean air cause short-term increases in temperature to 22–24 °C. The annual precipitation ranges from 400 mm in the north to 800 mm in the south. The greatest number of days with fog (up to 59 days per year) is observed in the south and central part of the Gulf of Bottom, the smallest (22 days per year) - in the north of the Gulf of Bothnia.

Hydrological regime

The hydrological conditions of the Baltic Sea are determined by its climate, significant influx of fresh water, and limited water exchange with the North Sea. Approx. flows into the B. m. 250 rec. The average river flow is 472 km 3 per year. The largest rivers are: Neva - 83.5 km 3, Vistula - 30, Neman - 21, Western Dvina - 20 km 3 per year. Freshwater flow is distributed unevenly across the territory. The Gulf of Bothnia receives 181, the Gulf of Finland - 110, the Gulf of Riga - 37, and the central part of the Baltic Sea - 112 km 3 per year. The amount of fresh water from atmospheric precipitation (172 km 3 per year) is equal to evaporation. Water exchange with the North Sea averages 1,660 km 3 per year. Fresher waters with a surface runoff flow leave the Baltic Sea into the North Sea, while salty North Sea water with a bottom current flows through the straits from the North Sea. Strong westerly winds usually increase the inflow, and eastern winds - the outflow of water from the Baltic Sea through the Danish Straits.

The hydrological structure of the Baltic Sea in most regions is represented by surface and deep water masses separated by a thin intermediate layer. The surface water mass occupies a layer from 20 to (in some places) 90 m, its temperature throughout the year ranges from 0 to 20 °C, and salinity is usually in the range of 7–8‰. This water mass is formed in the sea itself as a result of the interaction of sea waters with fresh waters from atmospheric precipitation and river runoff. It has winter and summer modifications, differing mainly in temperature. In the warm season, the presence of a cold intermediate layer is noted, which is associated with the summer heating of water on the surface. The deep water mass occupies a layer from 50–100 m to the bottom, its temperature varies from 1 to 15 °C, salinity - from 10.0 to 18.5‰. Deep water is formed in the bottom layer as a result of mixing with high salinity water coming from the North Sea. Renewal and ventilation of bottom waters are highly dependent on the influx of North Sea water, which is subject to interannual variability. With a reduction in the influx of salt water into the sea at great depths and in depressions in the bottom topography, conditions are created for the occurrence of dead water phenomena. Seasonal changes in water temperature affect the layer from the surface to 50–60 m and usually do not penetrate deeper.

Wind waves develop especially strongly in autumn-winter with long and strong south-west winds, when waves 5–6 m high and 50–70 m long are observed. The highest waves are observed in November. In winter, sea ice prevents the development of waves.

In the Baltic Sea, cyclonic (counterclockwise) circulation of water, complicated by vortex formations of different scales, can be traced everywhere. The speed of constant currents is usually approx. 3–4 cm/s, but in some areas at times they increase to 10–15 cm/s. Due to low speeds, currents are unstable, their pattern is often disrupted by winds. Storm winds cause strong wind currents with speeds of up to 150 cm/s, which quickly fade after the storm.

The tides in the Baltic Sea, due to their insignificant connection with the ocean, are weakly expressed; the height is 0.1–0.2 m. Surge fluctuations in the level reach significant values ​​(at the tops of the bays up to 2 m). The combined action of wind and sudden changes in atmospheric pressure causes seiche level fluctuations with a period of 24–26 hours. The magnitude of such fluctuations ranges from 0.3 m in the open sea to 1.5 m in the Gulf of Finland. Seiche waves with surge westerly winds sometimes cause the level at the top of the Gulf of Finland to rise to 3–4 m, which delays the flow of the Neva and leads to floods in St. Petersburg, sometimes of a catastrophic nature: in November 1824 about 410 cm, in September 1924 - 369 cm .

The water temperature on the surface of the sea varies greatly from season to season. In August in the Gulf of Finland the water warms up to 15–17 °C, in the Gulf of Bothnia - 9–13 °C, in the central part of the sea– 14–18 °C, in the southern regions reaches 20 °C. In February, in the open part of the sea, the surface water temperature is 1–3 °C, in bays and bays it is below 0 °C. The salinity of water on the surface is 11‰ at the exit from the Danish Straits, 6–8‰ in the central part of the sea, 2‰ and less at the tops of the Gulf of Bothnia and the Gulf of Finland.

B. m. refers to the so-called. brackish basins, in which the temperature of greatest density is above the freezing point, which leads to an intensification of the process of sea ice formation. Ice formation begins in November in bays and off the coast, and later in the open sea. In severe winters, ice cover covers the entire northern part of the sea and the coastal waters of its central and southern parts. The thickness of fast ice (immobile) reaches 1 m, drifting ice - from 0.4 to 0.6 m. Ice melting begins at the end of March, spreads from southwest to northeast and ends in June.

History of the study

The first information about B.'s research is associated with the Normans. All R. 7th century they penetrated the Gulf of Bothnia, discovered the Åland Islands, and in the 2nd half. 7th–8th centuries reached the western coast of the Baltic states, discovered the Moonsund archipelago, and first penetrated the Gulf of Riga in the 9th–10th centuries. used the coast from the mouth of the Neva to the Bay of Gdansk for trading and pirate activities. Hydrographic and cartographic work was carried out by the Russians in the Gulf of Finland at the beginning of the 18th century. In 1738, F. I. Soimonov published an atlas of biomass, compiled from domestic and foreign sources. All R. 18th century long-term research was carried out by A. I. Nagaev, who compiled a detailed navigation chart for the sea. The first deep-sea hydrological studies in the middle. 1880s were carried out by S. O. Makarov. Since 1920, hydrological work has been carried out by the Hydrographic Directorate of the Navy, the State Hydrological Institute (Leningrad), and from the 2nd half. 20th century extensive comprehensive research was launched under the leadership of the Leningrad (St. Petersburg) branch of the State Oceanographic Institute of the Russian Academy of Sciences.

Economic use

Fish resources consist of freshwater species living in the desalinated waters of the bays (crucian carp, bream, pike, pike perch, chub), the Baltic salmon stock and purely marine species distributed mainly in the central part of the sea (cod, herring, smelt, vendace, sprat). In the Baltic Sea, fishing is carried out for herring, sprat, herring, smelt, flounder, cod, perch, and others. A unique fishing object is eel. Placers of amber are common on the coast of the Baltic Sea; mining is carried out near Kaliningrad (Russia). Oil reserves were discovered at the bottom of the sea, and industrial development began. Iron ore is mined off the coast of Finland. The importance of the B. m. as a transport artery is great. Large-scale transportation of liquid, bulk, and general cargo is carried out along the B. m. A significant part of the foreign trade of Denmark, Germany, Poland, Russia, Lithuania, Latvia, Estonia, Finland, and Sweden is carried out through the international market. The cargo turnover is dominated by oil products (from Russian ports and from the Atlantic Ocean), coal (from Poland, Russia), timber (from Finland, Sweden, Russia), pulp and paper (from Sweden and Finland), iron ore (from Sweden); Machinery and equipment also play an important role, the major producers and consumers of which are countries located on the shores and in the basin of the Baltic Sea.

A gas pipeline (2 threads, each with a diameter of 1220 mm) “Nord Stream” was laid along the bottom of the Baltic Sea between Russia and Germany. Passes from Portovaya Bay near Vyborg (Leningrad Region) to Lubmin near Greifswald (Germany, federal state of Mecklenburg-Vorpommern); length 1224 km (the longest underwater gas pipeline in the world). The throughput capacity (capacity) of the gas pipeline is 55 billion m³ of gas per year. The maximum sea depth where the pipe passes is 210 m. 148 sea vessels were involved in the construction. The total mass of steel used in the construction of the gas pipeline is 2.42 million tons.

At the preparatory stage, Nord Stream spent approx. 100 million euros. In 1997, preparatory work for the construction of the offshore section began: scientific research was carried out, on the basis of which the approximate route of the gas pipeline was determined. In 2000, by decision of the European Union Commission on Energy and Transport, the project was awarded the status of TEN (“Trans-European Networks”). Construction of the gas pipeline began on April 9, 2010. The first line of the gas pipeline was put into operation on November 8, 2011, the second on October 8, 2012.

In September 2015, a Shareholders Agreement was signed for the implementation of the project, called Nord Stream 2. On July 8, 2016, the Nord Stream 2 company completed a tender to select a contractor to apply a concrete weight coating to the gas pipeline pipes.

344 vessels with a total carrying capacity of 1,196.6 thousand tons of deadweight are registered in the ports of the Baltic Sea. The largest ports: St. Petersburg, Kaliningrad, Vyborg, Baltiysk (all - Russia); Tallinn (Estonia); Riga, Liepaja, Ventspils (all Latvia); Klaipeda (Lithuania); Gdansk, Gdynia, Szczecin (all – Poland); Rostock - Warnemünde, Lubeck, Kiel (all - Germany); Copenhagen (Denmark); Malmo, Stockholm, Luleå (all Sweden); Turku, Helsinki and Kotka (all Finland). Sea passenger and ferry services have been developed: Copenhagen - Malmö, Trelleborg - Sassnitz (railway ferries), Nortelje - Turku (car ferry), etc. Crossings across the straits: Great Belt (1998; length 6790 m), Little Belt (both - Denmark; 1970; 1700 m), Oresund (Denmark - Sweden; 2000; 16 km); it is planned to build a ferry across the Femer Strait (Denmark - Germany; 2018; 19 km). Due to the shallow depths, many places are inaccessible to ships with significant draft, but the largest cruise ships sail through the Danish Straits into the Atlantic Ocean.

There are many resort places on the southern and southeastern coasts: Sestroretsk, Zelenogorsk, Svetlogorsk, Pionersky, Zelenogradsk, Curonian Spit (all in Russia); Pärnu, Narva-Joesuu (both Estonia); Jurmala, Saulkrasti (both Latvia); Palanga, Neringa (both Lithuania); Sopot, Hel, Kolobrzeg, Koszalin (all – Poland); Albeck, Binz, Heiligendamm, Timmendorf (all – Germany); Öland island (Sweden).

Ecological state

The Baltic Sea, which has difficult water exchange with the World Ocean (water renewal lasts about 30 years), is surrounded by industrialized countries and is experiencing extremely intense anthropogenic pressure. The main environmental problems are associated with the burial of chemical weapons at the bottom of the sea, the discharge of wastewater from large cities into the sea, the wash-off of chemical fertilizers used in agriculture, and especially with shipping - one of the most intensive in the world (mainly oil tankers). After the Convention for the Protection of the Marine Environment came into force in 1980, the environmental situation improved due to the commissioning of a large number of wastewater treatment plants, a reduction in the use of chemical fertilizers, and monitoring the technical condition of ships. The concentration of toxic substances such as DDT and polychlorinated biphenyl, petroleum carbons has decreased. The dioxin content in Baltic herring is 3 times lower than the maximum permissible concentration, and the gray seal population has recovered. The issue of giving the Baltic Sea the status of a particularly vulnerable marine area is being considered.

Baltic Sea(also called the Eastern Sea) is considered an inland sea that extends deep into the continent.

The northern extreme point of the Baltic Sea is located near the Arctic Circle, the southern - near the German city of Wismar, the western - near the city of Flensburg, and the eastern - near St. Petersburg. This sea belongs to the ocean.

General information about the Baltic

The area of ​​the sea (not including islands) is 415 km. sq. It washes the shores of the following states:

  • Estonia;
  • Russia;
  • Lithuania;
  • Germany;
  • Latvia;
  • Poland
  • Latvia;
  • Denmark;
  • Finland;
  • * Sweden.

Large bays are considered: Bothnian, Finnish, Riga, Kursk (separated by an oblique). The largest islands: Öland, Wolin, Alandia, Gotland, Als, Saaremaa, Muhu, Men, Usedom, Fore and others. The largest rivers: Zapadnya Dvina, Neva, Vistula, Venta, Narva, Pregolya.

The Baltic Sea, through the Volga-Baltic basin, opens onto and is located on the continental shelf. In the area of ​​islands, shallows and banks, the depth varies within 12 meters. There are a couple of basins where the depth reaches 200 meters. The Landsort Basin is considered the deepest (470 meters), the depth of the basin reaches 250 meters, and in the Gulf of Bothnia - 254 meters.

In the southern region the seabed is flat, and in the north it is predominantly rocky. A huge part of the bottom is covered with sediments of glacial origin of various colors (green, brown, black).

A special feature of the Baltic Sea is that there is an excess of fresh water, which is formed due to river runoff and precipitation.

Its surface brackish waters constantly flow into. During storms, the exchange between these seas changes, as water is mixed from the bottom in the straits. The salinity of the sea is decreasing from the Danish Straits (20 ppm) to the east (in the Gulf of Bothnia it is 3 ppm, and in the Gulf of Finland – 2 ppm). Tides can be diurnal or semidiurnal (do not exceed 20 cm).

When compared with other seas, the disturbances in the Baltic Sea are completely insignificant. In the central parts of the sea, waves can reach 3-3.5 meters, less often - 4 meters. During large storms, waves 10-11 meters high were recorded. The clearest water with a bluish-green tint is observed in the Gulf of Bothnia; in coastal areas it is more turbid and has a yellowish-green color. Due to the development of plankton, the lowest water transparency is observed in summer. The soils of the coastal zone are varied: in the southern regions there is sand, in the east there is silt and sand, and on the northern coast there is stone.

Climate of the Baltic Sea

The sea temperature is generally lower than in other seas. In the mornings in the summer, thanks to the southern winds that drive the upper warm layers into the ocean, the temperature sometimes drops below 12 degrees. When northerly winds begin to blow, surface waters become significantly warmer. The highest temperature is in August - about 18 C. In January it varies from 0 to 3 C.

Due to its low salinity, harsh winters and shallow depth, the Baltic Sea often freezes, although not every winter.

Flora and fauna

The water in the Baltic Sea changes from sea salt to fresh water. Marine mollusks live only in the western region of the sea, where the water is saltier. Fish here include sprat, cod, and herring. The Gulf of Finland is home to smelt, vendace, salmon and others. Seals live in the area of ​​the Åland Islands.

Due to the presence of many islands, rocks, and reefs in the sea, sailing in the Baltic Sea is quite dangerous. This danger is somewhat reduced due to the presence of a large number of lighthouses here (most of them). The largest cruise ships leave the Danish Straits and enter the Atlantic Ocean. The Great Belt Bridge is considered the most difficult place. The largest ports: Tallinn, Baltiysk, Lubeck, Riga, Stockholm, Szczecin, Rostock, Kiel, Vyborg, Gdansk, St. Petersburg;

  • Ptolemy called this sea the Venedian, which comes from the name of the Slavic peoples who lived in ancient times in the southern part of the coast - the Wends or Wends;
  • The famous route from the Varangians to the Greeks ran through the Baltic Sea;
  • "The Tale of Bygone Years" calls it Varangian Sea;
  • The name "Baltic Sea" appears for the first time in the treatise of Adam of Bremen in 1080;
  • This sea is rich in oil, manganese, iron and amber. The Nord Stream gas pipeline runs along its bottom;
  • Every year on March 22, Baltic Sea Environmental Protection Day is celebrated. This decision was made by the Helsinki Commission in 1986.

Resorts

Among the resorts of the Baltic Sea, the most famous are: Zelenogorsk, Svetlogorsk, Zelenogradsk, Pionersky (Russia), Saulkrasti and

HGIOL

The northernmost point of the Baltic Sea is located near the Arctic Circle (65°40" N), the southernmost point is near the city of Wismar (53°45" N).

The westernmost point is located in the Flensburg area (9°10" E), the easternmost point is in the St. Petersburg area (30°15" E)

Sea surface area (without islands) is 419 thousand km². The volume of water is 21.5 thousand km³. Due to the huge flow of rivers, the water has low salinity and therefore the sea is brackish. It is the largest sea in the world with such a feature.

Geological history

The weight of the ice caused a significant deflection of the earth's crust, part of which was below ocean level. With the end of the last ice age, these territories are freed from ice, and the depression formed by the depression of the crust is filled with water:

Physiographical sketch

The Baltic Sea extends deep into the land of Europe, washing the shores of Russia, Estonia, Latvia, Lithuania, Poland, Germany, Denmark, Sweden and Finland.

Large bays of the Baltic Sea: Finnish, Bothnian, Riga, Curonian (a freshwater bay separated from the sea by the sandy Curonian Spit).

The major rivers flowing into the Baltic Sea are the Neva, Narva, Western Dvina (Daugava), Neman, Pregolya, Vistula, Oder and Venta.

Bottom relief

The Baltic Sea lies within the continental shelf. The average sea depth is 51 meters. In areas of shallows, banks, and near islands, shallow depths are observed (up to 12 meters). There are several basins in which depths reach 200 meters. The deepest basin is the Landsort basin ( 58°38′ N. w. 18°04′ E. d. HGIOL) with a maximum sea depth of 470 meters. In the Gulf of Bothnia the maximum depth is 293 meters, in the Gotland Basin - 249 meters.

The bottom in the southern part of the sea is flat, in the north it is uneven and rocky. In coastal areas, sands are common among bottom sediments, but most of the seabed is covered with sediments of green, black or brown clayey silt of glacial origin.

Hydrological regime

A special feature of the hydrological regime of the Baltic Sea is a large excess of fresh water, formed due to precipitation and river flow. The brackish surface waters of the Baltic Sea flow through the Danish Straits into the North Sea, and the salty waters of the North Sea enter the Baltic Sea with the deep current. During storms, when the water in the straits is mixed to the very bottom, the water exchange between the seas changes - along the entire cross-section of the straits, water can flow into both the North and Baltic Seas.

In 2003, 21 incidents of chemical weapons entering fishing nets were recorded in the Baltic Sea - all in the form of blobs of mustard gas weighing approximately 1,005 kg.

In 2011, paraffin was discharged into the sea, which spread throughout the sea. Tourists found large pieces of paraffin on the beach. [ ]

Natural resources

The development of deposits may be hampered by strict environmental requirements associated with insignificant water exchange between the sea and the ocean, and anthropogenic water pollution by runoff from the territory of coastal states, which contribute to increased eutrophication.

The Nord Stream gas pipeline was laid along the bottom of the Baltic Sea.

Sea transport

Recreational resources

Titles

First time title Baltic Sea(lat. mare Balticum) found in Adam of Bremen in his treatise “Acts of the Archbishops of the Hamburg Church” (lat. Gesta Hammaburgensis Ecclesiae Pontificum) .

In the Tale of Bygone Years the Baltic Sea is named Varyazhsky by sea. Historically in Russian the sea was called Varyazhsky, and then Sveisky(Swedish). Under Peter I, the German name became stronger - Ostzeyskoe sea. The modern name has been used since 1884.

see also

Notes

  1. // Military Encyclopedia: [in 18 volumes] / ed. V. F. Novitsky [and others]. - St. Petersburg. ; [M.]: Type. t-va I. D. Sytin, 1911-1915.
  2. Baltic Sea // Great Russian Encyclopedia: [in 35 volumes] / ch. ed. Yu. S. Osipov. - M.: Great Russian Encyclopedia, 2004-2017.
  3. Albert K. Jensen - The Living World of the Oceans. St. Petersburg: Gidrometeoizdat, 1994. - 256 p. ISBN 5-286-00160-2

The Baltic Sea, deeply cut into the land, has very complex coastlines and forms large bays: Bothnian, Finnish and Riga. This sea has land borders almost everywhere, and only from the Danish Straits (Great and Little Belt, Sound, Farman Belt) is it separated by conditional lines running between certain points on their coasts. Due to their peculiar regime, the Danish Straits do not belong to the Baltic Sea. They connect it with the North Sea and through it with the Atlantic Ocean. The depths above the rapids separating the Baltic Sea from the straits are small: above the Darser rapids - 18 m, above the Drogden rapids - 7 m. The cross-sectional area in these places is 0.225 and 0.08 km 2, respectively. The Baltic Sea is weakly connected to the North Sea and has limited water exchange with it, and even more so with the Atlantic Ocean.

It belongs to the type of inland seas. Its area is 419 thousand km 2, volume - 21.5 thousand km 3, average depth - 51 m, greatest depth - 470 m.

Bottom relief

The bottom topography of the Baltic Sea is uneven. The sea lies entirely within the shelf. The bottom of its basin is indented by underwater depressions, separated by hills and the bases of islands. In the western part of the sea there are shallow Arkona (53 m) and Bornholm (105 m) depressions, separated by the island. Bornholm. In the central regions of the sea, quite vast spaces are occupied by the Gotland (up to 250 m) and Gdansk (up to 116 m) basins. North of the island. Gotland lies the Landsort Depression, where the greatest depth of the Baltic Sea is recorded. This depression forms a narrow trench with depths of over 400 m, which stretches from northeast to southwest and then south. Between this trench and the Norrköping depression located to the south, there is an underwater rise with depths of about 112 m. Further south, the depths increase slightly again. On the border of the central regions with the Gulf of Finland the depth is about 100 m, with the Gulf of Bothnia - approximately 50 m and with the Riga - 25-30 m. The bottom topography of these bays is very complex.

Bottom topography and currents of the Baltic Sea

Climate

The climate of the Baltic Sea is maritime at temperate latitudes with continental features. The peculiar configuration of the sea and its significant extent from north to south and from west to east create differences in climatic conditions in different areas of the sea.

The Icelandic low, as well as the Siberian and Azores anticyclones, have the most significant influence on the weather. The nature of their interaction determines the seasonal characteristics of the weather. In autumn and especially winter, the Icelandic minimum and the Siberian maximum interact intensively, which intensifies cyclonic activity over the sea. In this regard, in autumn and winter, deep cyclones often pass through, bringing with them cloudy weather with strong southwestern and western winds.

In the coldest months - January and February - the average air temperature in the central part of the sea is -3° in the north and –5-8° in the east. With rare and short-term intrusions of cold Arctic air associated with the intensification of the Polar High, the air temperature over the sea drops to -30° and even to -35°.

In the spring-summer season, the Siberian High is destroyed, and the Baltic Sea is affected by the Icelandic Low, the Azores and partly the Polar High. The sea itself is located in a low-pressure zone through which cyclones from the Atlantic Ocean, which are less deep than in winter, pass. Due to this, in spring the winds are very unstable in direction and low in speed. Northerly winds usually cause a cold spring in the Baltic Sea.

In summer, the winds blow predominantly from the west, north-west and south-west, weak to moderate. They are associated with the cool and humid summer weather characteristic of the sea. The average monthly temperature of the warmest month - July - is 14-15° in the Gulf of Bothnia and 16-18° in other areas of the sea. Hot weather is rare. It is caused by short-term inflows of heated Mediterranean air.

Hydrology

About 250 rivers flow into the Baltic Sea. The Neva brings the largest amount of water per year - on average 83.5 km 3 , Vistula - 30 km 3 , Neman - 21 km 3 , Daugava - about 20 km 3 . Runoff is distributed unevenly across regions. Thus, in the Gulf of Bothnia it is 181 km 3 /year, in the Gulf of Finland - 110, in the Gulf of Riga - 37, in the central part of the Baltic - 112 km 3 /year.

Geographical location, shallow water, complex bottom topography, limited water exchange with the North Sea, significant river flow, and climatic features have a decisive influence on hydrological conditions.

The Baltic Sea is characterized by some features of the eastern subtype of the subarctic structure. However, in the shallow Baltic Sea it is represented mainly by surface and partially intermediate waters, significantly transformed under the influence of local conditions (limited water exchange, river flow, etc.). The water masses that make up the structure of the waters of the Baltic Sea are not identical in their characteristics in different areas and change with the seasons. This is one of the distinctive features of the Baltic Sea.

Water temperature and salinity

In most areas of the Baltic Sea, surface and deep water masses are distinguished, between which lies a transition layer.

Surface water (0-20 m, in places 0-90 m) with a temperature from 0 to 20°, a salinity of approximately 7-8‰ is formed in the sea itself as a result of its interaction with the atmosphere (precipitation, evaporation) and with the waters of continental runoff. This water has winter and summer modifications. In the warm season, a cold intermediate layer develops in it, the formation of which is associated with significant summer heating of the sea surface.

Temperature of deep water (50-60 m - bottom, 100 m - bottom) - from 1 to 15°, salinity - 10-18.5‰. Its formation is associated with the entry of deep waters into the sea through the Danish Straits and with mixing processes.

The transition layer (20-60 m, 90-100 m) has a temperature of 2-6°, salinity - 8-10‰, and is formed mainly by mixing surface and deep waters.

In some areas of the sea, the structure of the waters has its own characteristics. For example, in the Arkona region in summer there is no cold intermediate layer, which is explained by the relatively shallow depth of this part of the sea and the influence of horizontal advection. The Bornholm region is characterized by a warm layer (7-11°), observed in winter and summer. It is formed by warm waters coming here from the somewhat warmer Arkona basin.

In winter, the water temperature is slightly lower near the coast than in the open parts of the sea, while off the western coast it is slightly higher than on the eastern coast. Thus, the average monthly water temperature in February near Ventspils is 0.7°, at the same latitude in the open sea - about 2°, and off the western coast - 1°.

Water temperature and salinity on the surface of the Baltic Sea in summer

In summer, the temperature of surface waters varies in different areas of the sea.

The decrease in temperature along the western coasts, in the central and southern regions is explained by the predominance of westerly winds, driving surface layers of water away from the western coasts. Colder underlying waters rise to the surface. In addition, a cold current from the Gulf of Bothnia runs south along the Swedish coast.

Clearly expressed seasonal changes in water temperature cover only the upper 50-60 m; deeper, the temperature changes very little. In the cold season, it remains approximately the same from the surface to horizons of 50-60 m, and deeper down it decreases somewhat to the bottom.

Water temperature (°C) along a longitudinal section in the Baltic Sea

In the warm season, the increase in water temperature as a result of mixing spreads to horizons of 20-30 m. From here it drops abruptly to horizons of 50-60 m and then rises again slightly towards the bottom. The cold intermediate layer persists in the summer, when the surface layer warms up and the thermocline is more pronounced than in the spring.

Limited water exchange with the North Sea and significant river runoff cause low salinity. On the sea surface it decreases from west to east, which is associated with the predominant flow of river water into the eastern part of the Baltic. In the northern and central regions of the basin, salinity decreases slightly from east to west, since in the cyclonic circulation, salty waters are transported from south to northeast along the eastern coast of the sea further than along the western coast. A decrease in surface salinity can be traced from south to north, as well as in the bays.

In the autumn-winter season, the salinity of the upper layers increases slightly due to a reduction in river flow and salinization during ice formation. In spring and summer, surface salinity decreases by 0.2-0.5‰ compared to the cold half of the year. This is explained by the desalinating influence of continental runoff and spring melting of ice. In almost the entire sea, a significant increase in salinity from the surface to the bottom is noticeable.

For example, in the Bornholm Basin, salinity at the surface is 7‰ and about 20‰ at the bottom. The change in salinity with depth is essentially the same throughout the sea, with the exception of the Gulf of Bothnia. In the southwestern and partly central regions of the sea, it gradually and slightly increases from the surface to horizons of 30-50 m; below, between 60-80 m, there is a sharp layer of jump (halocline), deeper than which the salinity again increases slightly towards the bottom. In the central and northeastern parts, salinity increases very slowly from the surface to horizons of 70-80 m; deeper, at horizons of 80-100 m, a halo-wedge occurs, and then salinity increases slightly to the bottom. In the Gulf of Bothnia, salinity increases from the surface to the bottom by only 1-2‰.

In autumn-winter, the flow of North Sea waters into the Baltic Sea increases, and in summer-autumn it decreases somewhat, which leads to an increase or decrease in the salinity of deep waters, respectively.

In addition to seasonal fluctuations in salinity, the Baltic Sea, unlike many seas of the World Ocean, is characterized by significant interannual changes.

Observations of salinity in the Baltic Sea from the beginning of this century until recent years show that it tends to increase, against which short-term fluctuations appear. Changes in salinity in the sea basins are determined by the influx of water through the Danish Straits, which in turn depends on hydrometeorological processes. These include, in particular, the variability of large-scale atmospheric circulation. The long-term weakening of cyclonic activity and the long-term development of anticyclonic conditions over Europe lead to a decrease in precipitation and, as a consequence, a decrease in river flow. Changes in salinity in the Baltic Sea are also associated with fluctuations in continental runoff. With large river flows, the level of the Baltic Sea rises slightly and the waste flow from it intensifies, which in the shallow zone of the Danish Straits (the smallest depth here is 18 m) limits the access of salt water from the Kattegat to the Baltic. When river flow decreases, salty waters penetrate more freely into the sea. In this regard, fluctuations in the influx of salt water into the Baltic are in good agreement with changes in the water content of the rivers of the Baltic basin. In recent years, an increase in salinity has been observed not only in the bottom layers of basins, but also in the upper horizons. Currently, the salinity of the upper layer (20-40 m) has increased by 0.5‰ compared to the long-term average value.

Salinity (‰) along a longitudinal section in the Baltic Sea

Salinity variability in the Baltic Sea is one of the most important factors regulating many physical, chemical and biological processes. Due to the low salinity of the surface waters of the sea, their density is also low and decreases from south to north, varying slightly from season to season. Density increases with depth. In areas of distribution of salty Kattegat waters, especially in basins at horizons of 50-70 m, a permanent layer of density jump (pycnocline) is created. Above it, in the surface horizons (20-30 m), a seasonal layer of large vertical density gradients is formed, caused by a sharp change in water temperature at these horizons.

Water circulation and currents

In the Gulf of Bothnia and in the adjacent shallow-water area, a density jump is observed only in the upper (20-30 m) layer, where it is formed in the spring due to desalination by river runoff, and in the summer due to the heating of the surface layer of the sea. A permanent lower layer of density jump is not formed in these parts of the sea, since deep salty waters do not penetrate here and year-round stratification of waters does not exist here.

Water circulation in the Baltic Sea

The vertical distribution of oceanological characteristics in the Baltic Sea shows that in the southern and central regions the sea is divided by a density jump layer into upper (0-70 m) and lower (from 70 m to the bottom) layers. At the end of summer - beginning of autumn, when weak winds prevail over the sea, wind mixing extends to horizons of 10-15 m in the northern part of the sea and to horizons of 5-10 m in the central and southern parts and serves as the main factor in the formation of the upper homogeneous layer. During autumn and winter, with an increase in wind speeds over the sea, mixing penetrates to horizons of 20-30 m in the central and southern regions, and in the east - up to 10-15 m, since relatively weak winds blow here. As autumn cooling intensifies (October - November), the intensity of convective mixing increases. During these months, in the central and southern regions of the sea, in the Arkona, Gotland and Bornholm depressions, it covers a layer from the surface to approximately 50-60 m. Here thermal convection reaches its critical depth (for deeper propagation of mixing, salinization of surface waters due to ice formation is required ) and is limited by the density jump layer. In the northern part of the sea, in the Gulf of Bothnia and in the western Gulf of Finland, where autumn cooling is more significant than in other areas, convection penetrates to horizons of 60-70 m.

The renewal of deep waters and the sea occurs mainly due to the influx of Kattegat waters. With their active entry, the deep and bottom layers of the Baltic Sea are well ventilated, and with small amounts of salt water flowing into the sea at great depths, stagnation phenomena are created in the depressions up to the formation of hydrogen sulfide.

The strongest wind waves are observed in autumn and winter in open, deep areas of the sea with prolonged and strong south-west winds. Stormy winds of force 7-8 develop waves up to 5-6 m high and 50-70 m long. In the Gulf of Finland, strong winds in these directions form waves 3-4 m high. In the Gulf of Bothnia, storm waves reach a height of 4-5 m. The most large waves occur in November. In winter, with stronger winds, the formation of high and long waves is prevented by ice.

As in other seas of the northern hemisphere, the surface circulation of the Baltic Sea waters has a general cyclonic character. Surface currents are formed in the northern part of the sea as a result of the confluence of waters emerging from the Gulf of Bothnia and the Gulf of Finland. The general flow is directed along the Scandinavian coast to the southwest. Bending around on both sides. Bornholm, it is heading through the Danish Straits to the North Sea. On the southern coast, the current is directed to the east. Near the Gulf of Gdansk it turns north and moves along the eastern coast to about. Khnuma. Here it branches into three streams. One of them goes through the Irbe Strait into the Gulf of Riga, where, together with the waters of the Daugava, it creates a circular current directed counterclockwise. Another stream enters the Gulf of Finland and along its southern shore spreads almost to the mouth of the Neva, then turns to the northwest and, moving along the northern shore, leaves the gulf along with river waters. The third flow goes north and through the straits of the Åland skerries it enters the Gulf of Bothnia. Here the current along the Finnish coast rises to the north, goes around the northern coast of the bay and descends to the south along the coast of Sweden. In the central part of the bay there is a closed circular flow counterclockwise.

The speed of constant currents in the Baltic Sea is very low and is approximately 3-4 cm/s. Sometimes it increases to 10-15 cm/s. The current pattern is very unstable and is often disturbed by the wind.

The prevailing wind currents at sea are especially intense in autumn and winter, and during strong storms their speed can reach 100-150 cm/s.

The deep circulation in the Baltic Sea is determined by the flow of water through the Danish Straits. The inlet current in them usually extends to horizons of 10-15 m. Then this water, being denser, sinks into the underlying layers and is slowly transported by the deep current, first to the east and then to the north. With strong westerly winds, water from the Kattegat flows into the Baltic Sea along almost the entire cross-section of the straits. Eastern winds, on the contrary, strengthen the output current, which extends to horizons of 20 m, and only at the bottom the input current persists.

Due to the high degree of isolation from the World Ocean, tides in the Baltic Sea are almost invisible. Fluctuations in the tidal level at individual points do not exceed 10-20 cm. The average sea level experiences secular, long-term, interannual and intraannual fluctuations. They can be associated with changes in the volume of water in the sea as a whole and then have the same value for any point in the sea. Secular level fluctuations (in addition to changes in the volume of water in the sea) reflect vertical movements of the coast. These movements are most noticeable in the north of the Gulf of Bothnia, where the rate of land rise reaches 0.90-0.95 cm/year, while in the south the rise is replaced by a subsidence of the coast at a rate of 0.05-0.15 cm/year.

In the seasonal course of the Baltic Sea level, two minimums and two maximums are clearly expressed. The lowest level is observed in spring. With the arrival of spring flood waters, it gradually rises, reaching a maximum in August or September. After this the level decreases. A secondary autumn minimum is approaching. With the development of intense cyclonic activity, westerly winds push water through the straits into the sea, the level rises again and reaches a secondary, but less pronounced maximum in winter. The difference in level heights between the summer maximum and spring minimum is 22-28 cm. It is greater in the bays and less in the open sea.

Surge level fluctuations occur quite quickly and reach significant values. In open areas of the sea they are approximately 0.5 m, and at the tops of bays and bays they are 1-1.5 and even 2 m. The combined action of the wind and a sharp change in atmospheric pressure (during the passage of cyclones) cause seiche fluctuations in the level surface with a period of 24 -26 hours. Level changes associated with seiches do not exceed 20-30 cm in the open part of the sea and reach 1.5 m in the Neva Bay. Complex seiche level fluctuations are one of the characteristic features of the Baltic Sea regime.

Catastrophic St. Petersburg floods are associated with fluctuations in sea level. They occur in cases where the rise in level is due to the simultaneous action of several factors. Cyclones crossing the Baltic Sea from southwest to northeast cause winds that drive water from the western regions of the sea and push it into the northeastern part of the Gulf of Finland, where sea levels rise. Passing cyclones also cause seiche level fluctuations, which increase the level in the Åland region. From here, a free seiche wave, driven by westerly winds, enters the Gulf of Finland and, together with the surge of water, causes a significant increase (up to 1-2 m and even 3-4 m) in the level at its top. This prevents the flow of Neva water into the Gulf of Finland. The water level in the Neva is rapidly rising, which leads to floods, including catastrophic ones.

Ice cover

The Baltic Sea is covered with ice in some areas. Ice forms earliest (around the beginning of November) in the northeastern part of the Gulf of Bothnia, in small bays and off the coast. Then shallow areas of the Gulf of Finland begin to freeze. The ice cover reaches its maximum development in early March. By this time, motionless ice occupies the northern part of the Gulf of Bothnia, the Åland skerries area and the eastern part of the Gulf of Finland. Floating ice is found in open areas of the northeastern part of the sea.

The distribution of fixed and floating ice in the Baltic Sea depends on the severity of winter. Moreover, in mild winters, ice, having appeared, can completely disappear, and then appear again. In severe winters, the thickness of stationary ice reaches 1 m, and floating ice - 40-60 cm.

Melting begins in late March - early April. The sea is freed from ice from the southwest to the northeast.

Only in severe winters in the north of the Gulf of Bothnia can ice be found in June. However, the sea is cleared of ice every year.

Economic importance

In the significantly desalinated waters of the bays of the Baltic Sea, freshwater fish species live: crucian carp, bream, chub, pike, etc. There are also fish here that spend only part of their life in fresh waters, the rest of the time they live in the salt waters of the sea. These are now rare Baltic whitefish, typical inhabitants of the cold and clean lakes of Karelia and Siberia.

A particularly valuable fish is Baltic salmon, which forms an isolated herd here. The main habitats of salmon are the rivers of the Gulf of Bothnia, the Gulf of Finland and the Gulf of Riga. She spends the first two to three years of her life mainly in the southern part of the Baltic Sea, and then goes to spawn in rivers.

Purely marine fish species are common in the central regions of the Baltic, where salinity is relatively high, although some of them also enter rather desalinated bays. For example, herring lives in the Gulf of Finland and the Gulf of Riga. More salty water fish - Baltic cod - do not enter desalinated and warm bays. The eel is a unique species.

In fishing, the main place is occupied by herring, sprat, cod, river flounder, smelt, perch and various types of freshwater fish.

The Baltic Sea is the northern marginal body of water in Eurasia. It cuts deep into the land, and due to this it belongs to internal water flows. The sea fills the waters of the Atlantic. It is located in Northern Europe. The Baltic countries have access to the Baltic Sea. And also such states as: Denmark, Sweden, Finland, Germany, Russia and Poland. The stream connects to the ocean through the system and the North Sea.

The area of ​​the reservoir is about 415 thousand square km. The volume of the water surface is more than 20 thousand cubic meters. km. The deepest trench is 470 meters.

Hydrology

The Baltic Sea, whose salinity greatly affects flora and fauna, is filled with a huge amount of fresh water. Their constant source is precipitation. Salty streams penetrate the reservoir through bays and tributaries. Tides have insignificant levels and, as a rule, their magnitude is no more than 20 cm.

Constantly located within a radius of one mark. Air masses can have a strong influence on it. Along the coast, the water level can rise up to 50 cm, in narrower places - up to 2 meters.

There are practically no storms on the water stream. Like other seas washing Russia, the Baltic reservoir is calm, and rarely its waves can reach a height of 4 meters. It is most stormy in the fall, in November. Maximum fluctuations are 7-8 points. In winter they practically stop, which is facilitated by ice.
The constant current of the Baltic Sea is small. Within 10-15 cm/s. The maximum current increases during storms to 100-150 cm/s.
The tides of the Baltic Sea are almost invisible. This is facilitated to a greater extent by the isolation of the water flow. Their level varies within 20 meters. The maximum increase in water level is in August and September.

A significant part of the coast is covered with ice from October to April. The southern part and center of the sea, but glaciers can drift along them during the thawing period (June-August).

The Baltic Sea is rich in natural resources. Oil reserves lie here and new fields are being developed. Large deposits of amber have also recently been discovered. The Nord Stream gas route runs along the bottom of the sea.

The Baltic Sea is also rich in fish and seafood. In recent years, the ecology of the stream has deteriorated significantly. The waters become clogged with toxins coming from large rivers. The presence of chemical weapons dumps is also recorded.

Due to the shallow depth of the sea, shipping here is not very developed. Only light vessels are able to cross the watercourse without problems. The largest ports of the Baltic Sea: Vyborg, Kaliningrad, Gdansk, Copenhagen, Tallinn, St. Petersburg, Stockholm.

The waters of this reservoir are unsuitable for the development of resort tourism, but nevertheless there are sanatoriums and hospitals on the coastal part. These are the Russian resort cities of Svetlogorsk, Zelenogorsk, Sestroretsk, Latvian Jurmala, Lithuanian Neringa, Polish Koszalin and Sopot, German Albeck and Binz.

Brief description of water temperature and sea salinity

In the central part of the Baltic Sea, as a rule, the temperature rarely exceeds 15-18 o C. At the bottom it is about 4 degrees. The bay often experiences calm weather and +9..+12 o C.

The Baltic Sea, whose salinity decreases in the direction from west to east, has an official indicator of 20 ppm at the beginning of the current. At depth this figure increases by 1.5 times.

Name

For the first time, the etymological name “Baltic” is found in a historical treatise of the 11th century. The earlier name of the sea was Varangian. This is what is mentioned in the famous “Tale of Bygone Years”.

Extreme points

Extreme points of the Baltic Sea:

  • southern - Wismar (Germany), coordinates - 53° 45` N. sh.;
  • northern - Arctic Circle coordinates - 65° 40` N. sh.;
  • eastern - St. Petersburg (Russia), coordinates - 30° 15` east. d.;
  • western - Flensburg (Germany), coordinates - 9° 10` E. d.

Geographical characteristics: territory, tributaries and bays

The Baltic Sea (salinity and its characteristics are described below) extends from southwest to northeast for 1360 km. The greatest width is located between the cities of Stockholm and St. Petersburg. It is 650 kilometers.

According to historical information, the Baltic Sea has existed for about 4 thousand years. During the same period of time, the Neva (74 km), which flows into this body of water, begins to exist. In addition to it, more than 250 rivers merge with the stream. The largest of them are Vistula, Oder, Narva, Neman, Western Dvina.

Some ports of the Baltic Sea lie on its large bays. In the north is the Gulf of Bothnia, the largest and deepest. In the east - Riga, located between Estonia and Latvia, Finnish, washing the shores of Finland, Estonia, Russia, and Due to the fact that the latter is separated from the sea by a sand spit, the water in the stream is almost fresh. This is a unique feature.

The average depth of the Baltic Sea is 50 meters, the bottom is entirely within the mainland. This nuance makes it possible to classify it as an inland continental reservoir.

Islands

In the sea area there are more than 200 islands of different sizes. They are located unevenly both near the coast and far from them. The largest Baltic islands are Zealand, Falster, Møn, Langeland, Lolland, Bornholm, Funen (belonging to Denmark); Öland and Gotland (Swedish islands); Fehmarn and Rügen (belongs to Germany); Hiiumaa, Saaremaa (Estonia).

Coastline

The Baltic Sea (the ocean strongly influences it with its waters) has a different coastline along the entire perimeter of the waters. In the northern part, the bottom is uneven and rocky, and the coast is indented with small bays, ledges and small islands. The southern part, on the contrary, has a flat bottom and a low-lying coast, with a sandy beach, which in some areas is represented by small dunes. A frequent occurrence on the young coast are sand spits cutting deep into the sea.
The sedimentary bottom is represented by green, black silt (of glacial origin) and sand, and the soil consists of stones and boulders.

Salinity and its regular changes

Due to the large amount of precipitation and powerful water runoff from rivers, the Baltic Sea (the salinity of the reservoir is relatively low) is filled with excess fresh water. It is distributed unevenly. Where the Baltic reservoir enters deep into the shore, the water is almost fresh, and its salinity is influenced by the North Sea. This situation is not permanent. Storm winds contribute to water mixing.
Based on this, the salinity of the Baltic Sea is low. A decrease in its level is typical for the coastline; the highest number of ppm is at the bottom.
In the area where the watercourse meets the straits in the west, the water salinity is up to 20 ‰ on the sea surface, and at the bottom - 30 ‰. Off the coast of the Gulf of Bothnia and the Gulf of Finland, the indicator is the lowest. It does not exceed 3 ‰. Levels from 6 to 8‰ are typical for the waters of the central part.

Seasonality also affects the distribution of salinity in the Baltic Sea waters. So, in the spring-summer season it decreases by 0.5-0.2 ppm. This is due to the fact that melted rivers carry fresh water to the sea. In autumn and winter, on the contrary, it increases due to the arrival of cold northern masses.

Changes in sea salinity are one of the important reasons that regulate biological, physical and chemical processes on the shore. Partly due to the freshness of the water, the shore has a loose structure.

Similar articles