The geographic position of the Baltic Sea. Baltic Sea: salinity, depth, coordinates, description

23.09.2019

The Baltic Sea is a sea located in Northern Europe, inland and belongs to the basin of a huge Atlantic Ocean.

Origin

The Baltic Sea lies on the stable Russian tectonic plate, the formation of which ended approximately 1.8-2 billion years ago.

30 million years ago, the plate took the position on which it is held now. During the long ice age, which began about 700 million years ago, the entire territory of Northern Europe was covered with a thick layer of ice and snow.

Huge ice masses caved in the continental rock - thus creating a "hollow" for the future sea. And when the last ice age came to its end - two tens of millennia BC, all the ice melted and the Baltic Sea formed in their place.

The formation of the modern Baltic Sea took place in several stages, which should be discussed in more detail. First, the so-called Baltic glacial lake was formed, which happened fourteen thousand years BC. And ten thousand years BC, through the strait in Sweden, the territory of the modern sea was filled with sea water - this is how the Yoldievsky was formed.

Baltic Sea. storm photo

The Ancyl Sea dates back to 9-7, 5 millennia - when access to the world's oceans was closed. Around the middle of the eighth millennium, the sea merged with the ocean due to the rise in ocean levels, which formed the Lothyron Sea. And the modern Baltic Sea appears approximately in the fourth millennium BC.

Characteristic

The area of the Baltic Sea, excluding the islands, reaches 415 thousand square kilometers. But the volume of water for a rather large sea reaches only 21, 5 thousand cubic kilometers. Consequently, the depth of the Baltic Sea is shallow. The average depth revolves around 50 meters, and the greatest depth is only half a kilometer. The coastline is approximately eight thousand kilometers long.

The climate of the sea is temperate maritime, influenced by the Atlantic Ocean, from where cyclones with westerly winds come. Precipitation often falls, fog appears, especially in winter and spring. Storms are rare, and the wave height is not higher than 4 meters. Tides are almost invisible, usually no more than 20 centimeters.

Baltic Sea Kaliningrad Region photo

In summer, the water temperature reaches an average of about eighteen degrees Celsius. In winter, and especially in February, it can reach zero levels. Coastal waters are frozen in the east and north, the southern and central parts of the sea are open. Only if the winter is very cold, then the entire Baltic Sea is covered with ice, but this rarely happens.

For the most part, the salinity of the sea is extremely low (7 - 20 ppm), since many freshwater rivers flow into the sea. In turn, this has served the modest species diversity of the local flora and fauna. However, low salinity plays an important role for humans. At critical moments, water can be directly from the sea - but not for too long.

Unlike other seas, the Baltic can give you a source of water for a short time, which can even save your life. But the constant and long-term drinking of such water can be harmful to your health.

What rivers flow into the Baltic Sea

The following flows into the Baltic Sea big rivers which are also of great importance for industry and infrastructure:

Western Dvina,
Neva,
Venta,
Pregolya, Narva,
Oder
Vistula.

The relief of the Baltic Sea

As already mentioned, the average depth of the seabed reaches fifty meters, since the sea is part of the continental shelf itself. At the bottom of the sea there are several hollows and the depth of most of them hardly reaches two hundred meters, but the deepest of them goes down to 470 meters.

Baltic sea in winter photo

In the southern part of the sea, the bottom is flat, while in the north it is predominantly rocky.

Cities

Among the big cities on the Baltic Sea are St. Petersburg, Klaipeda, Svetlogorsk and Zelenogradsk, Jurmala, Parnu and Narva, Albek, Bints and many others. All of them have become either favorite places for tourists or just resort towns where hundreds of thousands of people come to rest every year.

Animal world

The Baltic Sea is a very important industrial base, as it is the source of a huge amount of industrially important fish species. The very species diversity in the world of fish is small, but the number of representatives of each species is impressive. The small variety of fish is due to the fact that the water in the sea is mostly fresh, and there are not so many freshwater fish.

Svetlogorsk Kaliningrad region photo

In areas where there is more salt water, the species diversity is somewhat greater, but still remains rather poor. At the very bottom of the sea, flounders and gobies live, as well as several species of molluscs and small crustaceans. In addition to them, worms also live on the seabed. There are several types of jellyfish in the Baltic Sea, among which there are quite huge ones.

Of the small fish, schooling Baltic sprats and three-spined sticklebacks can be noted. In areas with predominantly fresh water, such river fish species as pike, perch, pike perch, roach, bream, burbot, whitefish, ide and some others, less common, live. Valuable industrial fish live in the Baltic Sea on a huge scale, and they include sprat, herring (makes up about half of the total catch in the Baltic Sea), flounder, salmon, cod and eel.

seal in the baltic sea photo

Seals in the Baltic Sea are represented by only three species, including the gray seal, the common seal pig or just the common seal. Sharks also live in the sea, although they are represented by only one species that does not pose a danger to humans - these are small katrans. In rare regions, it is very rare to find the more dangerous herring shark.

The northernmost point of the Baltic Sea is located as far as the North Pole;
The Slavs, at the time of Russia, called the sea Varangian, and all the inhabitants who sailed because of it - the Varangians;
The Nord Stream gas pipeline was laid between Germany and Russia, which is located at the very bottom of the Baltic Sea;
The Baltic Sea is also a huge base for oil production, which is now being implemented by the government of the Russian Federation;
The Baltic Sea is very heavily polluted with chemical waste, which is why the fish population is declining.

ENE material

Baltic Sea map.

Baltic Sea

Baltic Sea (BESBE)

Remarkable is the change in the boundaries of the sea and the mainland on the Baltic Sea; it recedes from both shores of the Gulf of Finland and Bothnia (usually they take 1.2 to 1.6 m per century for the northern shores of Finland and 0.6 m for the southern ones), and on the southern shores of Sweden and on the shores of Kurish Gaffa, on the contrary, it floods the coast.

In terms of salt content, the Baltic Sea is the most freshwater of all seas, which depends on the flow of up to 40 fresh water rivers into it. According to the salt content, B. m. Is divided into 3 regions: the first region includes the Gulfs of Bothnia, Finland, and Riga, and the second region includes the middle body of water up to the Prussian coast and the meridian of the southern tip of Sweden; to the third - the western, narrow continuation of the sea to the Belts. In the northern part of the Gulf of Bothnia, the water is almost fresh (0.26 - 0.39%); in the Kvarken Strait, you can even drink it. IN Gulf of Finland from the mouths of the Neva to Kronstadt, the water is also almost fresh (about 0.35%). Beyond Kronstadt, the water is already salty, but up to the island of Hochland it is still used for drinking. In the Gulf of Riga, the salt content is not constant, which depends on the direction of the winds (near the mouth of the Dvina - 0.58%). In the second area, the salt content fluctuates between 6 and 11 per. In the third region of the Baltic Sea, the salt content depends on whether the current flows from the Kategat to the Baltic Sea or vice versa. Wave in the Baltic Sea, no more than 1.5 meters in height and 9 - 12 meters in width. The waves of the sea are least noticeable with a northeasterly wind. There are almost no ebb and flow.

Due to its low salt content, shallow depth and severity of winter, the Baltic Sea freezes over a large area, although not every winter. So, for example, travel on ice from Reval to Helsingfors is not possible every winter, but in severe frosts and deep straits between the Aland Islands and both coasts of the mainland are covered with ice, and in the city of the Russian army with all military weights passed here to the ice to Sweden and in 2 other places across the Gulf of Bothnia. In the city of Sweden, King Karl X crossed the ice from Jutland to Zeeland. In the more open part of the sea, ports that are not too protected do not freeze over every winter, and in any case usually only for a few days, for example, within Russia, especially Libau and Vindava, somewhat more ice usually remains in the Baltic port and Gangeuda, for more Revel, Pernov, Riga, even farther in the mouths of the Neva and the eastern part of the Gulf of Finland, and especially in the northern part of the Bothnian. Below are data on the duration of freezing of the sea and the lower reaches of the rivers flowing into it:

Latitude.			Number of days under ice.
54 °	The mouth of the r. Herbs at Lubeck		32
54 °	Greifswald Bay		58
57 °	Gulf of riga	near Ahrensburg	149
58 °		at Pernov	135
57 °		near Tserelsk. lighthouse	40
57 °	Western Dvina	near Riga	121
	Western Dvina	Oriental	165
60 °	Kronstadt raids	Small	153
	Kronstadt raids	Large	162
60 °	Neva in St. Petersburg		147
60 °	Internal raid near the Ganges		86
65 °	Ulea at Uleoborg		175

Average air temperatures:

	Of the year	January	April	July	October
Copenhagen	7,4	0,1	5,7	16,6	8,2
Koenigsberg	6,6	3,1	5,6	17,3	8,0
Libava	6,6	3,2	4,2	16,9	8,4
Mitava	6,4	5,0	4,9	17,6	6,9
Baltic port	4,6	5,4	1,6	16,1	6,3
Revel	4,4	6,4	1,5	16,6	5,9
Petersburg	3,7	9,4	2,1	17,8	4,5
Helsingfors	3,9	6,9	1,0	16,4	5,6
Ganges	4,4	4,3	0,4	15,5	6,4
Torneo	0,3	12,3	1,5	15,5	1,3

Novgorod was in lively relations with the Hansa. A little later the Hansa began the military and commercial predominance of Denmark in the Baltic Sea. At the end of the XVI and before the beginning of the XVIII century. the trade route through the Gulf of Finland and the Neva lost its significance. Thanks to the wars, the defeat of Novgorod by Ivan the Terrible, the enmity towards Russia of Sweden and the German Order, Russia's foreign sea trade went mainly through Arkhangelsk. The founding of St. Petersburg by Peter the Great, the transfer of the capital here and the installation of canals connecting the regions of rivers flowing into the Gulf of Finland with the Volga region raised trade in the mouths of the Neva to an unprecedented height. The construction of railways was also very important, especially the Nikolaev, Moscow-Ryazan and Ryazan-Kozlovskaya. But others railways then they began to divert cargo from St. Petersburg, partly to more convenient and less long time freezing Russian ports (Revel, Riga, Libau), partly abroad, to Konigsberg.

Currently on import Petersburg with Kronstadt nevertheless remains decisively the first port of the Baltic Sea; in general, the most important ports of the Baltic Sea - 10; in Russia: Petersburg, Revel, Riga, Libava; in Germany: Pillau (port of Konigsberg), Danzig, Stetin and Lubeck; in Denmark - Copenhagen, in Sweden - Stockholm. None of these ports, however, have the same turnovers as London, Liverpool, Hamburg, Antwerp and New York. Of the minor ports, one can also name in Germany: Flensburg, Kiel, Wismar, Rostock, Stralsund, Elbing and Memel; in Russia: Vindavu, Arensburg, Pernov, Baltic port, the mouth of the Narova, Vyborg, Helsingsfors with Sveaborg, Gange, Abo, Uleaborg; in Sweden: Istod and Visby. The delivery and release of goods has changed in the following sizes since the 40s.

Russian ports without Finland.

	Average export.			Average delivery.
	1840-49	1850-60	1888	1840-49	1850-60
	In thousands of rubles.
Petersburg and Kronstadt	83485	34408	84240	43378	62386	61920
Revel	285	468	20723	495	700	41873
Riga	13253	14303	53806	4239	4109	22189
Libava	743		51236	140	164	24234

This shows that the trade of all ports has increased, but Revel and Libava to a much greater extent than Petersburg and Riga. The very large import of Revel is explained by the fact that it serves as a winter port for St. Petersburg. The main export items of the Baltic ports are bread in grain, especially rye and oats, flax and hemp, flaxseed, and timber. Privoz - tea, cotton, wine, expensive manufactured goods and, until very recently, all kinds of iron, from cast iron to machinery, inclusive.

Literature:

"Lotsiya" (published by the Hydrographic Department, also published by him maps and atlases);
Segelhandb. für die Ostsee "; (Berlin, 1878);
Jahresb. des Komission zur Untersuch, der deutsch. Meere "(since 1873);
Ackerman, “Phys. geogr. des Ostsee "(Hamburg, 1883);
Stuckenber, “Hydr. des russ. Reiches, vol. I;
Nebolsin, “Review of the external. trade of Russia ”(published by the Dep. there. collection);
Veselovsky, "The Climate of Russia" (1857);
Voeikov, Climates of the Globe (1884).

Baltic Sea (addition to the article)

(cm.). Bottom relief. Depths of more than 200 m lie to the north from the Gotland Island (naib. Depth 325 m) and to the east from the same island (naib. Depth 255 m). Between Oland Island (at the beginning of the Gulf of Bothnia) and west. depths of more than 200 m are also found along the coast. Depths of more than 100 m lie to the E of Bornholm Island, to the southeast of the sea in the Danzig Bay, then in the central part of the B. 59 ° turns to the Gulf of Finland, gradually narrowing, and ends on the line Gangaudd - Baltic port. It is in this hollow that the aforementioned depression up to 255 m is located. Depths of more than 100 m are also found in the Bothnian Hall. to the west of Olanda Island, between 61 ° and 63 ° 15 ", and in the northerly part between 64 ° and 65 °. At 63 ° parallel, near the western coast, there is a small pit with a maximum depth of 272 m. the sea depths are insignificant (up to 20 m).

Priming on the deep places The Baltic Sea exclusively consists of brown or gray, soft silt or hard clay, and on the banks and in the coastal strip there is always fine sand of white or yellow color, or brown sand with gravel. At the bottom, especially in the area of the skerries, there are many stones.

Temperature water on the surface of the B. sea follows the air temperature, and the first on average exceeds the second by ½ °. From August to March, the sea surface is warmer than the air, from April to July the air is warmer. The highest average monthly rate. in winter (February) are observed in the west. parts of the sea (2.8 °). Average February pace. the surface of the south. parts of the B. Sea 1.5 °; pace. generally decreases in the direction from W to V. August temperatures by 3 approx. 16-17 °, at German stations about 18 °, in the throat of the Gulf of Finland 16-17 ° (Reval). As for the temperatures at depths, judging by the observations at the Danish stations, from October to March the rate. increases with depth, and decreases from April to August. Changing temp. to depth. 8 m is quite the same at all stations, while at other stations the rate is. very different depending on the bottom topography. Minimum temp. (3 ° - 5 °) in low layers occurs in March, maximum at the bottom (12 ° - 16 °) in September and in some places in October. The magnitude of the fluctuations decreases with depth. With onshore winds, sometimes in the hottest time the pace. water on the surface drops by several degrees, especially in those places where the depths increase gradually. The reason for this phenomenon is that driven by the wind warm water is replaced by a cold protruding from below. Falls from 20 ° to 6 ° were observed.

Currents. A large number of rivers bring to the B. sea a mass of fresh water, which at all seasons of the year maintains an excess of water gain over the loss through evaporation; lighter surface fresh water from the B. Sea flows into the German through the straits, while the saltier heavy water of oceanic origin moves at depths through the straits into the B. Sea; Having passed mainly through the Great Belt, this water partly spills into the Kiel Bay., increasing the degree of salinity in it, partly passes to the shores of Mecklenburg. Due to the spread over a large area, the saline current loses its strength and it is difficult to trace it further. Correct observations of the currents, carried out at the floating lighthouse "Adler-Grunt", revealed a great variability of surface currents in the south-west. parts of the B. sea depending on the winds. This influence is detected very quickly to a depth of 5 m, so that with a significant change in wind from one day to another, the course of the second day almost always corresponded more to the wind blowing at that time than the wind of the previous day. In general, with a wind of sufficient strength, the current is always directed downwind with a deviation of about 2½ points from the wind.

Salinity The sea's B. decreases from west to east and from the bottom to the surface. Due to the large inflow of fresh water in spring and summer, it decreases in the surface layers at this time; in zap. part of the B. sea, it decreases much faster than in the east. In the Fehmarn hall. to the south of Laaland Island on the surface salinity is 1%, at depths of 30 m it was found up to 2.956%; east of the Falster-Darserort line on great depths- less than 2%, east of Gotland Island on the surface - 0.71% at a depth of 59 m 1.72%, at a depth of 100 m 1%, at a depth. 200 m 1.16%. At the entrance to the Finnish Hall. surface salinity 0.69%, at Seskar 0.35%, in the Riga Bay. 0.57%, in the south. parts of the Bothnian Hall. 0.77-0.437%, from this hall. 0.39-0.26%.

Level fluctuations B. the seas have a correct course during the year. The highest level is in August, after which it decreases until November, rises slightly in December, but then decreases until April, after which the increase begins again. The annual amplitude in Kronstadt (46 years of observation) is 9.5 inches, in Swinemunde (southwestern part of the sea, 78 years of observation) is about 5 inches. On temporary water rises off the coast big influence winds exert, and the rise of water sometimes precedes the wind. O and NO winds raise water off the coast of Holstein and Mecklenburg and drive off the shores of Courland and east. Prussia. W vice versa; in addition, the W is pumping water into the Finnish Hall. S drive water partly through the Sound and Belts to the Kattegat, partly on the C to the Bothnian Hall. Winds often produce devastating floods in the low-lying south. the shores of the B. Sea and in the Finnish Hall.

Ebb and flow in the Baltic Sea are insignificant and decrease towards B: in Skagen the tide height is 0.28 m, in Kiel 0.07 m, in Swinemunde 0.011 m, in Pilau - 0.006 m and in Memel 0.005 m

The article reproduces material from the Great Encyclopedic Dictionary of Brockhaus and Efron.

Baltic Sea (ITU)

Baltic Sea. Map from ITU

Baltic Sea, inland sea in the North. Europe, with gulfs (Bothnian, Finnish and Riga), jutting far into the mainland and connecting. with the German Sea Sound, Big and Small Belts, Skagerrak, Kattegat, as well as arts. Kiel Canal (see map, art. 567-68). - 406.720 km 2. Numerous islands: Danish Islands, Bornholm, Oland, Gotland, Ezel, Dago, Aland Islands, etc. The average depth is 55 m, the greatest is 463 m south of Stockholm. The bottom relief is restless. Due to the abundant inflow of water from the flowing rivers (Oder, Vistula, Neman, Western Dvina, Neva, etc.), the Baltic Sea is highly desalinated, salinity is from 0.3 to 1.5%. The ebb and flow are insignificant and almost imperceptible: in the Great Belt about 30 cm, in the very B. m. Even less - about 10 cm. The bays freeze annually: the Bothnian and Finnish - for 6 months, Riga - for 125 days, near Kiel - for 35 days. The open sea is covered with ice only in extremely harsh winters.

Fishing is significant; commercial fish are caught herring, sprat, flounder, salmon, etc. The busiest ports are: Stettin, Lubeck, Kiel, Koenigsberg (Germany), Danzig (free city), Copenhagen (Denmark), Malmo, Stockholm (Sweden), Memel, he Klaipeda (Lithuania), Libava, Riga (Latvia), Revel, aka Tallinn (Estonia), Abo, Helsinki, aka Helsingfors (Finland), Kronstadt, Leningrad (RSFSR).

The article reproduces the text from the Small Soviet Encyclopedia.

Baltic Sea (TSB)

Baltic Sea(late lat. mare Balticum), among the ancient Slavs - Varangian sea.

Physico-geographical sketch.

General information.

The Baltic Sea - the Mediterranean (inland) sea of the Atlantic Ocean, juts deep into the continent of Europe. It connects with the North Sea by the Oresund (Sound), B. and M. Belty, Kattegat and Skagerrak straits. Washes the shores of the USSR, Poland, East Germany, Germany, Denmark, Sweden and Finland. Sea border The Baltic Sea passes through the southern entrances of the Øresund, B. and M. Belty straits. Area 386 thous. km 2. Average depth 71 m. Average volume of water 22 thous. km 3. The shores of the Baltic Sea in the south and south-east. mostly low-lying, sandy, lagoon type; from the land side - dunes covered with forest, from the sea side - sandy and pebble beaches. In the north, the shores are high, rocky, predominantly skerry. Coastline strongly indented, forms numerous bays and bays.

The largest bays: Bothnian (according to physical and geographical conditions it is a sea), Finnish, Riga, Curonian, Gdansk Bay, Szczecin, etc.

Baltic Sea. Shore Danish island Bornholm.

Islands B. m. Of continental origin. There are many small rocky islets - skerries located along the northern shores and concentrated in groups of Vasi and Åland Islands... Most large islands: Gotland, Bornholm, Sarema, Muhu, Hiuma, Oland, Rügen, etc. A large number of rivers flow into the Baltic Sea, the largest of which are the Neva, Western Dvina, Neman, Vistula, Odra, etc.

Geological structure and bottom topography. The Baltic Sea is a shallow shelf sea. Depths of 40-100 prevail. m. The shallowest areas are the Kattegat straits (average depth 28 m), Øresund, B. and M. Belty, the eastern parts of the Gulf of Finland and Bothnia and the Gulf of Riga. These areas of the seabed have a leveled accumulative relief and a well-developed cover of loose sediments. Most of the bottom of the Baltic Sea is characterized by a highly dissected relief; there are relatively deep basins: the Gotland (249 m), Bornholm (96 m), in the Sodra-Kvarken Strait (244 m) and the deepest - Landsortsjupet to the south of Stockholm (459 m). There are numerous stone ridges; in the central part of the sea, there are ledges - continuation of the Cambrian-Ordovician (from the northern coast of Estonia to the northern tip of Öland Island) and Silurian clays, underwater valleys, glacial-accumulative relief forms flooded by the sea.

The Baltic Sea occupies a depression of tectonic origin, which is a structural element of the Baltic shield and its slope. According to modern concepts, the main irregularities of the sea bottom are due to block tectonics and structural-denudation processes. The latter, in particular, owe their origin to the underwater cliff ledges. The northern part of the seafloor is composed mainly of Precambrian rocks, overlapped by an intermittent cover of glacial and recent marine sediments.

In the central part of the sea, the bottom is composed of Silurian and Devonian rocks, hidden to the south under a layer of glacial and marine sediments of considerable thickness.

The presence of underwater river valleys and the absence of marine sediments under the stratum of glacial deposits indicate that in the preglacial time, there was dry land in the place of the B. m. During at least the last glacial epoch, the basin of the B. m. Was completely occupied by ice. Only about 13 thousand years ago there was a connection with the ocean, and sea waters filled the cavity; the Yoldian Sea was formed (according to the mollusk Joldia). The phase of the Yoldian Sea was preceded somewhat earlier (15 thousand years ago) by the phase of the Baltic glacial lake, which had not yet communicated with the sea. About 9-7.5 thousand years ago, as a result of tectonic uplift in Central Sweden, the connection between the Yoldian Sea and the ocean ceased, and the B. m. Again became a lake. This phase of the development of B. m. Is known as Lake Ancylovo (according to the mollusk Ancylus). A new sinking of land in the area of modern Danish straits, what happened about 7-7.5 thousand years ago, and an extensive transgression led to the renewal of communication with the ocean and the formation of the Litorina Sea. The level of the last sea was several meters higher than the present one, and the salinity was higher. Deposits of the Littorina transgression are widely known on the present-day coast of the Baltic Sea.The secular uplift in the northern part of the B.M basin continues even now, reaching the Gulf of Bothnia in the north. m over a hundred years and gradually decreasing to the south.

Climate The Baltic Sea is maritime temperate, strongly influenced by the Atlantic Ocean. It is characterized by relatively small annual temperature fluctuations, frequent precipitation, fairly evenly distributed throughout the year, and fogs during cold and transitional seasons. During the year, westerly winds prevail, which are associated with cyclones coming from the Atlantic Ocean. Cyclonic activity reaches its highest intensity in the autumn-winter months. At this time, cyclones are accompanied by strong winds, frequent storms and cause large rises in the water level off the coast. In the summer months, cyclones weaken and their frequency decreases. The invasion of anticyclones is accompanied by winds from the east.

B.'s stretch of m by 12 ° along the meridian determines noticeable differences climatic conditions its separate areas. The average air temperature in the southern part of Bulgaria is -1.1 ° C in January and 17.5 ° C in July; middle part: in January -2.3 ° C, July 16.5 ° C; Gulf of Finland: in January -5 ° C, in July 17 ° C; northern part of the Gulf of Bothnia: -10.3 ° C in January, 15.6 ° C in July. Cloudiness in summer is about 60%, in winter more than 80%. Average annual precipitation in the north is about 500 mm, in the south over 600 mm, and in some areas up to 1000 mm. The largest number of foggy days falls on the southern and middle part of the B. m., Where on average it reaches 59 days a year, the smallest - in the north of the Gulf of Bothnia (up to 22 days a year).

The hydrological conditions of B. m. Are determined mainly by its climate, an excess of fresh water, and water exchange with the North Sea. Excess fresh water equal to 472 Km 3 per year, formed due to continental runoff. The amount of water entering the precipitation (172.0 Km 3 per year) is equal to evaporation. Water exchange with the North Sea averages 1659 Km 3 in year ( salty water 1187 Km 3 per year, fresh - 472 Km 3 in year). Fresh water a drainage current leaves the Baltic Sea for the North Sea, a saline current flows through the straits from the North Sea to the Baltic Sea in a deep current.Strong westerly winds usually cause an inflow, and easterly winds - a runoff of water from the Baltic Sea through all sections of the Øresund Strait , B. and M. Belty.

The B.'s currents of m form a counterclockwise circulation. Along south coast the current is directed to the east, along the east - to the north, along the west - to the south, and near the northern coast - to the west.The speed of these currents ranges from 5 to 20 m / sec. Under the influence of winds, currents can change direction and their speed near the coast can reach 80 cm / sec and more, and in the open part - 30 cm / sec.

The surface water temperature in August is 15 ° C, 17 ° C in the Gulf of Finland; in the Gulf of Bothnia 9 ° C, 13 ° C and in the central part of the sea 14 ° C, 18 ° C, and in the south it reaches 20 ° C. In February - March, the temperature in the open sea is 1 ° С-3 ° С, in the Bothnian, Finnish, Riga and other bays and bays below 0 ° С. The salinity of surface water rapidly decreases with distance from the straits from 11 ‰ to 6-8 ‰ (1 ‰ -0.1%) in the central part of the sea. In the Gulf of Bothnia, it is 4-5 ‰ (in the north of the gulf, 2), in the Gulf of Finland, 3-6 ‰ (at the top of the gulf, 2 ‰ and less). In the deep and bottom layers of water, the temperature is 5 ° C or more, and salinity varies from 16 ‰ in the west to 12-13 ‰ in the central part and 10 ‰ in the north of the sea. In the years when the inflow of water increases, salinity rises in the west to 20 З, in the central part of the sea to 14-15 ‰, and in the years when the inflow decreases, in the middle parts of the sea to 11 ‰.

Fauna The Baltic Sea is poor in species, but rich in quantity. The brackish-water race of Atlantic herring (Baltic herring), Baltic sprat, as well as cod, flounder, salmon, eel, smelt, vendace, whitefish, and perch live in B. m. Mammals include the Baltic seal. Intensive fishery is conducted in B.M.

Research history.

Russian hydrographic and cartographic work began in the Gulf of Finland at the beginning of the 18th century. In 1738, F.I.Soimonov published an atlas of bourgeoisie, compiled from Russian and foreign sources. In the middle of the 18th century. many years of research in B. m. were carried out by A. I. Nagaev, who made a detailed navigation. First deep-sea hydrological research in the mid-1880s. were performed by S.O. Makarov. Since 1920, hydrological work was carried out by the Hydrographic Department, the State Hydrological Institute, and after Patriotic War 1941-45, extensive comprehensive research was launched under the leadership of the Leningrad branch of the USSR State Oceanographic Institute.

Yu.D. Mikhailov, O.K. Leont'ev.

Historical sketch., Volin, Novgorod, Gdansk and others. The offensive in the 12-13 centuries. German, Danish, and Swedish feudal lords in the Baltic region, the seizure of the southeastern coast of the Baltic Sea by the Teutonic Order dealt a serious blow to the positions of the Slavic states on the Baltic Sea. the dominant role in Baltic trade began to be played by the North German Hansa and its main center, Lübeck (especially after the victorious war of the Hansa against Denmark, which previously had dominion over the trade route between the Northern and Burma Mt.). The value of B. m. As the main waterway through which contacts were made between the Eastern and Western Europe(in the north of the mainland), became especially great in the 16-17 centuries. due to the growing role of trade in economics and politics European states... A struggle for hegemony in the Baltic Sea unfolded between the Eastern European powers (“ Dominium maris Baltici"In Latin, the diplomatic language of that time), which played a major role in the pan-European and regional conflicts of that time - in the Livonian War of 1558-83 (which was an important stage of the Russian state's struggle for access to B. m.), In numerous Danish Swedish and Polish-Swedish wars and in Thirty Years' War 1618-18. As a result of these wars from the middle of the 17th century. Swedish hegemony was established in the Baltic Sea. Russia's victory over Sweden in the Northern War of 1700-21 provided Russia with access to the Baltic Sea and its hegemony in the Eastern Baltic. Russia took possession east coast B. m. With the most important ports of Revel (Tallinn), Narva, Riga, the Vyborg fortress, and others; Petersburg, founded in 1703, soon became the country's main foreign trade port on the B. m., Kronstadt became the main naval fortress and the main base of the first Russian Baltic Fleet. Since the end of the 19th century. On the Baltic Sea, the positions of Germany were significantly strengthened, which created here a strong navy and a number of naval bases and built (1886–95) the Kiel Canal, which connected the Baltic and North Seas. The situation changed after Germany's defeat in World War I (which resulted, in particular, in the destruction of the main forces of the German navy and the limitation of Germany's naval armaments). After the seizure of power by the National Socialists (1933), German imperialism, with the complicity of the Western powers (the Anglo-German naval agreement of 1935 and others), sought to revive the navy on the B.M. The defeat of Nazi Germany in World War II, strengthening the position of the USSR on the B. m., the creation of the Polish People's Republic and the German Democratic Republic radically changed the balance of forces and the entire situation on the B. m. in favor of the socialist countries.

Economic and geographical outline.

The economic significance of the Baltic Sea is determined by its central position in relation to the economically developed states located on its shores - the USSR, Poland, the German Democratic Republic, the Federal Republic of Germany, Denmark, Sweden, and Finland. About 140 million people live in these countries (the USSR is considered as part of the regions of the RSFSR and the union republics of Estonia, Latvia, and Lithuania adjoining the Byelorussian m.). and produces about 15% of the world's industrial products. B. m. For the USSR serves as the shortest exit from the regions of the Center, West and North-West to the world sea routes of the Atlantic Ocean; large coastal shipments are carried out along the Baltic Sea, including shipments from the ports of the Black Sea; on the coast of the Baltic Sea are the bases of the Soviet expeditionary fishing fleet, which is fishing in the Atlantic Ocean. B passes through B. m. including foreign trade of Poland, East Germany, Sweden, Denmark and the vast majority of exports and imports of Finland. In the freight turnover of B. m., Petroleum products (from the ports of the USSR and from the Atlantic Ocean), coal (from Poland, the USSR), timber (from Finland, Sweden, and the USSR), cellulose and paper (from Sweden and Finland), and iron ore ( from Sweden); Machinery and equipment also play an important role in cargo turnover, the major producers and consumers of which are all countries located on the shores and in the basin of the Baltic Sea.The exit from the Baltic Sea to the Atlantic Ocean is through the Øresund Strait, which belongs to the territorial waters of Sweden and Denmark. , and through the Kiel Canal, which has international statute. Largest ports B. m .: Leningrad (FRG), NATO (in the western part of the B. m., In particular on the territory of the FRG and Denmark, NATO air and naval bases are located) and, on the other, - the desire of the progressive forces to transform the B. m. . to the peace zone.

M.N.Sokolov.

Literature:

Betin VV, Ice conditions in the Baltic Sea region and on the approaches to it and their long-term changes, “Tr. State Oceanographic Institute ", 1957, at. 41;
Hydrochemical regime of the Baltic Sea, L., 1965;
Egorieva A.V., Baltic Sea, M., 1961;
Zenkevich L. A., Biology of the seas of the USSR, M., 1963;
Soskin I.M., Long-term changes hydrological characteristics Baltic Sea, L., 1963.

This article or section uses the text of the Great Soviet Encyclopedia.

Links

Baltic Sea in the book: A. D. Dobrovolsky, B. S. Zalogin. Seas of the USSR. Publishing house Mosk. un-that, 1982.

Kaliningraders are lucky to live near Baltic Sea... After all, your sea is very cool! All the more so when it is so interesting and always different: harsh and merciless in the stormy season, quiet and welcoming on hot summer days. Also, depending on the weather, the Baltic waters often change their color. Now it is of warm blue shades, then suddenly it turns into greenish-gray colors, and in stormy weather the sea is completely bluish-black. Many of us are quite familiar with the contour of the Baltic Sea from maps, but few people think about how the Baltic Sea is arranged under the surface of the water, what kind of bottom relief does it have? The answer to this question can be found on the third floor. Marine Aquarium Gdynia (Polish. Akwarium Gdyńskie), where the unique layout of the Baltic Sea and the coast is located.

Located at the tip of Gdynia's South Pier, the Marine Aquarium, which opened in 1971, is one of the city's most significant landmarks. In addition to a voluminous map of the Baltic Sea and all kinds of marine exhibits, here you can observe the life of more than 1600 aquatic inhabitants from different parts of the world. A separate reportage will be devoted to them.

In the meantime, let's look at the model of the bottom relief of the Baltic Sea, on which all significant depths (depressions) are indicated, the largest (459 m) of which is called - Landsort(Polish. Głębię Landsort). The average sea depth is 52.3 m.

The Baltic Sea, sometimes called the Mediterranean Sea of the North, because of its location among the land, occupies a surface of 415 thousand square meters. km. Geographically, it is part of the Atlantic Ocean and is connected to the North Sea by the Danish Straits.

03. The Gulf of Bothnia and Finland.

04. St. Petersburg.

Along the northern coast of the Baltic Sea, in the Gulfs of Finland and Bothnia, there are many thousands of islands and rocks. This is a famous area of skerries, which in its length and originality is unmatched in any other part of the World Ocean.

06. Aland Islands.

07. The capital of Norway is Oslo.

Despite the fact that the Baltic Sea lies among the land, the ocean affects it noticeably. The coastal inhabitants of the Baltic experience the influence of the ocean on a daily basis. Deep cyclones from the Atlantic Ocean often visit the Baltic. When they pass, strong south-westerly winds blow, often turning into storms. The maximum summer temperature in the Baltic is only +18 +20 degrees, which makes it not the most popular sea for a beach holiday.

08. The closest to the Kaliningrad region, a large depression is located in the area of the Polish Gdansk - Głębię Gdańską(118 m). Three spits are also visible: Curonian, Vistula and Khel.

09. Gdynia.

10. Kaliningrad and the Curonian Spit.

11. The northern and eastern parts of the sea are "decorated" with powerful bays - Bothnian, Finnish and Riga.

12. Gulf of Finland and the capitals of Estonia and Finland.

13. The Baltic Sea is rich in amber. The world's largest amber deposit is located in our Kaliningrad region, near the village. Amber.

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Up-to-date in the course“Geography of Russia. Economy and geographic areas "

Section II - Regions of Russia. European part

Chapter - Northwest Region

Paragraph outline

1. Geographical location

2. Main characteristics (area, length of the coastline)

3. Geological history of the formation of the sea and toponymy of names

4. The nature of the Baltic Sea

depths and bottom of the sea

climate (winter and summer)

water properties - S% o, T mode

rivers flowing into the sea

5. History of development and conquest of territories (access to the Baltic)

6. Economic value.

mineral resources

biological resources

port cities

transport routes

recreational resources

7. Man-made loads on natural complex Baltic

Geographical position. Main characteristics.

The waters of the Baltic Sea wash over the northwestern shores of the European part of Russia. The Baltic Sea is internal, it is separated from the Atlantic Ocean by the Scandinavian Peninsula and washes the shores of the Leningrad and Kaliningrad regions of Russia. The sea is connected to the ocean by narrow and shallow straits, which makes water exchange difficult. Full renewal of water in the sea takes 20-40 years. The Baltic Sea has three large bays: the Bothnian, Finnish, Riga and Curonian Lagoon (freshwater, separated from the sea by the sandy Curonian Spit). Eastern The Gulf of Finland is called the Neva Bay. The area of the Baltic Sea is 419 thousand km2, it is almost equal to the area of the Black Sea (422 thousand km2). The length of the Baltic coastline is 7 thousand km. Russia has about 500 km of coastline, that is, about 7%.

The Gulf of Finland.

The Gulf of Finland is one of the largest bays in the Baltic Sea, washing the shores of Finland, Russia and Estonia. In the XVIII century it was referred to as the Kronstadt Gulf. The area of the bay is 29.5 thousand km2. The bay is shallow. The average depth is 38 m, the maximum depth - 121 m is located near the island. Prangli. About 29 rivers flow into the Gulf of Finland, the largest of which are the Neva and Narva. There are many islands throughout the bay, for example, Kotlin, Berezovye, Vysotsky, etc.

Toponymy of the names of the Baltic Sea

The name Balticum mare was first mentioned by the North German chronicler Adam of Bremen in 1075. The origin of the name has not been conclusively clarified. The most common are two versions. According to the first, the name is from (Lithuanian) baltas, (Latvian) balts "white", which may be associated with the color of the sandy shores of this sea. According to another version, the name is derived from (Latin) balteus "belt", and this is due to the fact that this sea continues the chain of seas that encircle mainland Europe. In medieval Russia, it was called the Varangian Sea (from the Varangians) or the Sveiskoe (Svebskoe, Svevskoe) Sea from the ethnonym Svei - "Swedes". On Russian maps of the 18th century. the form Baltic Sea was used, but the well-known and now the name of the Baltic Sea is fixed in use. The same name is used in other countries washed by this sea, although in Germany it is also the East Sea (Ostsee), and in Estonia the West Sea (Laa "nemeri).

Features of the nature of the Baltic Sea.

Baltic Sea in March 2000 (NASA)

The Baltic Sea is located within the continental shelf. The average sea depth is 51 meters. In the areas of shoals, banks, near the islands, there are shallow depths (up to 12 meters). There are several basins in which depths reach 200 meters. The greatest depth of the Baltic Sea is recorded in the Landsort Basin - 470 meters. On the climate The Baltic Sea is influenced by its location in the zone of temperate latitudes, the proximity of the Atlantic Ocean and the location of a large part of the sea inside the continent. The weather in the Baltic is largely due to the impact of the Icelandic minimum, the Siberian and Azov anticyclones. Seasonal characteristics differ depending on whose influence is dominant. In autumn and winter, the Baltic Sea is influenced by the Icelandic minimum and the Siberian maximum. As a result, the sea is at the mercy of cyclones, which spread from west to east in autumn and northeast in winter. This period is characterized by cloudy weather with large southwestern and westerly winds. Approximately 250 large and small rivers carry their waters to the Baltic Sea. During the year they give to the sea about 433 km3, which is 2.1% of the total volume of the sea. The most full-flowing rivers are: the Neva, which flows in 83.5 km3 per year, the Vistula (30.4 km3 per year), the Neman (20.8 km3 per year) and the Daugava (19.7 km3 per year). In winter, the waters of the Baltic Sea are covered with ice. But during the same winter, ice can melt several times and again fetter the waters. This sea is never completely covered with ice. Practically not observed in the Baltic Sea tides... The tides in the Baltic Sea are semi-diurnal and diurnal, but their magnitude does not exceed 20 centimeters. The currents affecting surface waters are influenced by winds and river flows. More important are surge phenomena- sea level fluctuations, which can reach 50 centimeters off the coast, and 2 meters at the tops of bays and bays. In the top of the Gulf of Finland, in some meteorological situations, level rises of up to 5 meters are possible. The annual amplitude of sea level fluctuations can reach 3.6 meters near Kronstadt.

Natural resources

Widely developed in the Baltic Sea fishing... Herring, sprat, cod, whitefish, lamprey, salmon and other types of fish are caught here. Also in these waters, a large amount of algae is mined. There are many marine farms in the Baltic Sea where the most sought-after fish species are raised. There are a large number of mineral deposits on the coast. Amber mining is being carried out in the Kaliningrad region. In the depths of the Baltic Sea there is oil... Discovered ferromanganese nodules... With the collapse of the USSR, Russia in the Baltic has not a window, but a window. The ports of vital importance for the country turned out to be outside Russia: in Estonia - Novotallinsky, in Latvia - Riga, Ventspils, in Lithuania - Klaipeda. St. Petersburg is the most major port in the Baltic. By the Volga-Baltic route, the sea connects with the Volga, through the White Sea-Baltic channel - with the White Sea.

Environmental protection

Eutrophication;
Oil pollution;
Biodiversity conservation;
High degree of toxic pollution.

The number one ecological problem of today's Baltic is excessive intake of nitrogen and phosphorus into the water area as a result of washout from fertilized fields, with municipal wastewaters of cities and waste from some enterprises. Because of these nutrients, the sea becomes "over-fertilized", organic matter is not completely processed and, when oxygen is deficient, begin to decompose, releasing hydrogen sulfide, which is harmful to marine life. The second most important problem of the Baltic Sea is accumulation of heavy metals - mercury, lead, copper, zinc, cadmium, cobalt, nickel... About half of the total mass of these metals enters the sea with atmospheric precipitation, the rest - during direct discharge into the water area or with river runoff of household and industrial waste. The presence of dumps of chemical weapons (the disposal of containers with toxic substances was carried out after the Second World War) greatly affects the ecology of the Baltic Sea. Oceanographers aboard the Professor Shtokman research vessel mapped the discovered ships with chemical weapons, examined them with the help of descent vehicles, took water and soil samples, and studied currents in the area of the sunken ships. As a result of this work, it was established that a leak of toxic substances has already begun from some ships. The 200-km coastal zone is polluted by NP. Concentration almost everywhere remains within 200 grams per square meter. Up to 600 thousand tons of oil gets into the water area annually with various effluents. Oil covers the surface of the water mirror with a film that does not allow oxygen to penetrate into the depths. Substances that are toxic to living organisms accumulate. All environmental problems of the Baltic Sea are determined by its pollution from many different sources through rivers, pipelines, landfills, from the operation of ships and, finally, from the air. To protect the sensitive marine environment of the Baltic, the countries adjacent to the Baltic Sea created and signed in 1974 the Helsinki Convention on the Environmental Protection of the Baltic Sea Area.

The Baltic Sea is connected to the North Sea by the Øresund straits (Sound), Big and Small Belts, Kattegat and Skagerrak. Washes the shores of Russia, Estonia, Latvia, Lithuania, Poland, Germany, Denmark, Sweden, Finland.

The maritime border of the Baltic Sea runs along the southern entrances of the Øresund straits, the large and small Belta. The area is 386 thousand km². The average depth is 71 m. The shores of the Baltic Sea in the south and southeast. mostly low-lying, sandy, lagoon type; from the land side - dunes covered with forest, from the sea side - sandy and pebble beaches. In the north, the shores are high, rocky, mostly skerry type. The coastline is heavily indented and forms numerous bays and bays.

Largest bays: Bothnian (according to physical and geographical conditions it is a sea), Finnish, Riga, Curonian, Gdansk Bay, Szczecin, etc.

Islands of the Baltic Sea of continental origin. There are many small rocky islets - skerries located along the northern shores and concentrated in the groups of the Vasi and Aland Islands. The largest islands are: Gotland, Bornholm, Sarema, Muhu, Hiuma, Oland, Rügen, etc. A large number of rivers flow into the Baltic Sea, the largest of which are the Neva, Western Dvina, Neman, Vistula, Odra, etc.

The Baltic Sea is a shallow shelf sea. Depths of 40-100 m prevail.The Kattegat straits are the shallowest areas. (average depth 28 m), Øresund, large and small Belty, eastern parts of the Gulf of Finland and Bothnia and the Gulf of Riga. These areas of the seabed have a leveled accumulative relief and a well-developed cover of loose sediments. Most of the bottom of the Baltic Sea is characterized by a highly dissected relief, there are relatively deep basins: the Gotland (249 m), Bornholm (96 m), in the Sodra-Kvarken Strait (244 m) and the deepest - Landsortsjupet south of Stockholm (459 m)... There are numerous stone ridges; in the central part of the sea, ledges are traced - continuation of the Cambrian-Ordovician (from the northern coast of Estonia to the northern tip of the island of Öland) and Silurian klint, underwater valleys, flooded by the sea, glacial-accumulative relief forms.

In the central part of the sea, the bottom is composed of Silurian and Devonian rocks, hidden to the south under a layer of glacial and marine sediments of considerable thickness.

The presence of underwater river valleys and the absence of marine sediments under the stratum of glacial deposits indicate that in the preglacial time there was land on the site of the Baltic Sea. During at least the last ice age, the Baltic Sea basin was completely covered with ice. Only about 13 thousand years ago there was a connection with the ocean, and sea waters filled the depression; the Yoldian Sea was formed (by Joldia clam)... The Yoldian Sea phase a little earlier (15 thousand years ago) preceded by the phase of the Baltic glacial lake, which had not yet communicated with the sea. About 9-7.5 thousand years ago, as a result of tectonic uplift in Central Sweden, the connection between the Yoldian Sea and the ocean ceased, and the Baltic Sea again became a lake. This phase of the development of the Baltic Sea is known as Lake Ancylovo (for the Ancylus clam)... A new sinking of land in the area of the modern Danish straits, which took place about 7-7.5 thousand years ago, and an extensive transgression led to the renewal of communication with the ocean and the formation of the Litorina Sea. The level of the last sea was several meters higher than the present one, and the salinity was higher. Deposits of the Littorina transgression are widely known on the present-day coast of the Baltic Sea. The age-old uplift in the northern part of the Baltic Sea basin continues to this day, reaching 1 m per hundred years in the north of the Gulf of Bothnia and gradually decreasing to the south.

The climate of the Baltic Sea is maritime temperate, strongly influenced by the Atlantic Ocean. It is characterized by relatively small annual temperature fluctuations, frequent precipitation, fairly evenly distributed throughout the year, and fogs during cold and transitional seasons. During the year, westerly winds prevail, which are associated with cyclones coming from the Atlantic Ocean. Cyclonic activity reaches its highest intensity in the autumn-winter months. At this time, cyclones are accompanied by strong winds, frequent storms and cause large rises in the water level off the coast. In the summer months, cyclones weaken and their frequency decreases. The invasion of anticyclones is accompanied by winds from the east.

The length of the Baltic Sea by 12 ° along the meridian determines the noticeable differences in the climatic conditions of its individual regions. Average air temperature in the southern part of the Baltic Sea: in January -1.1 ° C, in July 17.5 ° C; middle part: in January -2.3 ° C, July 16.5 ° C; Gulf of Finland: in January -5 ° C, in July 17 ° C; northern part of the Gulf of Bothnia: -10.3 ° C in January, 15.6 ° C in July. Cloudiness in summer is about 60%, in winter more than 80%. Average annual precipitation in the north is about 500 mm, in the south over 600 mm, and in some areas up to 1000 mm. The largest number of foggy days falls on the southern and middle part of the Baltic Sea, where it reaches 59 days a year on average, the smallest - in the north. Gulf of Bothnia (up to 22 days a year).

The hydrological conditions of the Baltic Sea are mainly determined by its climate, excess fresh water and water exchange with the North Sea. An excess of fresh water, equal to 472 km3 per year, is formed due to continental runoff. The amount of water entering the sediment (172.0 km³ per year), is equal to evaporation. Water exchange with the North Sea averages 1,659 km3 per year (salt water 1187 km³ per year, fresh water - 472 km³ per year)... Fresh water flows out of the Baltic Sea into the North Sea in a runoff current, while salty water flows through the straits from the North Sea to the Baltic Sea in a deep current. Strong westerly winds usually cause inflow, and easterly winds - drainage of water from the Baltic Sea through all sections of the Øresund straits, the Great and Little Belta.

The currents of the Baltic Sea form a counterclockwise vortex. Along the southern coast, the current is directed to the east, along the eastern - to the north, along the western - to the south, and along the northern coast - to the west. The speed of these currents ranges from 5 to 20 m / sec. Under the influence of winds, currents can change direction and their speed near the coast can reach 80 cm / sec and more, and in the open part - 30 cm / sec.

The surface water temperature in August is 15 ° C, 17 ° C in the Gulf of Finland; in the Gulf of Bothnia 9 ° C, 13 ° C and in the central part of the sea 14 ° C, 18 ° C, and in the south it reaches 20 ° C. In February - March, the temperature in the open sea is 1 ° С-3 ° С, in the Bothnian, Finnish, Riga and other bays and bays below 0 ° С. The salinity of surface water rapidly decreases with distance from the straits from 11 ‰ to 6-8 ‰ (1 ‰ -0.1%) in the central part of the sea. In the Gulf of Bothnia, it is 4-5 ‰ (on the north of the bay 2 ‰), in the Gulf of Finland 3-6 ‰ (at the top of the bay 2 ‰ or less)... In the deep and bottom layers of water, the temperature is 5 ° C or more, salinity varies from 16 ‰ in the west to 12-13 ‰ in the central part and 10 ‰ in the north of the sea. In the years when the inflow of water increases, salinity rises in the west to 20 З, in the central part of the sea to 14-15 ‰, and in the years when the inflow decreases, in the middle parts of the sea to 11 ‰.

Ice usually appears in early November to the north of the Gulf of Bothnia and reaches its greatest distribution in early March. At this time, a significant part of the Gulfs of Riga, Finland and Bothnia is covered with stationary ice. The central part of the sea is usually ice-free.

The amount of ice in the Baltic Sea varies from year to year. In extremely harsh winters, almost the entire sea is covered with ice, in mild winters only bays. The northern part of the Gulf of Bothnia is covered with ice 210 days a year, the middle part 185 days; Gulf of Riga - 80-90 days, Danish Straits - 16-45 days.

The Baltic Sea level is subject to fluctuations under the influence of changes in wind direction, atmospheric pressure (progressive-standing long waves, seiches), inflow of river waters and waters of the North Sea. The period of these changes varies from several hours to several days. Rapidly changing cyclones cause level fluctuations of up to 0.5 m or more near the coast open sea and up to 1.5-3 m at the tops of bays and bays. Especially large rises in water, which are, as a rule, a consequence of the imposition of a wind surge on the crest of a long wave, occur in the Neva Bay. The greatest rise in water in Leningrad was noted in November 1824 (about 410 cm) and in September 1924 (369 cm).

The level fluctuations associated with tides are extremely small. Hot flashes have an irregular semidiurnal, irregular daily and diurnal character. Their size varies from 4 cm (Klaipeda) up to 10 cm (The Gulf of Finland).

The fauna of the Baltic Sea is poor in species, but rich in quantity. The brackish-water race of the Atlantic herring lives in the Baltic Sea (herring), Baltic sprat, as well as cod, flounder, salmon, eel, smelt, vendace, whitefish, perch. Mammals include the Baltic seal. Intensive fishing is carried out in the Baltic Sea.

Russian hydrographic and cartographic work began in the Gulf of Finland at the beginning of the 18th century. In 1738, F.I.Soimonov published an atlas of the Baltic Sea, compiled from Russian and foreign sources. In the middle of the 18th century. many years of research in the Baltic Sea was carried out by A.I. Nagaev, who made a detailed pilot. First deep-sea hydrological research in the mid-1880s. were performed by S.O. Makarov. Since 1920, hydrological work has been carried out by the Hydrographic Department and the State Hydrological Institute, and after the Patriotic War of 1941–45, extensive comprehensive research was launched under the leadership of the Leningrad branch of the USSR State Oceanographic Institute.