The main feature that distinguishes the waters of the oceans from the waters of land is their high salinity.

The number of grams of substances dissolved in 1 liter of water is called salinity . Sea water is a solution of 44 chemical elements, but leading role salts, chlorides (89%) and sulfates (10%) play in it. Sea water is a relatively homogeneous solution of various salts, fully ionized, 99% of the total salts are sodium, magnesium, potassium, calcium, chlorine and sulfur ions. In addition, it also contains suspended particles, dissolved gases, some organic compounds. Table salt gives water a salty taste, while magnesium salt gives it a bitter taste.

Salinity is expressed in ppm (Latin pro mille - “per thousand”). This term means one thousandth of any value. Promille is denoted o / oo. The average salinity of sea water in the ocean is 35 o / oo, which means that 35 grams of a substance are dissolved in a liter of sea water. Salinity fluctuations depend on many factors:

from water evaporation. In this process, the salts do not evaporate;

From ice formation;

From precipitation;

From the runoff of river waters, especially for inland seas;

From melting ice.

Melting ice, precipitation, river water runoff - all this has a desalinating effect on sea water, and evaporation and ice formation, on the contrary, contribute to an increase in salinity. The main role in the change in salinity is played by evaporation and precipitation, therefore the salinity of surface waters is very dependent on climatic conditions associated with latitude (see "Water masses").

In the equatorial regions oceans salinity about 34 o/o, since here the surface is strongly heated from the Sun, ascending air currents are formed, a low pressure area is formed and an abundance of precipitation falls.

In tropical waters, where an area of ​​high pressure is formed, descending air flows do not contribute to precipitation and there are few rivers, salinity is 36 o/o.

In polar latitudes, where the melting ice has a strong desalination effect, the salinity is 32 o/o.

Rivers also have a desalination effect, so the salinity of ocean waters off the continents much less than in the center of the ocean, since the waters of the rivers desalinate the coastal waters.

The most salty is Red sea - 42 o/o, This is because this inland sea is spreading in tropical latitudes, where few rivers, drops out little rainfall, water evaporation from strong heating by the Sun is very large.

The salinity of another Inland Sea - the Baltic - is much lower - 11 o/o(in the center - 6 o / oo, in the eastern part of the Gulf of Finland up to 1 o / oo. This is due to the fact that this sea is located in a climatic zone where precipitation falls, and it falls into many rivers.

Sometimes the overall picture of the salinity of the oceans is disturbed currents , which is clearly seen in the example gulf stream- one of the most powerful currents in the ocean, whose branches can penetrate far into the Arctic Ocean. At the same time, the salinity of the current waters is much higher than the salinity of the ocean waters.

The reverse phenomenon is observed off the coast of North America, where the cold Labrador the current, moving from the polar latitudes, contributes to a decrease in salinity off the coast of the mainland.

The salinity of the deep layers of the World Ocean as a whole is practically constant. Waters whose salinity does not exceed 1 o / oo are called insipid .

Ocean water temperature

The ocean receives a lot of heat from the Sun - occupying a large area, it receives more heat than land. Water has high heat capacity, therefore, a huge amount of heat accumulates in the ocean. Only the top 10-meter layer of ocean water contains more heat than the entire atmosphere. But the sun's rays heat only the upper layer of water; heat is transferred down from this layer as a result of constant mixing water. But it should be noted that the water temperature decreases with depth, first abruptly, and then smoothly. At depth, the water is almost uniform in temperature, since the depth of the oceans is mainly filled with waters of the same origin, which form in the polar regions of the Earth. At a depth more than 3-4 thousand meters the temperature usually fluctuates from +2°С to 0°С.

The temperature of the oceans depends on latitude and distributed on its surface zonal. The highest average temperatures are located at the equator and are equal to 27°-28°C. Since our Earth is a sphere, with increasing latitude, the angle of incidence of the sun's beam decreases, the amount of solar radiation decreases, and the temperature of the waters of the World Ocean decreases. Due to the proximity of cold Antarctica, the rate of temperature decrease to the south is somewhat faster than to the north.

The temperature of sea water is affected by the climate of the surrounding areas: so, for example, the temperature of the waters of the Red Sea, surrounded by hot deserts, reaches 34 ° C.

The temperature of sea water in temperate latitudes is greatly influenced by season and even Times of Day.

The temperature of ocean waters is strongly influenced by ocean currents: warm currents carry water from the equator to temperate latitudes, and cold currents - from the polar regions. Such mixing of water contributes to a more uniform distribution of temperatures in the water masses.

For the entire ocean average temperature of the surface layer ocean waters is + 17.5 ° С. It decreases with depth, however, the temperature of the waters of hot springs at the bottom of the ocean reaches 400°C. The average temperature of the entire mass of ocean water is only 4°C. The highest average temperature at the surface of the water in the Pacific Ocean is 19°C, in the Indian - 17°C, in the Atlantic Ocean - 16°C, in the Arctic Ocean - 1°C.

So, the ocean absorbs heat 25-50% more than the land. The sun heats water all summer, and in winter this heat enters the atmosphere, so without the World Ocean, such severe frosts would come on Earth that all life on the planet would die. This is its huge role for the living beings of the Earth. It has been calculated that if the oceans did not keep warm so carefully, then the average temperature on our planet would be -21 ° C, which is 36 ° lower than what we have now.

Ice in the ocean

The freezing point of water with average salinity is 1.8°C below 0°. The higher the salinity of water, the lower its freezing point. The formation of ice in the ocean begins with the formation of fresh crystals, which then freeze. Between the crystals are droplets of salt water, which gradually drains, so young ice is more salty than old, desalinated ice. The thickness of first-year ice reaches 2-2.5 m, and multi-year ice have a thickness of up to 5 m.

Ice forms only in arctic and subarctic latitudes, where winters are long and very cold.

By origin, the ice found in the seas and oceans is not only marine, that is, formed when salt water freezes; fresh ice is carried by rivers and enters the ocean from continents and islands. continental ice in the ocean often form floating mountains - icebergs . These are giant ice mountains of various shapes. They broke away from the glaciers that cover the mainland. Northern icebergs separate from Greenland ice sheet , which annually releases more than 300 km 2 ice. In size, northern icebergs are inferior to southern icebergs, which are formed by breaking off ice blocks from covers of Antarctica . Most often, northern icebergs are 1-2 km long, but there are also those that reach 200 or even 300 km in length and more than 70 km in width. The height of individual ice mountains, together with the underwater part, can reach 600 m.

The sailing range of icebergs and the duration of their existence depend not only on the speed and direction of sea currents, but also on the properties of the iceberg itself. Very large and deeply frozen Antarctic icebergs exist for many years, and sometimes more than a decade. Greenland icebergs are melting faster, their lifespan is only 2-3 years. They are smaller and their freezing temperature is lower. Northern and southern icebergs differ from each other in their shape. Greenland icebergs are ice mountains of a domed shape, less often a pyramidal shape. Antarctic icebergs most often have a flat surface and vertical sheer walls.

Icebergs are carried away by sea currents to lower latitudes, where they gradually melt. For example, in the Atlantic Ocean, the remains of these ice mountains are sometimes found at the latitude of Bermuda and the Azores (30 ° -40 ° N). Sometimes icebergs end up in areas of intensive shipping, and they pose a threat here, because, firstly, the ice reflects sunlight, cools the air and contributes to the formation of fogs, and secondly, most of the iceberg is under water, and the collision of ships most often occurs with this part of the ice mountain. So, in 1912, the death of the steamer "Titanic" occurred as a result of its collision with an iceberg. To prevent this disaster, iceberg warning devices are now being installed on ships.

But icebergs can be source of fresh water , the lack of which is increasingly felt on the planet. Projects are already being developed to use icebergs for supply fresh water coastal regions of australia, South America, Asia, Africa. The initiator of the first conference to discuss the problem of "catching" and towing icebergs as a source of fresh water was Saudi Arabia- a state located in the desert.

In 1773, the first report appeared in the press about the so-called "black icebergs" found off the coast of Antarctica. New Zealand scientists have suggested that the black color of these ice mountains is caused by the activity of volcanoes in the South Shetland Islands. The glaciers on these islands are covered with a layer of volcanic dust that is not washed away by sea water.

Ice covers about 15% of the entire water area of ​​the World Ocean, that is, 55 million km2, including 38 million km2 in the Southern Hemisphere. The ice cover has a great influence on life in the ocean and on the Earth's climate.

02/10/2016 at 21:20 · pavlofox · 71 260

The most salty seas in the world

Around the world, there are about 80 seas that are an integral part of the oceans. All these waters are salty, but among them there are record holders, which are distinguished by a high concentration of salts and other minerals in their composition. The Baltic Sea is considered the freshest sea on the planet, the salinity of which is only 7 ‰ (ppm), which is equal to 7 grams per 1 liter of water. Among all the rest, we singled out the saltiest seas in the world.

10. White Sea | Salinity 30‰

They belong to the most salty seas in the world. Salinity here can reach 30‰ in some places. This is one of the smallest seas in Russia, with an area of ​​90,000 sq. km. The temperature here rises to 15 degrees in summer and drops to minus 1 degree in winter. The inhabitants of the White Sea are about 50 species of fish, including white whale, salmon, cod, smelt and others.

9. Chukchi Sea | Salinity 33‰

Included in the ten most salty in the world. Its salinity in winter is higher and can reach 33‰. It is located between Chukotka and Alaska on an area of ​​589,600 sq. km. The water temperature here is quite low: in summer - 12 degrees above zero, and in winter - minus 1.8 degrees. Walruses, seals, as well as fish - grayling, polar cod, Far Eastern navaga, arctic char and others live here.

8. Laptev Sea | Salinity 34‰

Covering an area of ​​662,000 sq. km., are among the most salty in the world. It is located between the New Siberian Islands and the Severnaya Zemlya Islands. The salinity of its waters reaches 34‰ in places, and the water temperature does not rise above 0 degrees all year round. Walrus, sterlet, sturgeon, perch and other animals live in the depths of the sea.

7. Barents Sea | Salinity 35‰

With a salinity of 35‰, it is one of the saltiest on earth and the most salty in Russia. It is washed by the waters of the White Sea and has an area of ​​1,424,000 sq. km. In winter, only the southwestern part of the sea does not freeze, the temperature here in summer does not exceed plus 12 degrees. The underwater world here is quite rich in fish, including capelin, perch, herring, catfish, killer whale, beluga and others.

6. Sea of ​​Japan | Salinity 35‰

Located between the shores of Eurasia, the Japanese Islands, as well as the island of Sakhalin, they are among the most salty in the world. Its salinity reaches 35‰. The annual temperature of the waters fluctuates between 0-+ 12 degrees in the north, and in the southern part 17-26 degrees above zero. The fauna here is very rich and includes many species of fish. Herring, pollock, saffron cod, flounder, pink salmon, chum salmon, anchovies, crabs, shrimps, oysters, squids and many others live here. Japanese salt waters occupy an area of ​​1,062,000 sq. km.

5. Ionian Sea | Salinity 38‰

considered the most dense and salty in Greece. It is perfect for those who do not know how to swim and want to learn. In summer, the temperature here fluctuates between 25-26 degrees above zero, and in winter it drops to plus 14 degrees. The salinity of the sea is about 38‰. The inhabitants of salt waters are fish such as tuna, flounder, mackerel and others. It occupies the Ionian Sea with an area of ​​169,000 sq. km.

4. Aegean Sea | Salinity 38.5‰

Aegean one of the ten most salty seas in the world. Its salinity is about 38.5‰. Due to the high salinity, after bathing in such water, it is recommended to wash with fresh water, since a high concentration of sodium can adversely affect the skin and mucous membranes. The winter temperature here is about 14 degrees above zero, and the summer is plus 24 degrees. It is inhabited by octopuses, sardines, sponges and other inhabitants. It is located between the peninsulas of the Balkans, Asia Minor and the island of Crete. The Aegean Sea has existed for about 20,000 years. It was formed as a result of the flooding of the Egenid land and occupied an area of ​​179,000 sq.m. Its appearance led to the formation of the islands of Crete, Lesbos, Euboea and others.

3. Mediterranean Sea | Salinity 39.5‰

Located between Europe and Africa. It is rightfully considered one of the most salty seas in the world, the salinity of which reaches 39.5 ‰ in places. It also belongs to the warmest seas of the World Ocean - the temperature here is plus 25 degrees in summer and minus 12 degrees in winter. It is inhabited by seals, sea turtles, as well as more than 500 species of fish, including sharks, rays, blennies, lobsters, crabs, mussels and many, many others.

2. Red Sea | Salinity 42‰

Located between Africa and Asia, one of the saltiest on planet Earth. Its salinity reaches 42 ‰, which is about 41 grams per liter of water. A very rich underwater world is concentrated here: sharks, dolphins, rays, moray eels and other living creatures are the inhabitants of the Red Sea. The water temperature is 25 degrees above zero all year round. In the Red Sea, the water is very well and evenly mixed. In winter, surface waters cool down, become denser and sink down, while warm waters from the depths rise up. In summer, water evaporates from the surface of the sea, and the remaining water becomes saltier, heavier and sinks. Less salty water rises in its place. Thus, the water in the sea is intensively mixed throughout the year, and throughout its volume the sea is the same in temperature and salinity, except in the depressions. In addition, the sea boasts amazing transparency.

1. Dead Sea | Salinity 270‰

- the saltiest in the world, which is located on the border of Israel and Jordan. The content of minerals is about 270 ‰, and the concentration of salts per 1 liter reaches 200 grams. The composition of the salts of the sea is significantly different from all others. It consists of 50% magnesium chloride, and is also rich in potassium, bromine, calcium and many other mineral elements. Potassium salts are artificially crystallized from its water. Water has the highest density here, which is 1.3-1.4 g / m³, which completely eliminates the possibility of drowning. In addition to unique salts, the sea contains therapeutic mud, which contains 45% salts. Its characteristics are a high pH value of 9, as well as a bitter and oily taste. The sea temperature can reach 40 degrees above zero, which creates intense evaporation and contributes to high density. If in other waters with high salinity diverse inhabitants live, then in the waters of the Dead Sea they cannot be found.

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3. Characteristics of the oceanic water environment.

© Vladimir Kalanov,
"Knowledge is power".

The oceanic environment, that is, sea water, is not just a substance known to us from birth, which is hydrogen oxide H 2 O. Sea water is a solution of a wide variety of substances. In the waters of the World Ocean are in the form of various compounds almost all known chemical elements.

Most of all, chlorides are dissolved in sea water (88.7%), among which sodium chloride, that is, common table salt NaCl, predominates. Significantly less sulfates, that is, salts of sulfuric acid, are found in sea water (10.8%). All other substances account for only 0.5% of the total salt composition of sea water.

After sodium salts, magnesium salts are in second place in sea water. This metal is used in the manufacture of light and strong alloys required in mechanical engineering, especially in aircraft construction. Each cubic meter of sea water contains 1.3 kilograms of magnesium. The technology of its extraction from sea water is based on the conversion of its soluble salts into insoluble compounds and their precipitation with lime. The cost of magnesium, obtained directly from sea water, turned out to be significantly lower than the cost of this metal, previously mined from ore materials, in particular, dolomites.

It is worth noting that bromine, discovered in 1826 by the French chemist A. Balard, is not contained in any mineral. You can get bromine only from sea water, where it is contained in a relatively small amount - 65 grams per cubic meter. Bromine is used in medicine as a sedative, as well as in photography and petrochemistry.

Already at the end of the 20th century, the ocean began to provide 90% of the world production of bromine and 60% of magnesium. Sodium and chlorine are extracted from sea water in significant quantities. As for edible (table) salt, a person has long received it from sea water by evaporation. Marine salt mines still operate in tropical countries, where salt is obtained directly from the shallow areas of the coast, fencing them off from the sea with dams. The technology here is not very sophisticated. The concentration of table salt in water is higher than the rest of the salts, and therefore, when evaporated, it is the first to precipitate. The crystals settled at the bottom are removed from the so-called mother liquor and washed with fresh water to remove the remains of magnesium salts, which give the salt a bitter taste.

A more advanced technology for extracting salt from sea water is used in numerous salt works in France and Spain, which supply large volumes of salt not only to the European market. For example, one of the new ways to produce salt is to install special seawater atomizers in the pools of salt works. Water turned into dust (suspension) has a huge evaporation area and from the smallest drops it evaporates instantly, and only salt falls on the ground.

The extraction of table salt from sea water will continue to increase, because deposits of rock salt, like other minerals, will sooner or later be depleted. Currently, about a quarter of all table salt necessary for mankind is mined in the sea, the rest is mined in salt mines.

Sea water also contains iodine. But the process of obtaining iodine directly from water would be completely unprofitable. Therefore, iodine is obtained from dried brown algae growing in the ocean.

Even gold is contained in ocean water, though in negligible amounts - 0.00001 grams per cubic meter. There is a well-known attempt by German chemists in the 1930s to extract gold from the waters of the German Sea (as the North Sea is often called in German). However, it was not possible to fill the vaults of the Reichsbank with gold bars: the production costs would have exceeded the value of the gold itself.

Some scientists suggest that in the next few decades it may become economically feasible to obtain heavy hydrogen (deuterium) from the sea, and then mankind will be provided with energy for millions of years to come... But uranium is already being mined from sea water on an industrial scale. Since 1986, the world's first plant for extracting uranium from sea water has been operating on the coast of the Inland Sea of ​​Japan. The complex and expensive technology is designed to produce 10 kg of metal per year. To obtain such an amount of uranium, more than 13 million tons of sea water must be filtered and subjected to ion treatment. But persistent in work, the Japanese cope with this work. In addition, they are well aware of what atomic energy is. -)

An indicator of the amount of chemicals dissolved in water is a special characteristic called salinity. Salinity is the mass of all salts, expressed in grams, contained in 1 kg of sea water.. Salinity is measured in thousandths, or ppm (‰). On the surface of the open ocean, salinity fluctuations are small: from 32 to 38‰. The average surface salinity of the World Ocean is about 35‰ (more precisely, 34.73‰).

The waters of the Atlantic and Pacific Oceans have salinity slightly above average (34.87‰), while the waters of the Indian Ocean are slightly lower (34.58‰). This is where the freshening effect of the Antarctic ice comes into play. For comparison, we point out that the usual salinity of river waters does not exceed 0.15‰, which is 230 times less than the surface salinity of sea water.

The least salty open ocean are the waters of the polar regions of both hemispheres. This is due to melting continental ice, especially in the Southern Hemisphere, and large volumes of river flows in the Northern Hemisphere.

Salinity increases towards the tropics. The highest concentration of salts is observed not at the equator, but in the latitude bands 3°-20° south and north of the equator. These bands are sometimes called salinity belts.

The fact that the surface water salinity is relatively low in the equatorial zone is explained by the fact that the equator is a zone of heavy tropical rains that desalinate the water. Often, around the equator, dense clouds cover the ocean from direct sunlight, which reduces the evaporation of water at such moments.

In marginal and especially inland seas, the salinity differs from that of the ocean. For example, in the Red Sea, the surface salinity of water reaches the highest values ​​in the World Ocean - up to 42‰. This is explained simply: the Red Sea is in a zone of high evaporation, and it communicates with the ocean through the shallow and narrow Bab el-Mandeb Strait, and does not receive fresh water from the continent, since not a single river flows into this sea, and rare rains unable to desalinate the water in any noticeable way.

The Baltic Sea, which extends far into the land, communicates with the ocean through several small and narrow straits, is located in a temperate zone and receives the waters of many large rivers and small rivers. Therefore, the Baltic is one of the most desalinated basins of the oceans. The surface salinity of the central part of the Baltic Sea is only 6-8 ‰, and in the north, in the shallow Gulf of Bothnia, it even drops to 2-3 ‰).

Salinity changes with depth. This is due to the movement of subsurface waters, that is, the hydrological regime of a particular basin. For example, in the equatorial latitudes of the Atlantic and Pacific oceans below a depth of 100-150 m, layers of very salty waters (above 36 ‰) are traced, which are formed due to the transfer of more salty tropical waters from the western margins of the oceans by deep countercurrents.

Salinity changes sharply only to depths of about 1500 m. Below this horizon, almost no fluctuations in salinity are observed. At great depths of different oceans, salinity indicators converge. Seasonal changes in salinity on the surface of the open ocean are insignificant, no more than 1 ‰.

An anomaly of salinity is considered by experts to be the salinity of water in the Red Sea at a depth of about 2000 m, which reaches 300 ‰.

The main method for determining the salinity of sea water is the titration method. The essence of the method is that a certain amount of silver nitrate (AgNO 3) is added to the water sample, which, in combination with sodium chloride of sea water, precipitates in the form of silver chloride. Since the ratio of the amount of sodium chloride to other substances dissolved in water is constant, then, by weighing the precipitated silver chloride, one can quite simply calculate the salinity of the water.

There are other ways to determine salinity. Since, for example, indicators such as the refraction of light in water, the density and electrical conductivity of water depend on its salinity, by determining them, it is possible to measure the salinity of water.

Taking samples of sea water to determine its salinity or other indicators is not an easy task. To do this, they use special samplers - bottles, which provide sampling from different depths or from different layers of water. This process requires a lot of attention and care from hydrologists.

So, the main processes that affect the salinity of water are the rate of water evaporation, the intensity of mixing of more saline waters with less saline ones, as well as the frequency and intensity of precipitation. These processes are determined by the climatic conditions of a particular region of the World Ocean.

In addition to these processes, the salinity of sea water is affected by the proximity of melting glaciers and the volume of fresh water brought by rivers.

In general, the percentage ratio of various salts in sea water in all areas of the ocean almost always remains the same. However, in some places, the chemical composition of sea water is significantly influenced by marine organisms. They use for their nutrition and development many substances dissolved in the sea, although in varying quantities. Some substances, such as phosphates and nitrogen compounds are consumed especially in large volumes. In areas where there are many marine organisms, the content of these substances in the water is somewhat reduced. The smallest organisms that make up plankton have a noticeable effect on the chemical processes occurring in sea water. They drift on the surface of the sea or in the near-surface layers of water and, dying, slowly and continuously fall to the bottom of the ocean.

Salinity of the oceans. Current monitoring map(increase) .

What is the total salt content in the oceans? Now it is not difficult to answer this question. If we proceed from the fact that the total amount of water in the oceans is 1370 million cubic kilometers, and the average concentration of salts in sea water is 35‰, that is, 35 g per liter, then it turns out that one cubic kilometer contains approximately 35 thousand tons salt. Then the amount of salt in the World Ocean will be expressed as an astronomical figure of 4.8 * 10 16 tons (that is, 48 ​​quadrillion tons).

This means that even the active extraction of salts for domestic and industrial needs will not be able to change the composition of sea water. In this respect, the ocean, without exaggeration, can be considered inexhaustible.

Now it is necessary to answer an equally important question: why is there so much salt in the ocean?

For many years science has been dominated by the hypothesis that salt was brought into the sea by rivers. But this hypothesis, at first glance quite convincing, turned out to be scientifically untenable. It has been established that every second the rivers of our planet carry about a million tons of water into the ocean, and their annual flow is 37 thousand cubic kilometers. It takes 37,000 years for the complete renewal of water in the World Ocean - approximately in such a time it is possible to fill the ocean with river runoff. And if we accept that in the geological history of the Earth there were at least one hundred thousand such periods, and the salt content in river water, on average, is about 1 gram per liter, then it turns out that for the entire geological history of the Earth, about 1 was carried into the ocean by rivers. 4*10 20 tons of salt. And according to the calculation of scientists, which we have just given, 4.8 * 10 16 tons of salt are dissolved in the World Ocean, that is, 3 thousand times less. But it's not only that. The chemical composition of salts dissolved in river water differs sharply from the composition sea ​​salt. If sodium and magnesium compounds with chlorine absolutely predominate in sea water (89% of the dry residue after evaporation of water and only 0.3% is calcium carbonate), then in river water calcium carbonate occupies the first place - over 60% of the dry residue, and sodium chlorides and magnesium together - only 5.2 percent.

Scientists have one assumption left: the ocean became salty in the process of its birth. The most ancient animals could not exist in slightly saline, and even more so in freshwater pools. This means that the composition of sea water has not changed since its inception. But what happened to the carbonates that came to the ocean along with river runoff over hundreds of millions of years? The only correct answer to this question was given by the founder of biogeochemistry, the great Russian scientist Academician V.I. Vernadsky. He argued that almost all calcium carbonate, as well as silicon salts, brought by rivers into the ocean, are immediately removed from the solution by those marine plants and animals that need these minerals for their skeletons, shells and shells. As these living organisms die off, the calcium carbonate (CaCO 3 ) contained in them and silicon salts are deposited on the seabed in the form of sediments of organic origin. So living organisms throughout the entire time of the existence of the World Ocean maintain the composition of its salts unchanged.

And now a few words about another mineral contained in sea water. We have spent so many words praising the ocean for the fact that its waters contain many different salts and other substances, including such as deuterium, uranium and even gold. But we did not mention the main and main mineral that is in the oceans - plain water. H 2 O. Without this “mineral”, there would be nothing on Earth at all: neither oceans, nor seas, nor us. About the main physical properties water we already had the opportunity to talk. Therefore, here we restrict ourselves to only a few remarks.

Throughout the history of science, people have not unraveled all the secrets of this rather simple chemical substance, the molecule of which consists of three atoms: two hydrogen atoms and one oxygen atom. By the way, modern science claims that hydrogen atoms make up 93% of all atoms in the universe.

And among the mysteries and mysteries of water, for example, such remain: why frozen water vapor turns into snowflakes, the shape of which is surprisingly correct geometric figure reminiscent of magnificent patterns. And the drawings on the window panes on frosty days? Instead of amorphous snow and ice, we see ice crystals lined up in such an amazing way that they look like leaves and branches of some fabulous trees.

Or here's another. Two gaseous substances - oxygen and hydrogen, combined together, turned into a liquid. Many other substances, including solids, when combined with hydrogen, become, like hydrogen, gaseous, for example, hydrogen sulfide H 2 S, hydrogen selenide (H 2 Se), or a compound with tellurium (H 2 Te).

It is known that water dissolves many substances well. It is said that it dissolves, albeit to a vanishingly small extent, even the glass of the glass into which we have poured it.

However, the most important thing to say about water is that water has become the cradle of life. Water, having initially dissolved dozens of chemical compounds in itself, that is, becoming sea water, turned into a solution unique in terms of the variety of components, which eventually turned out to be a favorable environment for the emergence and maintenance of organic life.

In the first chapter of this story of ours, we have already noted what is almost universally recognized. The hypothesis has now turned into a theory of the origin of life, each position of which, according to the authors of this theory, is based on the actual data of cosmogony, astronomy, historical geology, mineralogy, energy, physics, chemistry, including biological chemistry and other sciences.

The first opinion that life originated in the ocean was expressed in 1893 by the German naturalist G. Bunge. He realized that the amazing similarity between blood and sea water in terms of the composition of salts dissolved in them is not accidental. Later, the theory of the oceanic origin of the mineral composition of blood was developed in detail by the English physiologist McKellum, who confirmed the correctness of this assumption by the results of numerous blood tests of various animals, from invertebrate mollusks to mammals.

It turned out that not only blood, but the entire internal environment of our body shows traces that have been preserved from the long stay of our distant ancestors in sea water.

At present, world science has no doubts about the oceanic origin of life on Earth.

© Vladimir Kalanov,
"Knowledge is power"

Water is the simplest chemical compound of hydrogen and oxygen, but ocean water is a universal homogeneous ionized solution, which includes 75 chemical elements. These are solid mineral substances (salts), gases, as well as suspensions of organic and inorganic origin.

Vola has many different physical and chemical properties. First of all, they depend on the table of contents and ambient temperature. Let's give brief description some of them.

Water is a solvent. Since water is a solvent, it can be judged that all waters are gas-salt solutions of various chemical composition and various concentrations.

Salinity of ocean, sea and river water

Salinity of sea water(Table 1). The concentration of substances dissolved in water is characterized by salinity which is measured in ppm (% o), i.e., in grams of a substance per 1 kg of water.

Table 1. Salt content in sea and river water (in % of the total mass of salts)

Basic connections	Sea water	river water
Chlorides (NaCI, MgCb)
Sulphates (MgS0 4, CaS0 4, K 2 S0 4)
Carbonates (CaCOd)
Compounds of nitrogen, phosphorus, silicon, organic and other substances

Lines on a map connecting points of equal salinity are called isohalines.

Salinity of fresh water(see Table 1) is on average 0.146% o, and marine - on average 35 %O. Salts dissolved in water give it a bitter-salty taste.

About 27 out of 35 grams is sodium chloride (table salt), so the water is salty. Magnesium salts give it a bitter taste.

Since the water in the oceans was formed from hot saline solutions of the earth's interior and gases, its salinity was primordial. There is reason to believe that at the first stages of the formation of the ocean, its waters did not differ much from river waters in terms of salt composition. Differences were outlined and began to intensify after the transformation of rocks as a result of their weathering, as well as the development of the biosphere. The modern salt composition of the ocean, as fossil remains show, was formed no later than the Proterozoic.

In addition to chlorides, sulfites and carbonates, almost all chemical elements known on Earth, including noble metals, have been found in sea water. However, the content of most elements in seawater is negligible, for example, only 0.008 mg of gold in a cubic meter of water was detected, and the presence of tin and cobalt is indicated by their presence in the blood of marine animals and in bottom sediments.

Salinity of ocean waters- the value is not constant (Fig. 1). It depends on the climate (the ratio of precipitation and evaporation from the surface of the ocean), the formation or melting of ice, sea currents, near the continents - on the influx of fresh river water.

Rice. 1. Dependence of water salinity on latitude

In the open ocean, salinity ranges from 32-38%; in the outskirts and mediterranean seas its fluctuations are much greater.

The salinity of waters down to a depth of 200 m is especially strongly affected by the amount of precipitation and evaporation. Based on this, we can say that the salinity of sea water is subject to the law of zoning.

In the equatorial and subequatorial regions, salinity is 34% c, because the amount of precipitation is greater than the water spent on evaporation. In tropical and subtropical latitudes - 37, since there is little precipitation, and evaporation is high. In temperate latitudes - 35% o. The lowest salinity of sea water is observed in the subpolar and polar regions - only 32, since the amount of precipitation exceeds evaporation.

Sea currents, river runoff, and icebergs disrupt the zonal pattern of salinity. For example, in the temperate latitudes of the Northern Hemisphere, the salinity of water is greater near the western coasts of the continents, where more saline subtropical waters are brought with the help of currents, and the salinity of water is lower near the eastern coasts, where cold currents bring less saline water.

Seasonal changes in water salinity occur in subpolar latitudes: in autumn, due to the formation of ice and a decrease in the strength of river runoff, salinity increases, and in spring and summer, due to ice melting and increased river runoff, salinity decreases. Around Greenland and Antarctica, salinity decreases during the summer as a result of the melting of nearby icebergs and glaciers.

The most saline of all oceans is the Atlantic Ocean, the waters of the Arctic Ocean have the lowest salinity (especially off the Asian coast, near the mouths of Siberian rivers - less than 10% o).

Among the parts of the ocean - seas and bays - the maximum salinity is observed in areas limited by deserts, for example, in the Red Sea - 42% c, in the Persian Gulf - 39% c.

Its density, electrical conductivity, ice formation and many other properties depend on the salinity of water.

The gas composition of ocean water

In addition to various salts, various gases are dissolved in the waters of the World Ocean: nitrogen, oxygen, carbon dioxide, hydrogen sulfide, etc. As in the atmosphere, oxygen and nitrogen predominate in ocean waters, but in slightly different proportions (for example, the total amount of free oxygen in the ocean 7480 billion tons, which is 158 times less than in the atmosphere). Despite the fact that gases occupy a relatively small place in water, this is enough to influence organic life and various biological processes.

The amount of gases is determined by the temperature and salinity of water: the higher the temperature and salinity, the lower the solubility of gases and the lower their content in water.

So, for example, at 25 ° C, up to 4.9 cm / l of oxygen and 9.1 cm 3 / l of nitrogen can dissolve in water, at 5 ° C - 7.1 and 12.7 cm 3 / l, respectively. Two important consequences follow from this: 1) the oxygen content in the surface waters of the ocean is much higher in temperate and especially polar latitudes than in low latitudes (subtropical and tropical), which affects the development of organic life - the richness of the first and the relative poverty of the second waters; 2) in the same latitudes, the oxygen content in ocean waters is higher in winter than in summer.

Daily changes in the gas composition of water associated with temperature fluctuations are small.

The presence of oxygen in ocean water contributes to the development of organic life in it and the oxidation of organic and mineral products. The main source of oxygen in ocean water is phytoplankton, called the "lungs of the planet." Oxygen is mainly consumed for the respiration of plants and animals in the upper layers of sea waters and for the oxidation of various substances. In the depth interval of 600-2000 m, there is a layer oxygen minimum. A small amount of oxygen is combined with a high content of carbon dioxide. The reason is the decomposition in this water layer of the bulk of the organic matter coming from above and the intensive dissolution of biogenic carbonate. Both processes require free oxygen.

The amount of nitrogen in sea water is much less than in the atmosphere. This gas mainly enters the water from the air during the breakdown of organic matter, but is also produced during the respiration of marine organisms and their decomposition.

In the water column, in deep stagnant basins, as a result of the vital activity of organisms, hydrogen sulfide is formed, which is toxic and inhibits the biological productivity of water.

Heat capacity of ocean waters

Water is one of the most heat-intensive bodies in nature. The heat capacity of only a ten meter layer of the ocean is four times greater than the heat capacity of the entire atmosphere, and a 1 cm layer of water absorbs 94% of the solar heat entering its surface (Fig. 2). Due to this circumstance, the ocean slowly heats up and slowly releases heat. Due to the high heat capacity, all water bodies are powerful heat accumulators. Cooling, the water gradually releases its heat into the atmosphere. Therefore, the World Ocean performs the function thermostat our planet.

Rice. 2. Dependence of heat capacity of water on temperature

Ice and especially snow have the lowest thermal conductivity. As a result, ice protects the water on the surface of the reservoir from hypothermia, and snow protects the soil and winter crops from freezing.

Heat of evaporation water - 597 cal / g, and melting heat - 79.4 cal / g - these properties are very important for living organisms.

Ocean water temperature

An indicator of the thermal state of the ocean is temperature.

Average temperature of ocean waters- 4 °C.

Despite the fact that the surface layer of the ocean acts as the Earth's temperature regulator, in turn, the temperature of sea waters depends on heat balance(incoming and outgoing heat). The heat input is made up of , and the flow rate is made up of the costs of water evaporation and turbulent heat exchange with the atmosphere. Despite the fact that the proportion of heat spent on turbulent heat transfer is not large, its significance is enormous. It is with its help that the planetary redistribution of heat occurs through the atmosphere.

On the surface, the temperature of ocean waters ranges from -2 ° C (freezing temperature) to 29 ° C in the open ocean (35.6 ° C in the Persian Gulf). The average annual temperature of the surface waters of the World Ocean is 17.4°C, and in the Northern Hemisphere it is about 3°C ​​higher than in the Southern Hemisphere. The highest temperature of surface ocean waters in the Northern Hemisphere is in August, and the lowest is in February. In the Southern Hemisphere, the opposite is true.

Since it has thermal relationships with the atmosphere, the temperature of surface waters, like air temperature, depends on the latitude of the area, i.e., it is subject to the zonality law (Table 2). Zoning is expressed in a gradual decrease in water temperature from the equator to the poles.

In tropical and temperate latitudes, water temperature mainly depends on sea currents. So, due to warm currents in tropical latitudes in the west of the oceans, temperatures are 5-7 ° C higher than in the east. However, in the Northern Hemisphere, due to warm currents in the east of the oceans, temperatures are positive all year round, and in the west, due to cold currents, the water freezes in winter. In high latitudes, the temperature during the polar day is about 0 °C, and during the polar night under the ice it is about -1.5 (-1.7) °C. Here, the water temperature is mainly affected by ice phenomena. In autumn, heat is released, softening the temperature of air and water, and in spring, heat is spent on melting.

Table 2. Average annual temperatures of the surface waters of the oceans

	Average annual temperature, "C			Average annual temperature, °С
	North hemisphere	Southern Hemisphere		North hemisphere	Southern Hemisphere

The coldest of all oceans- Arctic, and the warmest- The Pacific Ocean, since its main area is located in the equatorial-tropical latitudes (the average annual temperature of the water surface is -19.1 ° C).

An important influence on the temperature of ocean water is exerted by the climate of the surrounding territories, as well as the time of year, since the sun's heat, which heats the upper layer of the World Ocean, depends on it. The highest water temperature in the Northern Hemisphere is observed in August, the lowest - in February, and in the Southern - vice versa. Daily fluctuations in sea water temperature at all latitudes are about 1 °C, the largest values ​​of annual temperature fluctuations are observed in subtropical latitudes - 8-10 °C.

The temperature of ocean water also changes with depth. It decreases and already at a depth of 1000 m almost everywhere (on average) below 5.0 °C. At a depth of 2000 m, the water temperature levels off, dropping to 2.0-3.0 ° C, and in polar latitudes - up to tenths of a degree above zero, after which it either drops very slowly or even rises slightly. For example, in the rift zones of the ocean, where at great depths there are powerful outlets of underground hot water under high pressure, with temperatures up to 250-300 °C. In general, two main layers of water are distinguished vertically in the World Ocean: warm superficial and powerful cold extending to the bottom. Between them is a transitional temperature jump layer, or main thermal clip, a sharp decrease in temperature occurs within it.

This picture of the vertical distribution of water temperature in the ocean is disturbed at high latitudes, where at a depth of 300–800 m there is a layer of warmer and saltier water that came from temperate latitudes (Table 3).

Table 3. Average values ​​of ocean water temperature, °С

	Depth, m
equatorial
tropical
Polar

Change in the volume of water with a change in temperature

A sudden increase in the volume of water when freezing is a peculiar property of water. With a sharp decrease in temperature and its transition through the zero mark, a sharp increase in the volume of ice occurs. As the volume increases, the ice becomes lighter and floats to the surface, becoming less dense. Ice protects the deep layers of water from freezing, as it is a poor conductor of heat. The volume of ice increases by more than 10% compared to the initial volume of water. When heated, a process occurs that is the opposite of expansion - compression.

Density of water

Temperature and salinity are the main factors that determine the density of water.

For sea water, the lower the temperature and the higher the salinity, the greater the density of the water (Fig. 3). So, at a salinity of 35% o and a temperature of 0 ° C, the density of sea water is 1.02813 g / cm 3 (the mass of each cubic meter of such sea water is 28.13 kg more than the corresponding volume of distilled water). The temperature of sea water of the highest density is not +4 °C, as in fresh water, but negative (-2.47 °C at a salinity of 30% c and -3.52 °C at a salinity of 35%o

Rice. 3. Relationship between the density of sea water and its salinity and temperature

Due to an increase in salinity, the density of water increases from the equator to the tropics, and as a result of a decrease in temperature, from temperate latitudes to the Arctic Circles. In winter, the polar waters sink and move in the bottom layers towards the equator, so the deep waters of the World Ocean are generally cold, but enriched with oxygen.

The dependence of water density on pressure was also revealed (Fig. 4).

Rice. 4. Dependence of the density of the sea water (A "= 35% o) on pressure at various temperatures

The ability of water to self-purify

This is an important property of water. In the process of evaporation, water passes through the soil, which, in turn, is a natural filter. However, if the pollution limit is violated, the self-cleaning process is violated.

Color and transparency depend on the reflection, absorption and scattering of sunlight, as well as on the presence of suspended particles of organic and mineral origin. In the open part, the color of the ocean is blue, near the coast, where there are a lot of suspensions, it is greenish, yellow, brown.

In the open part of the ocean, water transparency is higher than near the coast. In the Sargasso Sea, the water transparency is up to 67 m. During the development of plankton, the transparency decreases.

In the seas, such a phenomenon as glow of the sea (bioluminescence). Glow in sea water living organisms containing phosphorus, primarily such as protozoa (night light, etc.), bacteria, jellyfish, worms, fish. Presumably, the glow serves to scare away predators, to search for food, or to attract individuals of the opposite sex in the dark. The glow helps fishing boats find schools of fish in sea water.

Sound conductivity - acoustic property of water. Found in the oceans sound-diffusing mine and underwater "sound channel", possessing sonic superconductivity. The sound-diffusing layer rises at night and falls during the day. It is used by submariners to dampen submarine engine noise, and by fishing boats to detect schools of fish. "Sound
signal" is used for short-term forecasting of tsunami waves, in underwater navigation for ultra-long-range transmission of acoustic signals.

Electrical conductivity sea ​​water is high, it is directly proportional to salinity and temperature.

natural radioactivity sea ​​water is small. But many animals and plants have the ability to concentrate radioactive isotopes, so the seafood catch is tested for radioactivity.

Mobility is a characteristic property of liquid water. Under the influence of gravity, under the influence of wind, attraction by the Moon and the Sun and other factors, water moves. When moving, the water is mixed, which allows even distribution of waters of different salinity, chemical composition and temperature.

The surface of the oceans and seas covers about 70% of the surface of our planet. This is a whole world about which we know even less than about the world called land. We will touch on it with only a few words, because, having said the word "water", it is simply impossible not to say the word "sea".

Sea water is very complex in composition and contains almost all the elements of D.I. Mendeleev. For example, there are about three billion tons of gold alone in it, that is, as much by weight as all the fish in the seas and oceans. However, it is a very stable environment. In the open parts of the Ocean, sea water contains on average 35 g / kg of salts, in the Mediterranean - 38 g / kg, in the Baltic - 7 g / kg, in the Dead Sea - 278 g / kg. Salts in sea water are mainly in the form of compounds, the main of which are chlorides (88% by weight of all dissolved solids), followed by sulfates (10.8%) and carbonates (0.3%), the rest (0. 2%) includes compounds of silicon, nitrogen, phosphorus, organic substances.

The salty taste of water depends on the content of sodium chloride in it, otherwise table salt, the bitter taste is formed by magnesium chloride, sodium and magnesium sulfates. The slightly alkaline reaction of sea water, whose pH is 8.38-8.40, depends on the predominant amount of alkaline elements: sodium, calcium, magnesium, potassium.

In its composition, sea water is very similar to the salt composition of human blood. During the Great Patriotic War when there was a shortage of donor blood, Soviet doctors administered sea water intravenously as a blood substitute.

The ocean is the accumulator of life on our planet. The main feature of the ocean, if we consider it as a living space, is that the water column is inhabited in all three dimensions from the surface to the bottom sediments. The basis of life in the ocean is plankton.

R The distribution of salinity in the oceans depends mainly on climatic conditions, although salinity is partly influenced by several other factors, especially the nature and direction of currents. Outside the direct influence of land, the salinity of surface waters in the oceans ranges from 32 to 37.9 ppm.

The distribution of salinity over the surface of the ocean outside the direct influence of runoff from land is determined primarily by the balance of fresh water inflow and outflow. If the inflow of fresh water (precipitation + condensation) is greater than its outflow (evaporation), i.e., the inflow-output balance of fresh water is positive, the salinity of surface waters will be below normal (35 ppm). If the inflow of fresh water is less than the flow, i.e., the income-expenditure balance is negative, the salinity will be higher than 35 ppm.

A decrease in salinity is observed near the equator, in a calm zone. The salinity here is 34-35 ppm, since here a large amount of precipitation exceeds evaporation.

To the north and south of here, salinity first rises. The region of greatest salinity is found in the trade winds (between approximately 20 and 30° north and south latitude). We see on the map that these bands are especially pronounced in the Pacific Ocean. In the Atlantic Ocean, salinity is generally greater than in other oceans, and the maxima are located just at the tropics of Cancer and Capricorn. In the Indian Ocean, the maximum is at about 35°S. sh.

To the north and south of its maximum, salinity decreases, and in the middle latitudes of the temperate zone it is below normal; it is even less in the Arctic Ocean. The same decrease in salinity is seen in the southern circumpolar basin; there it reaches 32 ppm and even lower.

This uneven distribution of salinity depends on the distribution of barometric pressure, winds and precipitation. In the equatorial zone, the winds are not strong, evaporation is not great (although it is hot, the sky is covered with clouds); the air is humid, contains a lot of vapor, and there is a lot of precipitation. Due to the relatively small evaporation and dilution of salt water with precipitation, salinity becomes somewhat lower than normal. To the north and south of the equator, up to 30 ° N. sh. and yu. sh., - an area of ​​\u200b\u200bhigh barometric pressure, the air pulls towards the equator: the trade winds blow (constant northeast and southeast winds).

The descending currents of air, characteristic of areas of high pressure, descending to the surface of the ocean, heat up and move away from the state of saturation; cloudiness is small, there is little precipitation, fresh winds contribute to evaporation. Due to the large evaporation, the balance of fresh water inflow and outflow is negative, salinity is higher than normal.

Farther to the north and south, rather strong winds blow, mainly from the southwest and northwest. The humidity here is much higher, the sky is covered with clouds, there is a lot of precipitation, the balance of fresh water inflow and outflow is positive, the salinity is less than 35 ppm. In the circumpolar regions, the melting of the ice that is carried out also increases the supply of fresh water.

The decrease in salinity in the polar countries is explained by the low temperature in these areas, insignificant evaporation, and large clouds. In addition, vast expanses of land with large full-flowing rivers adjoin the northern polar seas; a large influx of fresh water greatly reduces salinity.

.The concept of water balance. World water balance.

Quantitatively, the water cycle is characterized by water balance. All components of the balance water can be divided into two parts: incoming and outgoing. In general, for the globe, the incoming part of the water balance is only atmospheric precipitation. The influx of water vapor from the deep layers of the earth and their condensation play an insignificant role. The expenditure part for the globe as a whole consists only of evaporation.

Every year, 577 thousand km3 of water evaporates from the surface of the globe.

During the year, only 0.037% of the total mass of the hydrosphere takes part in the World moisture cycle. Since the rate of transfer of individual types of water is not the same, the time of their consumption and renewal is also different (Table 2). The most rapidly renewed biological waters that are part of plants and living organisms. The change of atmospheric moisture and water reserves in the riverbeds is carried out in a few days. Water reserves in lakes are renewed within 17 years, in large lakes this process can last several hundred years. Thus, in Lake Baikal, the complete renewal of water reserves occurs within 380 years. The longest recovery period has water reserves in underground ice permafrost zones - 10,000 years. Complete renewal of ocean waters occurs after 2500 years. However, due to internal water exchange (sea currents), the waters of the World Ocean, on average, make a complete revolution within 63 years.

5. Thermal and ice regime of oceans and seas.

Self high temp. on the surface of the Red Sea + 32C. On the surface.

In black.m (in summer - + 26С, in winter - ice forms)

In the Azov m. (in summer - + 24С, in winter - 0С)

In the Baltic.m. (in summer - + 17С)

In the Baltic Sea (+10-+12C in summer, freezes in winter)

In Bel.m. (in summer - + 14C, in winter it freezes)

The temperature of the layers can be affected by the internal temperature of the earth (+72C)

The main source of heat received by the Mir.ok. surface is total solar radiation. Its share in the equatorial-tropical latitudes is 90%. The main expense item is the heat consumption for evaporation, which reaches 80% in the same latitudes. ADDITIONAL SOURCE of redistribution of heat - river waters, continents, prevailing winds, sea ​​currents.

Water is the most heat-intensive body, and World.ok. makes up 71% of the surface of the globe, acts as a battery and acts as a temperature regulator of the planet. Average water surface temperature = +17.4 3 more than average annual air temperature.

Due to the low thermal conductivity of water, heat is poorly transferred to depth. Therefore, in general, the world. OK. is a cold sphere and has a medium temp. about +4.

In the distribution of the temperature of the surface waters of the Ocean, zoning is observed (it decreases from the equator to the pole).

In tropical and especially temperate latitudes, the zonal pattern of water temperature is disturbed by currents, which leads to regionality (provinciality)

In tropical zones in the west of the oceans, water is 5-7C due to warm currents warmer than in the east, where there are cold currents.

In the temperate latitudes of the southern hemisphere, where the sea expanses dominate, the water temperature gradually decreases towards the poles. In the northern hemisphere, this pattern is violated by currents.

In all oceans, except for high latitudes, 2 main layers are distinguished vertically: warm surface and powerful cold, extending to the bottom. Between them lies the transition layer of the temperature jump, or the main thermocline, within which the temp. It drops sharply by 10-12C. The equalization of temperatures in the surface layer is facilitated by convection due to seasonal changes in the temperature of the active surface and salinity, as well as waves and currents.

In polar and subpolar latitudes, the distribution of temp. The vertical is different: on top is a thin cold desalinated layer, formed due to the melting of continental and river ice. Further, the temperature rises by 2C as a result of the influx of cold and dense tributaries.

Brackish water, like fresh water, freezes when it reaches its freezing point, and salty water freezes at its highest density temperature.

Freezing of the polar seas is prevented by wind waves, and rivers and rains contribute to reducing the salinity of the water, as well as snow and icebergs, which not only desalinate the water, but also lower its rate. And relieve anxiety.

SEA WATER BEGINS TO FREEZE at -2C.

ICE IN THE OCEAN are seasonal and exist for more than one year. The process of ice formation goes through several stages.

The initial form is (needle-crystals), after the spot-discs (ice fat), slush (a mushy mass of snow soaked in water) and sludge (accumulation of ice in the form of stripes) simultaneously appear. At the same time, ice banks (bands of ice frozen to land) form off the coast in shallow waters .. after that they turn into fast ice, with a further decrease in temp. Ice disks (pancake ice) are formed. In calm weather, a continuous thin ice crust is formed (in desalinated water - a bottle, and in salty - nalasom). Young ice up to 10 cm thick is called young ice. As it thickens, it becomes adult ice.

In the Arctic and Antarctica, in addition to seasonal ice, there are annual ice (up to 1 m thick), biennial (up to 2 m thick), and perennial ice (a polar pack that has existed for more than 2 years, 5-7 m thick, blue).

Ice classification.

By origin, ice in the OCEAN is divided into sea (slightly saline, occupy the bulk of the ice area in the world app.), River (distributed only in the northern hemisphere.) And mainland (also fresh).

By mobility, ice in the seas is divided into fixed (the main form is fast ice, several tens and even hundreds of kilometers wide. Such ice also includes stamukha ice that has come to the bottom in shallow waters) and drifting (moving under the influence of wind and current. icebergs or ice mountains, ice islands).

The destruction of ice occurs under the influence of solar radiation and warm air masses.

6. Dynamics of the waters of the World Ocean. Waves. Ocean water levels. Ebb and flow. Seaquakes and tsunamis.

Dynamics of the waters of the World Ocean

The waters of the oceans are never at rest. Movements occur not only in the surface water masses, but also in the depths, down to the bottom layers. Water particles perform both oscillatory and translational movements, usually combined, but with a noticeable predominance of one of them.

Wave movements (or excitement) - predominantly oscillatory movements. They represent oscillations of the water surface up and down from the average level; in the horizontal direction, the water masses do not move during waves. This can be seen by observing the float swaying on the waves.

Waves are characterized by the following elements:

The bottom of the wave is its lowest part;

The crest of a wave is its highest part;

The steepness of the slope of the wave - the angle between its slope and the horizontal surface;

Wave height - the vertical distance between the bottom and the crest. It can reach 14-25 meters;

Wavelength is the distance between two soles or two crests. The greatest length reaches 250 m, but waves up to 500 m are rare;

The speed of a wave is the distance traveled by the crest in one second. Wave speed characterizes the speed of its advancement.

Distinguished by origin the following types waves: friction waves (wind and deep), anemobaric, seismic, seiches, tidal waves.

The main reason for the formation of waves is the wind. At low speeds, ripples appear - a system of small uniform waves. They appear with every gust of wind and fade instantly. The crests of the wind waves are thrown back in the direction where the wind blows; when the wind subsides, the surface of the water continues to oscillate due to inertia - this is a swell. A large swell with a small steepness and a wavelength of up to 400 m in the absence of wind is called a wind swell. With a very strong wind turning into a storm, the leeward slope turns out to be steeper than the windward one, and with a very strong wind, the ridges break down and form white foam - “lambs”.

The excitement caused by the wind fades with depth. Deeper than 200 m, even strong excitement is imperceptible. When approaching a gently sloping coast, the lower part of the oncoming wave slows down on the ground; length decreases and height increases. The upper part of the wave moves faster than the lower part, the wave overturns, and its crest, falling, crumbles into small, air-saturated, foamy splashes. Waves breaking near the shore form surf. It is always parallel to the shore. The water splashed by the wave on the shore slowly flows back. When approaching a steep shore, the wave hits the rocks with all its might. The impact force sometimes reaches 30 tons per 1 m2. In this case, the main role is played not by the mechanical impacts of water masses on the rocks, but by the resulting water bubbles. They also destroy the rocks that make up the rocks (see "Coastal zone"). Breakwaters are built to protect port facilities, offshore berths, shores of stone or concrete blocks from waves.

The shape of the wave changes all the time, giving the impression of running. This is due to the fact that each water particle uniform movement describes circles around the level of equilibrium. All these particles move in the same direction. At any moment the particles are in different points circle, this is the system of waves.

The largest wind waves are observed in the Southern Hemisphere, since most of it is occupied by the ocean and westerly winds are the most constant and strong. Here the waves can reach 25 meters in height and 400 meters in length. Their speed of movement is about 20 m / s. In the seas, the waves are smaller: for example, in the large Mediterranean Sea, they reach only 5 m.

The 9-point Beaufort scale is used to assess the degree of sea roughness.

As a result of underwater earthquakes and volcanoes, seismic waves arise - tsunamis (Japanese). These are gigantic waves with destructive power. Underwater earthquakes or volcanic eruptions are usually accompanied by a strong earthquake, waterborne to the surface, which is unsafe for ships in the area. The subsequent waves caused by the impact are almost impossible to notice in the open sea, since they are gentle here. Approaching the shore, they become steeper and higher, acquiring terrible destructive power. As a result, giant waves can crash on the coast; their height is up to 50 m and more, and the propagation speed is from 50 to 1000 km/h.

Most often, tsunamis hit the Pacific coast, which is associated with high seismic activity in this area. Over the past millennium, the Pacific coast has been hit by tsunamis about 1000 times, while in other oceans (except the Arctic) these giant waves have occurred only dozens of times.

Usually, before the arrival of a tsunami, within a few minutes, the water recedes from the coast by several meters, and sometimes by kilometers; the further the water recedes, the greater the height of the tsunami should be expected. There is a special warning service that warns residents of the coast in advance of possible danger. Thanks to her, the number of victims is decreasing.

The damage caused by a tsunami is many times greater than the consequences caused by the earthquake itself or a volcanic eruption. Great damage was caused by the Kuril tsunami (1952), Chile (1960), Alaska (1964).

Tsunamis can spread over very long distances. For example, the shores of Japan were significantly damaged by the waves that arose during the earthquake in Chile, and the tsunami caused by the eruption of the Krakatoa volcano in Indonesia (1912) bypassed the entire World Ocean and was recorded in Le Havre (France) 32 hours 35 minutes after the last explosion , covering a distance equal to half the circumference of the globe. The damage caused by this giant wave is even difficult to assess: the shores of all nearby islands were flooded, not only the inhabitants, but also all the soil, were washed away from them, in the port of about. Java capital ships broke off the anchors, and they were thrown 9 meters high, 3 km inland; buildings were actually wiped off the face of the Earth.

The tsunami is associated not only with severe destruction, but also with significant loss of life. The tsunami caused by the eruption of the Krakatau volcano in 1883 claimed the lives of 40,000 people, and during the tsunami in 1703 in Japan, about 100,000 people died.

Under the influence of the force of attraction of the Moon and the Sun, periodic fluctuations in the level of the ocean occur - tidal movements of ocean waters. These movements occur approximately twice a day. At high tide, the ocean level gradually rises and reaches its highest position. At low tide, the level gradually drops to the lowest. At high tide, water flows towards the shores; at low tide, it flows away from the shores. Ebb and flow are standing waves.

According to the laws of interaction of cosmic bodies, the Earth and the Moon attract each other. This attraction contributes to the “bending” of the surface of the oceans towards the lunar attraction. The moon moves around the Earth, and a tidal wave “runs” across the ocean behind it, it will reach the shore - the tide. A little time will pass, the water, following the Moon, will move away from the shore - ebb. According to the same cosmic laws, ebbs and flows are also formed from the attraction of the Sun. It pulls the Earth much stronger than the Moon, but the Moon is much closer to the Earth, so the lunar tides are twice as strong as the sun's. If there were no Moon, then the tides on Earth would be 2.17 times less. The explanation of tide-forming forces was first given by I. Newton.

Highest level water at high tide is called high tide, lowest level at low tide - low water. The most common are semidiurnal tides, in which there are 2 full and 2 low waters per lunar day (24 hours 50 minutes). Depending on the position of the Moon relative to the Earth and on the configuration of the coastline, there are deviations from this regular alternation. Sometimes there is 1 full and 1 low water per day. Such a phenomenon can be observed on island arcs and coasts of East Asia and Central America.

The height of the tides is varied. Theoretically, one high water at lunar tide is 0.53 m and 0.24 m at solar tide. Thus, the highest tide should have a height of 0.77 m. In the open ocean and near the islands, the tide is close to theoretical: in the Hawaiian Islands - 1 m; on the Fiji Islands - 1.7 m, on the island of St. Helena - 1.1 m. At the mainlands, at the entrance to narrowing bays, the tide is much larger: in the Mezen Bay of the White Sea - 10 m; in Bristol Bay in England - 12m.

The largest recorded in the oceans are the following tides:

in the Atlantic Ocean in the Bay of Fundy - 16-17 m. This is the largest tide on the entire globe.

in the Sea of ​​Okhotsk in the Penzhina Bay - 12-14 m. This is the largest tide off the coast of Russia.

The significance of the tides is enormous: each tidal wave carries huge stock energy, and tidal power plants are now being built in a number of countries. In addition, the importance of the tides is great for maritime navigation.

The forward movement of water masses in the oceans and seas, caused by various forces, is called sea or ocean currents. These are "rivers in the ocean". They move at speeds up to 9 km / h. The causes that cause currents are the heating and cooling of the water surface, precipitation and evaporation, differences in water density, but the most significant cause of ocean currents is the wind.

Currents in the direction prevailing in them are divided into zonal (currents of westerly winds), going to the west, to the east, and meridional - carrying their waters to the north or south (Gulf Stream). In separate groups, countercurrents and monsoon currents can be distinguished. Countercurrents are currents that go towards neighboring, more powerful and extended ones. Currents that change their strength from season to season depending on the direction of coastal winds are called monsoons.

The most powerful in the oceans is the current of the Western winds. It is located in the Southern Hemisphere at latitudes off the coast of Antarctica, where there are no significant land masses. Strong and stable westerly winds prevail over this space, contributing to the intensive transfer of ocean water in an easterly direction. The course of the Western winds connects the waters of the three oceans in its circular flow and carries up to 200 million tons of water every second. The width of the current of the Western winds is 1300 km, but its speed is low: to bypass Antarctica once, the waters of the current need 16 years.

Another powerful current is the Gulf Stream. It carries 75 million tons every second, which is 3 times less than the current of the Western winds. The role of the Gulf Stream is very large: it carries tropical waters Atlantic Ocean to temperate latitudes, due to which the climate of Europe is mild and warm. Approaching Europe, the Gulf Stream is no longer the same stream that breaks out of the Gulf of Mexico, so the northern continuation of this current is called the North Atlantic Current.

Ocean currents differ not only in directions, but also, depending on temperature, are divided into warm, cold and neutral. Currents moving away from the equator are warm, while those moving towards the equator are cold. They are usually less saline than warm, as they flow from areas where there is a lot of precipitation, or from areas where ice melt has a desalinating effect. The cold currents of tropical latitudes are formed due to the rise of cold deep waters. Examples of warm currents are the Gulf Stream, Kuroshio, North Atlantic, North Pacific, North trade winds, South trade winds, Brazil, etc. Examples of cold currents are the West Winds (or Antarctic), Peru, California, Canary, Bengal and others.

The direction of ocean currents is greatly influenced by the Coriolis acceleration, and the direction of the wind does not coincide with the direction of the currents. The current deviates to the right in the Northern Hemisphere and to the left in the Southern Hemisphere from the direction of the wind by an angle of up to 45°.

Numerous measurements have shown that currents end at a depth not exceeding 300 m, but sometimes currents are found in deep layers. The reason for this is the different density of water. It can be caused by the pressure of a mass of water from above (for example, in places of a surge or its wind sweep), changes in water temperature and salinity. Density changes are the cause of constant vertical movements of water: lowering cold (or more salty) and rising warm (less salty).

In addition to wind currents, tidal currents are also widespread, changing direction 4 or 2 times a day; in narrow straits, the speed of these currents can reach 6 m/s (22 km/h).

The significance of ocean currents lies primarily in the redistribution of solar heat on Earth: warm currents contribute to an increase in temperature, while cold ones lower it. Currents have a huge impact on the distribution of precipitation on land. Territories washed by warm waters always have a humid climate, and cold - dry; in the latter case, no rains fall, only mists have a moisturizing effect. Living organisms are carried along with currents. This primarily applies to plankton, followed by large animals. When warm currents meet cold currents, ascending currents of water are formed, which raise deep water rich in nutrient salts. It favors the development of plankton, fish and marine animals, so these places are important fishing grounds.

So, the currents in the ocean are caused by the wind (wind ocean currents); arise due to different heights of the water level (runoff currents) and its different density (density currents). In all cases, the direction of the current is affected by the rotation of the Earth. Wind ocean currents can be classified by direction and temperature.

7. Zoning of the waters of the World Ocean (latitudinal zonality).

Latitudinal zonality is a regular change in physical and geographical processes, components and complexes of geosystems from the equator to the poles.

The primary reason for zoning is the uneven distribution of solar energy over latitude due to the spherical shape of the Earth and the change in the angle of incidence of the sun's rays on the earth's surface. In addition, latitudinal zonality also depends on the distance to the Sun, and the mass of the Earth affects the ability to hold the atmosphere, which serves as a transformer and redistributor of energy.

Of great importance is the inclination of the axis to the plane of the ecliptic, this determines the irregularity of the supply of solar heat by season, and the daily rotation of the planet causes the deviation of air masses. The result of the difference in the distribution of the radiant energy of the Sun is the zonal radiation balance of the earth's surface. Uneven heat input affects the location of air masses, moisture circulation and atmospheric circulation.

Zoning is expressed not only in the average annual amount of heat and moisture, but also in intra-annual changes. Climatic zoning is reflected in the runoff and hydrological regime, the formation of a weathering crust, and waterlogging. A great influence is exerted on the organic world, specific landforms. Homogeneous composition and high air mobility smooth out zonal differences with height.

In each hemisphere, 7 circulation zones are distinguished.

8. CURRENTS and macrocirculation of the World Ocean. Global Ocean Conveyor.

There are 11 major circulations (systems)

5 tropical

1. Sev-atlant

2. North Pacific

3. south atlan.

4.south pacific

5.south indian

6.equatorial-counterflow

7.atlantic and icelandic

8. Pacific Ocean (Aleudian)

9.Indian-monsoon system

10. polar (antarctic)

11. arctic

Ocean, or sea, currents are the forward movement of water masses in the oceans and seas, caused by various forces. Although the most significant cause of the currents is the wind, they can also form due to the unequal salinity of individual parts of the ocean or sea, the difference in water levels, and the uneven heating of different parts of the water areas. In the ocean there are eddies created by uneven bottoms, their size often reaches 100-300 km in diameter, they capture layers of water hundreds of meters thick.

If the factors that cause currents are constant, then a constant current is formed, and if they are episodic, then a short-term, random current is formed. According to the prevailing direction, the currents are divided into meridional, carrying their waters to the north or south, and zonal, spreading latitudinally. Currents in which the water temperature is higher than the average temperature for the same latitudes are called warm, lower - cold, and currents having the same temperature as the surrounding waters are called neutral.

Monsoon currents change their direction from season to season, depending on how the coastal monsoon winds blow. Countercurrents are moving towards the neighboring, more powerful and extended currents in the ocean.

The direction of currents in the World Ocean is influenced by the deflecting force caused by the rotation of the Earth - the Coriolis force. In the Northern Hemisphere, it deflects currents to the right, and in the Southern Hemisphere, to the left. The speed of currents on average does not exceed 10 m/s, and they extend to a depth of no more than 300 m.

In the World Ocean, there are constantly thousands of large and small currents that go around the continents and merge into five giant rings. The system of currents of the World Ocean is called circulation and is connected, first of all, with the general circulation of the atmosphere.

Ocean currents redistribute solar heat absorbed by masses of water. Warm water, heated by the sun's rays at the equator, they carry to high latitudes, and cold water from the polar regions, due to currents, gets to the south. Warm currents increase air temperature, while cold currents, on the contrary, decrease it. Territories washed by warm currents are characterized by a warm and humid climate, and those near which cold currents pass are cold and dry.

The most powerful current of the World Ocean is the cold current of the West Winds, also called the Antarctic circumpolar (from lat. cirkum - around). The reason for its formation are strong and stable westerly winds blowing from west to east over vast expanses of the Southern Hemisphere from temperate latitudes to the coast of Antarctica. This current covers a zone with a width of 2500 km, extends to a depth of more than 1 km and carries up to 200 million tons of water every second. On the path of the Western Winds there are no large land masses, and it connects in its circular flow the waters of three oceans - the Pacific, Atlantic and Indian.

The Gulf Stream is one of the largest warm currents in the Northern Hemisphere. It passes through the Gulf of Mexico (eng. Gulf Stream - the Gulf) and carries the warm tropical waters of the Atlantic Ocean to high latitudes. This giant stream of warm water largely determines the climate of Europe, making it soft and warm. Every second, the Gulf Stream carries 75 million tons of water (for comparison: the Amazon, the most full-flowing river in the world, is 220 thousand tons of water). At a depth of about 1 km under the Gulf Stream, a countercurrent is observed.

General scheme ocean surface water circulation

Sequential zonal change of macrocirculatory systems (large-scale movement system) is general pattern planetary water circulation.

In accordance with the zonal distribution of solar energy over the surface of the planet, the same type and genetically related circulation systems are created both in the ocean and in the atmosphere. The movement of water and air masses is determined by a pattern common to the atmosphere and hydrosphere: uneven heating and cooling of the Earth's surface. From this, macrocirculatory systems are more or less symmetrically located on both sides of the equator.

From it, in low latitudes, ascending currents (cyclonic eddies) and a decrease in masses arise, in other high latitudes, descending currents develop, an increase in masses (water, air) occurs, which is typical for anticyclonic vortex systems. The interaction of these systems is the circulation, the movement of the atmosphere and hydrosphere.

In tropical areas, the nature of the movements is anticyclonic, that is, the currents move clockwise, and in temperate and subpolar latitudes, the currents form a circulation directed counterclockwise, that is, they have a cyclonic character. Both cyclonic and anticyclonic eddies in the ocean correspond to climatic minima and atmospheric pressure maxima.

Anticyclonic and cyclonic gyres in each hemisphere are interconnected in such a way that the same flows (currents) are simultaneously the peripheral part of two gyres. For example, the North Atlantic Current is the northern branch of the tropical circulation and, at the same time, the southern branch of the cyclonic circulation of temperate and subpolar latitudes. Due to this, the cycles interact with each other. Therefore, the waters and carried by them various substances(salts, suspensions, etc.) are able, moving from system to system, to move along the entire length of the ocean. The transfer of masses, the exchange of energy and matter in the near-surface layer of the ocean occurs mainly in the latitudinal direction. Interlatitudinal exchange is carried out due to meridional exchange at the periphery of quasi-stationary water cycles. In low latitudes along the western coasts of the ocean, light tropical waters are carried out into the temperate zone. In temperate and subpolar latitudes, on the contrary, denser waters are transported along the western coasts, and less dense waters of the temperate and tropical zones are carried along the eastern coasts to the high latitudes of the World Ocean. The difference in water densities created in this way in the meridional direction increases the intensity of boundary currents in the coastal parts of anticyclonic and cyclonic systems.

The same macrocirculatory systems persist throughout the year. The seasonal variability of water circulation is characterized by a slight shift in the meridional direction in the cold season (in the winter of the northern hemisphere - to the north, in the summer of the northern hemisphere - to the south), as well as an increase in the intensity of circulation as a result of an increase in thermal contrasts between tropical and polar latitudes.

It has been established that the direct impact of the wind is limited to the upper layer with a thickness of about 30-50 m. Already in the subsurface layer between 50-100 and 200-300 m, the density (vertical) circulation plays a decisive role.

Speed ​​in the ocean vertical movements smaller than the horizontal ones by about three to five orders of magnitude, and in the atmosphere - by about two to three orders of magnitude. But their significance is great, because thanks to them, the exchange of surface and deep waters with energy, salts and nutrients takes place.

The most intensive vertical exchange takes place in the zones of convergence (convergence) and divergence (divergence) of water mass flows. In convergence zones, there is a sinking of water masses, in divergence zones - their rise to the surface, called upwelling. Divergence zones are formed in areas of cyclonic gyres, where centrifugal forces carry water from the periphery to the center and water rises in the central part of the gyre. Divergence occurs near the coast and where the wind from the land prevails (surface water surge). In anticyclone systems and in those coastal zones where the wind from the ocean dominates, water sinks.

The distribution of convergence and divergence zones is the same in different oceans. Slightly north of the equator is the equatorial convergence. On both sides of it, tropical divergences stretch along the hollows of tropical cyclonic systems, then subtropical convergences stretch along the axes of subtropical anticyclonic systems. High-latitude cyclonic systems correspond to polar divergences; the crest of the Arctic water cycle corresponds to Arctic convergence.

This is an ideal (averaged) scheme of surface ocean currents. The real, concrete situation is much more complicated, since the currents change speed, intensity, and sometimes direction. Some of them disappear from time to time. Ocean currents have a complex structure. Like rivers, they meander, forming smaller eddies (300-400 km in diameter).

The structure of surface ocean currents, which capture the upper hundreds of meters, basically coincides with the structure of atmospheric circulation. The exception is the westerly currents that close the gyres and do not necessarily go with the wind, plus intertrade countercurrents. Consequently, in nature there is a more complex than simple connection between wind and ocean currents. Real countercurrents. The total amount of solar energy absorbed by the World Ocean is determined to be 29.7∙1019 kcal/year, which is almost 80% of all radiation reaching the surface of the planet (36.5∙1019 kcal). In addition, the Ocean is the main accumulator of solar heat; it contains almost 21 times more than the amount of heat (76∙1022 kcal) that annually comes from the Sun to the Earth's surface. In a ten-meter layer of oceanic waters, there is 4 times more heat than in the entire atmosphere.

About 80% of the solar energy absorbed by the World Ocean is spent on evaporation - 26.8∙1019 kcal/year, which is only 3% of the heat accumulated by the World Ocean. Turbulent heat exchange with the atmosphere takes the rest of the absorbed solar radiation - 2.7∙1019 kcal/year. This is only 0.4% of the total heat content of the Ocean. Comparing the amount of incoming and outgoing amounts of heat exchange through the surface of the World Ocean with its heat content, we come to the conclusion that annually a surface layer about 50 m thick is involved in such an exchange with the atmosphere. Heat exchange of the most active 200-meter water column occurs in 3-4 years. That is, the distribution of energy largely depends on the structure of ocean currents (the Gulf Stream carries 22 times more heat than all the rivers of the globe).

Atmospheric movements are forced to adapt to the structure of oceanic movements, therefore oceanic and air currents form a single system that arises as a result of their adaptation to each other.

9. Water masses and hydrological fronts.

Water masses - These are large volumes of water that form in certain parts of the ocean and differ from each other in temperature, salinity, density, transparency, amount of oxygen and other properties. Unlike air masses, they great importance has vertical zonality. Depending on the depth, there are:

Surface water masses. They are formed under the influence of atmospheric processes and the influx of fresh water from the mainland to a depth of 200-250 m. Water temperature and salinity often change here, waves form, and their horizontal transport in the form of ocean currents is much stronger than the deep one. Surface waters have the highest content of plankton and fish;

Intermediate water masses. They have a lower limit within 500-1000 m. In tropical latitudes, intermediate water masses are formed under conditions of increased evaporation and a constant increase in salinity. This explains the fact that intermediate waters occur between 20° and 60° in the northern and southern hemispheres;

Deep water masses. They are formed as a result of mixing of surface and intermediate, polar and tropical water masses. Their lower limit is 1200-5000 m. Vertically, these water masses move extremely slowly, and horizontally they move at a speed of 0.2-0.8 cm / s (28 m / h);

Bottom water masses. They occupy the zone of the World Ocean below 5000 m and have a constant salinity, a very high density, and their horizontal movement is slower than vertical.

Depending on the origin, the following types of water masses are distinguished:

equatorial. Throughout the year, the water is strongly heated by the sun. Its temperature is 27-28°C. Seasonally, it changes by no more than 2°. These water masses have a salinity lower than in tropical latitudes, since they are desalinated by numerous rivers flowing into the ocean at equatorial latitudes, and by abundant atmospheric precipitation;

Tropical. They form in tropical latitudes. The water temperature here is 20-25°. The temperature of tropical water masses is greatly influenced by ocean currents. Warmer are the western parts of the oceans, where warm currents (see Ocean currents) come from the equator. The eastern parts of the oceans are colder, as cold currents come here. Seasonally, the temperature of tropical water masses varies by 4 °. The salinity of these water masses is much greater than that of the equatorial ones, since as a result of descending air currents, a high pressure area is established here and little precipitation falls;

Moderate water masses. In the temperate latitudes of the Northern Hemisphere, the western parts of the oceans are cold, where cold currents pass. The eastern regions of the oceans are warming up warm currents. Even in the winter months, the water in them has a temperature of 10°C to 0°C. In summer it varies from 10°С to 20°С. Thus, seasonally the temperature of moderate water masses varies by 10°C. They already have a change of seasons. But it comes later than on land, and is not so pronounced. The salinity of temperate water masses is lower than that of tropical ones, since not only rivers and atmospheric precipitation that fall here, but also icebergs entering these latitudes, have a desalination effect;

Polar water masses. Formed in the Arctic and off the coast of Antarctica. These water masses can be carried by currents to temperate and even tropical latitudes. In the polar regions of both hemispheres, water cools down to -2°C, but still remains liquid. A further decrease in temperature leads to the formation of ice. The polar water masses are characterized by an abundance of floating ice, as well as ice that forms huge ice expanses. In the Arctic Ocean, ice lasts all year and is in constant drift. In the Southern Hemisphere in areas of polar water masses sea ​​ice go into temperate latitudes much further than in the North. The salinity of the polar water masses is low, since ice has a strong desalination effect. There are no clear boundaries between the listed water masses, but there are transition zones - zones of mutual influence of neighboring water masses. They are most clearly expressed in places where warm and cold currents meet. Each water mass is more or less homogeneous in its properties, but in transitional zones these characteristics can change dramatically.

Water masses actively interact with the atmosphere: they give it heat and moisture, absorb from it carbon dioxide release oxygen.

When water masses with different properties meet, oceanographic fronts (convergence zones) are formed - they are formed at the junction of warm and cold surface currents and are characterized by the sinking of water masses. There are several frontal zones in the world ocean, but there are 4 main ones.

There are also zones of divergence in the ocean - zones of divergence of surface currents and the rise of deep waters: off the west coast of the continents died. Latitudes and over the thermal equator near the eastern continents. Such zones are rich in phytoplankton and zooplankton, fishing is good.