Water masses are large volumes of water formed in certain parts ocean and differ from each other in temperature, salinity, density, transparency, amount of oxygen contained and many other properties. Unlike air masses, they great value has vertical zoning. Depending on the depth, the following types are distinguished: water masses:

Surface water masses. They are located to a depth of 200-250 m. Here the water temperature and salinity often change, since these water masses are formed under the influence of precipitation and the influx of fresh continental waters. Waves and horizontal waves are formed in surface water masses. ocean currents. This type of water mass contains the highest content of plankton and fish.

Intermediate water masses. They are located to a depth of 500-1000 m. Basically, this type of mass is found in the tropical latitudes of both hemispheres and is formed under conditions of increased evaporation and a constant increase in salinity. Deep water masses. Their lower limit can reach up to 5000 m. Their formation is associated with the mixing of surface and intermediate water masses, polar and tropical masses. They move vertically very slowly, but horizontally at a speed of 28 m/hour.

Bottom water masses. They are located in the World Ocean below 5000 m, have constant salinity and very higher density.

Water masses can be classified not only depending on depth, but also by origin. IN in this case The following types of water masses are distinguished:

Equatorial water masses. They are well warmed by the sun, their temperature varies by season by no more than 2° and is 27 - 28°C. They are desalinated by heavy precipitation and rivers flowing into the ocean at these latitudes, so the salinity of these waters is lower than in tropical latitudes.

Tropical water masses. They are also well warmed by the sun, but the water temperature here is lower than in equatorial latitudes and amounts to 20-25°C. Seasonally, the temperature of waters in tropical latitudes varies by 4°. The temperature of the waters of this type of water mass is greatly influenced by ocean currents: the western parts of the oceans, where warm currents from the equator arrive, are warmer than the eastern parts, since cold currents arrive there. The salinity of these waters is significantly higher than that of the equatorial waters, since here, as a result of downward air currents, high blood pressure and there is little rainfall. Rivers also do not have a desalination effect, since there are very few of them in these latitudes.

Moderate water masses. By season, the water temperature of these latitudes differs by 10°: in winter the water temperature ranges from 0° to 10°C, and in summer it varies from 10° to 20°C. These waters are already characterized by a change of seasons, but it occurs later than on land and is not so pronounced. The salinity of these waters is lower than that of tropical waters, since the desalination effect is exerted by precipitation, rivers flowing into these waters, and icebergs entering these latitudes. Temperate water masses are also characterized by temperature differences between western and eastern parts oceans: the western parts of the oceans are cold, where cold currents pass, and the eastern areas are warmed warm currents.

Polar water masses. They form in the Arctic and off the coast of Antarctica and can be carried by currents to temperate and even tropical latitudes. Polar water masses are characterized by an abundance of floating ice, as well as ice that forms huge ice expanses. In the Southern Hemisphere in areas of polar water masses sea ​​ice they extend into temperate latitudes much further than in the North. The salinity of polar water masses is low, since floating ice has a strong desalination effect.

Between different types water masses differing in origin do not have clear boundaries, but there are transition zones. They are most clearly expressed in places where warm and cold currents meet. Water masses actively interact with the atmosphere: they give moisture and heat to it and absorb it carbon dioxide, release oxygen. The most characteristic properties of water masses are salinity and temperature.

As a result of dynamic processes occurring in the column of oceanic waters, a more or less mobile stratification of waters is established in it. This stratification leads to the separation of so-called water masses. Water masses are waters characterized by their inherent conservative properties. Moreover, water masses acquire these properties in certain areas and retain them throughout the entire space of their distribution.

According to V.N. Stepanov (1974), distinguish: surface, intermediate, deep and bottom water masses. The main types of water masses can, in turn, be divided into varieties.

Surface water masses are characterized by the fact that they are formed through direct interaction with the atmosphere. As a result of interaction with the atmosphere, these water masses to the greatest extent subject to: agitation, changes in the properties of ocean water (temperature, salinity and other properties).

Thickness surface masses on average is 200-250 m. They are also distinguished by the maximum intensity of transport - on average about 15-20 cm/s in the horizontal direction and 10 10-4 - 2 10-4 cm/s in the vertical direction. They are divided into equatorial (E), tropical (ST and YT), subarctic (SbAr), subantarctic (SbAn), Antarctic (An) and Arctic (Ap).

Intermediate water masses are released into polar regions with increased temperature, in temperate and tropical areas - with low or high salinity. Their upper boundary is the boundary with surface water masses. The lower boundary lies at a depth of 1000 to 2000 m. Intermediate water masses are divided into subantarctic (PSbAn), subarctic (PSbAr), North Atlantic (PSAt), North Indian Ocean (PSI), Antarctic (PAn) and Arctic (PAR) masses.

The main part of the intermediate subpolar water masses is formed due to the subsidence of surface waters in the subpolar convergence zones. The transport of these water masses is directed from the subpolar regions to the equator. IN Atlantic Ocean Subantarctic intermediate water masses pass beyond the equator and are distributed to approximately 20° N, in the Pacific - to the equator, in the Indian - to approximately 10° S. Subarctic intermediate waters in Pacific Ocean also reach the equator. In the Atlantic Ocean they quickly sink and get lost.

In the northern part of the Atlantic and Indian Oceans, intermediate masses have a different origin. They form on the surface in areas of high evaporation. As a result, excessively salty waters are formed. Due to its high density, these salty waters experience a slow sinking. To these are added dense salty waters from Mediterranean Sea(V North Atlantic) and from the Red Sea and the Persian and Oman Gulfs (in Indian Ocean). In the Atlantic Ocean, intermediate waters spread under the surface layer to the north and south from the latitude of the Strait of Gibraltar. They spread between 20 and 60° N latitude. In the Indian Ocean, the distribution of these waters goes south and southeast to 5-10° S. latitude.

The circulation pattern of intermediate waters was revealed by V.A. Burkov and R.P. Bulatov. It is characterized by an almost complete attenuation of wind circulations in the tropical and equatorial zones and a slight shift of subtropical gyres towards the poles. In this regard, intermediate waters from polar fronts spread to tropical and subpolar regions. The same circulation system includes subsurface equatorial countercurrents such as the Lomonosov Current.

Deep water masses are formed mainly at high latitudes. Their formation is associated with the mixing of surface and intermediate water masses. They usually form on shelves. Cooling and accordingly acquiring greater density, these masses gradually slide down the continental slope and spread towards the equator. Lower limit deep waters is located at a depth of about 4000 m. The intensity of circulation of deep waters was studied by V.A. Burkov, R.P. Bulatov and A.D. Shcherbinin. It weakens with depth. In the horizontal movement of these water masses main role play: southern anticyclonic gyres; circumpolar deep current in the Southern Hemisphere, which ensures the exchange of deep water between the oceans. The horizontal movement speeds are approximately 0.2-0.8 cm/s, and the vertical ones are 1 10-4 to 7 10O4 cm/s.

Deep water masses are divided into: circumpolar deep water mass Southern Hemisphere(GCP), North Atlantic (GSAt), North Pacific (GST), North Indian Ocean (GSI) and Arctic (GAr). Deep North Atlantic waters are characterized by increased salinity (up to 34.95%) and temperature (up to 3 °) and several increased speed movement. Their formation involves: waters of high latitudes, cooled on the polar shelves and sinking when mixing surface and intermediate waters, heavy salty waters of the Mediterranean, rather salty waters of the Gulf Stream. Their subsidence increases as they move to higher latitudes, where they experience gradual cooling.

Circumpolar deep waters are formed exclusively due to the cooling of waters in the Antarctic regions of the World Ocean. The northern deep masses of the Indian and Pacific oceans are of local origin. In the Indian Ocean due to the runoff of salty waters from the Red Sea and the Persian Gulf. In the Pacific Ocean, mainly due to the cooling of waters on the Bering Sea shelf.

Bottom water masses have the lowest temperatures and highest density. They occupy the rest of the ocean deeper than 4000 m. These water masses are characterized by very slow horizontal movement, mainly in the meridional direction. Bottom water masses differ somewhat large quantities vertical movement, compared to deep water masses. These values ​​are due to the influx of geothermal heat from the ocean floor. These water masses are formed due to the subsidence of overlying water masses. Among the bottom water masses most widespread use bottom Antarctic waters (PrAn). These waters are clearly visible by their lowest temperatures and relatively high oxygen content. The center of their formation is the Antarctic regions of the World Ocean and especially the Antarctic shelf. In addition, the North Atlantic and North Pacific bottom water masses (PrSAt and PrST) are distinguished.

Bottom water masses are also in a state of circulation. They are characterized predominantly by meridional transport in a northerly direction. In addition, in the northwestern part of the Atlantic there is a clearly defined current south direction, fed by the cold waters of the Norwegian-Greenland basin. The speed of movement of near-bottom masses increases slightly as they approach the bottom.

Water masses- these are large volumes of water formed in certain parts of the ocean and differing from each other in temperature, salinity, density, transparency, amount of oxygen and other properties. In contrast, , in them, is of great importance. Depending on the depth there are:

Surface water masses. They are formed under the influence of atmospheric processes and influx fresh water from the mainland to a depth of 200-250 m. Here, salinity often changes, and their horizontal transport in the form of ocean currents is much stronger than deep transport. In surface waters the most great content plankton and fish;

Intermediate water masses. They have a lower limit of 500-1000 m. In tropical latitudes, intermediate water masses are formed under conditions of increased evaporation and constant increase. 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 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 a zone below 5000 m and have constant salinity, very high density, and their horizontal movement is slower than vertical.

Depending on the origin there are following types water masses:

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. The western parts of the oceans are warmer, where warm currents (see) come from the equator. The eastern parts of the oceans are colder because 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 downward air currents little precipitation is established and falls here;

water masses. In temperate latitudes Northern Hemisphere The western parts of the oceans, where cold currents pass, are cold. The eastern regions of the oceans are warmed by warm currents. Even in winter months the water in them has a temperature from 10°C to 0°C. In summer it varies from 10°C to 20°C. Thus, the temperature of temperate water masses varies by 10°C between seasons. They are already characterized by the 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 the desalination effect is exerted not only by rivers and precipitation that fall here, but also by those entering these latitudes;

Polar water masses. Formed in and off the coast. These water masses can be carried by currents to temperate and even tropical latitudes. In the polar regions of both hemispheres, water cools to -2°C, but still remains liquid. Further decrease leads to the formation of ice. Polar water masses are characterized by an abundance of floating ice, as well as ice that forms huge ice expanses. The ice lasts all year and is in constant drift. In the Southern Hemisphere, in areas of polar water masses, they extend into temperate latitudes much further than in the Northern Hemisphere. The salinity of 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 transition zones these characteristics can change dramatically.

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

Education

What are water masses and their types? Main types of water masses

The total mass of all waters of the World Ocean is divided by experts into two types - surface and deep. However, such a division is very conditional. A more detailed categorization includes the following several groups, identified by the following criteria: territorial location.

Definition

First, let's define what water masses are. In geography, this designation refers to a fairly large volume of water that forms in one or another part of the ocean. Water masses differ from each other in a number of characteristics: salinity, temperature, as well as density and transparency. Differences are also expressed in the amount of oxygen and the presence of living organisms. We have given a definition of what water masses are. Now we need to look at their different types.

Water near the surface

Surface waters are those zones where their thermal and dynamic interaction with air occurs most actively. According to climatic features, inherent in certain zones, they are divided into separate categories: equatorial, tropical, subtropical, polar, subpolar. Schoolchildren who are collecting information to answer the question of what water masses are, also need to know about the depth of their occurrence. Otherwise, the answer in the geography lesson will be incomplete.

Surface water reach a depth of 200-250 m. Their temperature often changes, since they are formed by water under the influence of precipitation. Waves, as well as horizontal ocean currents, form in the surface water column. This is where greatest number fish and plankton. Between the surface and deep masses there is a layer of intermediate water masses. Their depth ranges from 500 to 1000 m. They are formed in areas of high salinity and high levels of evaporation.

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Deep water masses

The lower limit of deep water can sometimes reach 5000 m. This type of water mass is most often found in tropical latitudes. They are formed under the influence of surface and intermediate waters. For those interested in what water masses are and what their features are various types, it is also important to have an idea of ​​​​the speed of the current in the ocean. Deep water masses move very slowly in the vertical direction, but their horizontal speed can be up to 28 km per hour. The next layer is bottom water masses. They are located at depths of over 5000 m. This type is characterized by a constant level of salinity, as well as high level density.

Equatorial water masses

“What are water masses and their types” is one of the compulsory topics of the course secondary school. The student needs to know that waters can be classified into one group or another not only depending on their depth, but also on their territorial location. The first type mentioned in accordance with this classification is equatorial water masses. They are characterized high temperature(reaches 28°C), low level density, low oxygen content. The salinity of such waters is low. Above the equatorial waters there is a belt of low atmospheric pressure.

Tropical water masses

They are also quite well heated, and their temperature does not change by more than 4°C during different seasons. Great influence on this type waters are exerted by ocean currents. Their salinity is higher, because in this climatic zone A zone of high atmospheric pressure is established, and very little precipitation falls.

Moderate water masses

The salinity level of these waters is lower than that of others, because they are desalinated by precipitation, rivers, and icebergs. Seasonally, the temperature of water masses of this type can vary up to 10°C. However, the change of seasons occurs much later than on the mainland. Temperate waters vary depending on whether they are in the western or eastern regions of the ocean. The former, as a rule, are cold, and the latter are warmer due to warming by internal currents.

Polar water masses

Which water bodies are the coldest? Obviously, they are those located in the Arctic and off the coast of Antarctica. With the help of currents they can be carried to temperate and tropical areas. The main feature of polar water masses are floating blocks of ice and huge expanses of ice. Their salinity is extremely low. In the Southern Hemisphere, sea ice moves to temperate latitudes much more often than it does in the north.

Formation methods

Schoolchildren who are interested in what water masses are will also be interested in learning information about their formation. The main method of their formation is convection, or mixing. As a result of mixing, the water sinks to a considerable depth, where vertical stability is again achieved. This process can occur in several stages, and the depth of convective mixing can reach up to 3-4 km. The next method is subduction, or “diving.” At this method Forming masses of water, they sink due to the combined action of wind and surface cooling.

1. What determines the salinity of ocean waters?

World Ocean - main part hydrosphere - is a continuous water shell globe. The waters of the World Ocean are heterogeneous in composition and differ in salinity, temperature, transparency and other characteristics.

The salinity of water in the ocean depends on the conditions of evaporation of water from the surface and the influx of fresh water from the land surface and from atmospheric precipitation. Water evaporation occurs more intensely in equatorial and tropical latitudes and slows down in temperate and subpolar latitudes. If we compare the salinity of the northern and southern seas, we can establish that the water in southern seas more salty. The salinity of water in the oceans also varies depending on the geographical location, however, in the ocean the mixing of water occurs more intensely than in more closed seas, therefore the difference in the salinity of the ocean water masses will not be too sharp, as in the seas. The most saline (more than 37% o) are the ocean waters in the tropics.

2. What are the differences in ocean water temperature?

The water temperature in the World Ocean also varies depending on geographic latitude. In tropical and equatorial latitudes, the water temperature can reach +30 °C and above; in the polar regions it drops to -2 °C. With more low temperatures ocean water freezes. Seasonal changes in ocean water temperature are more pronounced in the temperate climate zone. The average annual temperature of the World Ocean is 3 °C higher than average temperature sushi. This heat is transferred to land using atmospheric air masses.

3. In what areas of the ocean does ice form? How do they affect the nature of the Earth and economic activity person?

The waters of the World Ocean freeze in the Arctic, subarctic and partly in temperate latitudes. The resulting ice cover affects the climate of the continents and makes it difficult to use cheap food in the north. maritime transport for transporting goods.

4. What is called water mass? Name the main types of water masses. What water masses are found in the surface layer of the ocean?

You will find a definition of the concept of water masses in the textbook (9).

Water masses, by analogy with air masses, are named according to the geographical zone in which they formed. Each water mass (tropical, equatorial, arctic) has its own characteristic properties and differs from the others in salinity, temperature, transparency and other characteristics. Water masses vary not only depending on geographical latitudes their formation, but also depending on the depth. Surface waters differ from deep and bottom waters. They have virtually no effect on deep and bottom waters sunlight and warmth. Their properties are more constant throughout the oceans, in contrast to surface pods, the properties of which depend on the amount of heat and light received. There is much more warm water on Earth than cold water. Residents of temperate latitudes spend their New Year holidays on the coasts of those seas and oceans where the water is warm and clean. Sunbathing under the hot sun, swimming in the salty and warm water, people regain strength and improve their health.