It has long been known that ocean waters cover most of the surface of our planet. They constitute a continuous water shell, which accounts for more than 70% of the entire geographical plane. But few people thought that the properties of ocean waters are unique. They have a huge impact on climate and economic activity of people.

Property 1. Temperature

Ocean waters can store heat. (about 10 cm deep) retain a huge amount of heat. Cooling, the ocean heats the lower layers of the atmosphere, due to which the average temperature of the earth's air is +15 °C. If there were no oceans on our planet, then the average temperature would hardly reach -21 ° C. It turns out that thanks to the ability of the oceans to accumulate heat, we got a comfortable and cozy planet.

The temperature properties of oceanic waters change abruptly. The heated surface layer is gradually mixed with more deep waters, resulting in a sharp temperature drop at a depth of several meters, and then a smooth decrease to the very bottom. The deep waters of the oceans have approximately the same temperature, measurements below three thousand meters usually show from +2 to 0 ° C.

As for surface water, then their temperature depends on the geographic latitude. The spherical shape of the planet determines the angle of incidence of the sun's rays on the surface. Closer to the equator, the sun gives off more heat than at the poles. So, for example, the properties of oceanic waters of the Pacific Ocean directly depend on the average temperature indicators. The surface layer has the highest average temperature, which is more than +19 °C. This cannot but affect the surrounding climate, and the underwater flora and fauna. This is followed by the surface waters of which, on average, are warmed up to 17.3 ° С. Then the Atlantic, where this figure is 16.6 ° C. And the lowest average temperatures are in the Northern Arctic Ocean- about +1 °С.

Property 2. Salinity

What other properties of ocean waters are being studied by modern scientists? they are interested in the composition of sea water. Ocean water is a cocktail of dozens of chemical elements, and salts play an important role in it. The salinity of ocean waters is measured in ppm. Designate it with the icon "‰". Promille means a thousandth of a number. It is estimated that a liter of ocean water has an average salinity of 35‰.

In the study of the oceans, scientists have repeatedly wondered what are the properties of ocean waters. Are they the same everywhere in the ocean? It turns out that salinity, like the average temperature, is not uniform. The indicator is influenced by a number of factors:

• amount precipitation- rain and snow significantly reduce the overall salinity of the ocean;
• stock of large and small rivers- salinity of the oceans washing the continents with large quantity full-flowing rivers, below;
• ice formation - this process increases salinity;
• melting ice - this process lowers the salinity of the water;
• evaporation of water from the surface of the ocean - salts do not evaporate with the waters, and salinity rises.

It turns out that the different salinity of the oceans is explained by the temperature of surface waters and climatic conditions. The highest average salinity is near the water of the Atlantic Ocean. However, the most salty point - the Red Sea, belongs to the Indian. The Arctic Ocean is characterized by the least indicator. These properties of the oceanic waters of the Arctic Ocean are most strongly felt near the confluence of the full-flowing rivers of Siberia. Here salinity does not exceed 10‰.

Interesting fact. The total amount of salt in the world's oceans

Scientists did not agree on how many chemical elements are dissolved in the waters of the oceans. Presumably from 44 to 75 elements. But they calculated that just an astronomical amount of salt is dissolved in the oceans, about 49 quadrillion tons. If all this salt is evaporated and dried, it will cover the surface of the land with a layer of more than 150 m.

Property 3. Density

The concept of "density" has been studied for a long time. This is the ratio of the mass of matter, in our case the oceans, to the volume occupied. Knowledge of the density value is necessary, for example, to maintain the buoyancy of ships.

Both temperature and density are heterogeneous properties of ocean waters. The average value of the latter is 1.024 g/cm³. This indicator was measured at average values ​​of temperature and salt content. However, on different areas The density of the world's oceans varies depending on the depth of measurement, the temperature of the site and its salinity.

Consider, for example, the properties of the oceanic waters of the Indian Ocean, and specifically the change in their density. This figure will be highest in the Suez and Persian Gulf. Here it reaches 1.03 g/cm³. In the warm and salty waters of the northwestern Indian Ocean, the figure drops to 1.024 g/cm³. And in the freshened northeastern part of the ocean and in the Bay of Bengal, where there is a lot of precipitation, the indicator is the lowest - about 1.018 g / cm³.

The density of fresh water is lower, which is why staying on the water in rivers and other fresh water bodies is somewhat more difficult.

Properties 4 and 5. Transparency and color

If you collect sea water in a jar, it will seem transparent. However, with an increase in the thickness of the water layer, it acquires a bluish or greenish tint. The change in color is due to the absorption and scattering of light. In addition, suspensions of various compositions affect the color of ocean waters.

bluish color clean water- the result of weak absorption of the red part of the visible spectrum. At a high concentration of phytoplankton in ocean water, it becomes blue-green or green color. This is due to the fact that phytoplankton absorbs the red part of the spectrum and reflects the green part.

The transparency of ocean water indirectly depends on the amount of suspended particles in it. AT field conditions transparency is determined by the Secchi disk. A flat disk, the diameter of which does not exceed 40 cm, is lowered into the water. The depth at which it becomes invisible is taken as an indicator of transparency in the area.

Properties 6 and 7. Sound propagation and electrical conductivity

Sound waves can travel thousands of kilometers under water. average speed distribution - 1500 m/s. This indicator for sea water is higher than for fresh water. The sound always deviates slightly from the straight line.

It has a higher electrical conductivity than fresh water. The difference is 4000 times. It depends on the number of ions per unit of water volume.

Geography teacher MBOU - secondary school No. 7 of the city of Mtsensk

Pikurova N.S.

Lesson type : learning new material

The purpose and objectives of the lesson:

expand existing knowledge about the main properties of sea water: temperature, salinity;

introduce students to new concepts;

continue the formation of the ability to work with a geographical map;

develop an interest in the subject.

develop research skills, the ability to analyze observed phenomena, formulate conclusions

Forms and methods: Explanatory and illustrative, partially exploratory; informational and illustrative; demonstration; independent work with the text of the textbook, conversation, work with the map.

Expected result of the lesson:

creative thinking schoolchildren,

the ability to acquire knowledge from various sources,

analyze the facts

make a generalization

express their own opinions.

Equipment:

presentation of the lesson “Properties of the waters of the oceans”,

textbook “Geography. Beginner course” 6th grade,

atlas 6th grade,

physical map of the world;

multimedia projector, screen.

During the classes

I. Organizational moment.

– Good afternoon! Guys, today we are again waiting for a journey through the endless world of the ocean. You will become members of the expedition of Captain Nemo, the hero of Jules Verne's novel "2000 Leagues Under the Sea".

II . Repetition. Checking homework.

But in order to travelCaptain Nemo has prepared a little test for you. The captain's boat will be waiting for you in the Indian Ocean at coordinates 30 aboutyush and 80 aboutvd. Each crew will try to get to this place from different points. We will draw lots. (Moscow, S.-P., Vladivostok) Crews led by captains are required to plan the navigation route of their ship in such a way as to cover the distance from the home port to the specified point in the shortest possible time. Route descriptions are recorded in the logbooks. (Time 4 min).

So, tell us about your routes.

III . Learning new material.

1 slide . All of you have successfully passed the test and the captain is glad to welcome you aboard his ship.

2 slide During our journey, you will learn about the properties of the world's oceans, such as salinity and temperature. We will conduct many observations and record the results in the logbook. So, let's go.

3 slide - Guys, you all know what water is. - What properties of water do you know?

4slide

Transparency

Has no smell

Fluidity

can simultaneously be in three states of aggregation

has low thermal conductivity

5slide - And the water is very good solvent Therefore, ocean water is a solution of various substances. It contains 73 of the 110 known chemical elements. Sodium and chlorine, which form table salt, make up more than 85% of all substances dissolved in ocean water. Aluminum, copper, silver, and gold have been found in ocean water, but in very small quantities.

Ocean water also contains dissolved gases, including oxygen. Why is oxygen needed?(for the life of marine organisms)

Also necessary for life are calcium, silicon and phosphorus, which make up the shells and skeletons of marine animals.

Have you tried sea water? What does she taste like?(salty)

It is correct to say bitter-salty. The bitter taste of ocean water comes from magnesium salts.

6 slide - One of the properties of water is salinity.

Salinity is the amount minerals in grams dissolved in 1 liter (1 kg) of water. It is expressed in ppm (thousandths of a number), indicated by the symbol ‰. Record the definition in your logbooks.

7 slide The average salinity of the World Ocean is 35 ‰. Let's try to bring the average salinity of ocean water in a liter jar. (It is necessary to add 35 g of salt).

Tell me, is there salt in the water you drink?

How to prove that there is salt in fresh water?(Salt can be seen by evaporating a few drops of water)

HeldAN EXPERIENCE. You need to drop a few drops of water on the glass and evaporate it by heating the glass on a spirit lamp. Salt will remain on the glass.

Also, scale remains at the bottom of pots and teapots - these are various salts.

The water is considered fresh1 liter of which contains less than 1 g of dissolved substances.

8 slide. Look at the map of the distribution of salinity in the world's oceans. Is the salinity of the water the same everywhere? (Not)

9 slide salinity distribution. You can see on the slide that the salinity in the seas is also not the same.

In the Red Sea, salinity is 42 ‰

salinity in the Black Sea - 18 ‰

Salinity in the Baltic Sea is 6-8 ‰

In the Gulf of Finland of the Baltic Sea, salinity is 3-4 ‰

In the Barents Sea, salinity is 35 ‰

Group work.

And now, try to bring the salinity of the ocean water of these seas.

1 crew - salinity of the Red Sea

2 crew - salinity of the Black Sea water

3 crew - salinity of the water of the Baltic Sea

Explain your actions. How did you get such salinity?

What problem do you think we will solve at the next stage? (Why salinity is different everywhere, what causes affect salinity?)

Guys, how can I change the salinity in my jar of water?

pour the water; 2) evaporate

Let's think about what processes in nature can pour water into the ocean?

( rain, rivers )

And what processes can remove water and leave salt? (Evaporation )

And where should you put a jar of water so that the water evaporates faster? (To a warm place ).

What other process can take water and leave salt?Ice )

10 slide - Let's conclude what factors affect the salinity of the oceans. (Salinity is affected by: precipitation, evaporation, number and fullness of rivers, ice formation ). Write it down in your logbooks.

11 slide. And now the crews do this task.

1 crew - explain why the Red Sea is the saltiest sea on Earth?

2 crew - explain why the salinity in the Black Sea is less than the average salinity of the ocean.

3 crew - explain why the salinity in the Baltic Sea is the smallest?

( Sample answer: In the marginal seas, the salinity is close to the average oceanic. AT Black Sea flows into many rivers that carry fresh water: Dnieper, Don, Danube, etc. The Baltic Sea is far from the equator, so there is little evaporation, many rivers flow into it, desalinating water. The full-flowing river Neva flows into the Gulf of Finland. Not a single river flows into the Red Sea, it is crossed by a tropic, which means there is little precipitation, and evaporation is large, because the sea is close to the equator )

Sailors learned about the approach of the coast by the salinity of the water. How could this be known?(Near the coast, the water is less salty, because rivers flow into the sea from the land, desalinating the water)

Why is the equator less saline than the tropics?(There is a lot of precipitation near the equator, little rainfall in the tropics)

12 slide - Look at the map, which ocean is the most salty?(Atlantic)

Which ocean has the least salinity?North Arctic )

13 slide. Average salinity of the oceans:

Pacific Ocean - 34.6%

Atlantic Ocean– 37.5%o

Indian Ocean - 34.8%

Arctic Ocean - 32%o

14slide - If all the salts dissolved in the waters of the World Ocean are evaporated and evenly distributed over the surface of the Earth, then our planet will be covered with a layer of salt 45 meters thick.

15 slide - Consider the following property of the waters of the World Ocean "Temperature".

Dear crew members, there was a disaster on the ship. In the captain's cabin there are all recorders from all instruments. The device that captures temperature changes at depth and on the surface of the water is out of order. It is urgent to draw graphs of changes in water temperature.

Group work.

1 crew - draw a graph of the change in water temperature on the surface, study the data on the temperature of the water and draw a conclusion about how it changes on the surface.

16 slide Surface water temperature:

0 c. br.: + 26С

30 s. br.: + 20С

60 s. sh. : + 5С

90 s. br.: - 1.5С

Conclusion : howfarther from the equator, the watercolder .

2 crew - draw a graph of the change in water temperature with depth. Examine the water temperature data and infer how the water temperature changes with depth.

0 m: + 20С

200 m: + 10С

1000 m: + 3С

2000 m: + 2С

5000 m: + 2С

Conclusion : temperature with depthgoing down . The water is heating upsunny rays. Rays only penetrateupper layers of water. Below a depth of 1000 m, the temperature remainsequally low . Sun rays do not penetratedepth .

17 slide . So, let's summarize again, what does the temperature of the water depend on?

18 slide (from the climate) Record the output in your logbooks

3 crew - study the temperature distribution map over the surface of the water and say which of the oceans is the warmest, coldest and conclude why? Word 3 to the crew.

19 slide. The highest surface water temperature in the Pacific Ocean (+19.4°C), Indian (+17.3°C), Atlantic (+16.5°C) oceans, the most low temperature water in the Arctic Ocean (-1°C).

20 slide. The average temperature of the waters of the World Ocean is 3.5 ° С

On the surface of the ocean, the highest temperature was recorded in the shallow Persian Gulf of the Indian Ocean (above + 35С), the coldest water in the Weddell Sea in Antarctica - 1 - 2С.

Ocean water freezes at temperatures- 2С

The higher the salinity of water, the lower its freezing point.

IV . Lesson summary

What we learned today about the salinity and temperature of the waters of the oceans.

21 slide. Complete the sentences "I know that..."

salinity is measured in ppm

salinity in the seas and oceans is not the same

salinity depends on evaporation, precipitation, rivers flowing into the sea

fresh water has a salinity of 1 ‰

the most salty sea - Red

surface waters are heated by the rays of the sun

the deeper, the colder the water

the water temperature drops to a depth of 1000 m, then remains constant

the temperature near the equator is +26…+27С

at the poles the temperature is -1С

salt water freezes at -2°C

22 slide. v. Homework. § 26, ass. 3

23 slide. Lesson summary

1. Salinity. Ocean water is a solution containing all chemical elements. There is especially a lot of chlorine, sodium, magnesium, sulfur in ocean water, less - bromine, carbon, strontium, boron. The content of other elements is negligible - less than 1%.

The total amount of salts in the ocean is 5 . 10 17 tons, they can cover the entire Earth with a layer of 45 m thick. Most of all in the ocean are sodium (NaCl) and magnesium (MgCl) salts, which give the water a salty bitter taste.

The average salinity of the World Ocean is 35% o, i.e. 1 liter of ocean water contains 35 g of salts. Salinity depends on the ratio of atmospheric precipitation and evaporation, runoff from land (rivers), melting ice. Latitudinal zonality is manifested in the distribution of salinity on Earth. In the equatorial latitudes, the salinity is somewhat less than the average (about 34 o / oo), in tropical latitudes it increases to 37 o / oo. Further north and south, salinity decreases: in temperate latitudes to 35 o / oo, and in polar latitudes to 33-32 o / oo.

The latitudinal zonality in the distribution of salinity is disturbed by ocean currents. The Atlantic Ocean is considered to be the most saline - almost 35.5 o / oo, the least salty - the Arctic Ocean - about 32 o / oo (off the coast of Asia - only 20 o / oo). The most saline are the Persian Gulf (39 o / oo), the Red Sea (42 o / oo), the Mediterranean Sea (39 o / oo).

At depths of more than 1500 m, the salinity of the World Ocean is unchanged - about 34.9 o / oo.

2. Temperature. The temperature of the entire mass of ocean water is approximately +4 o C. Water is the warmest body on Earth, so the ocean slowly heats up and slowly cools down. As already mentioned, the ocean is a powerful heat accumulator.

The average temperature of the surface waters of the ocean is +17 o C (the average annual temperature of the land is +14 o C). The highest water temperatures in the northern hemisphere are in August, the lowest - in February (in the southern hemisphere vice versa).

Surface water temperature is zonal. In equatorial latitudes, the temperature is +27 o - +28 o C all year round, in tropical - +15 o - +25 o C, in temperate - 0 o - +10 o C, in polar - 0 o - -2 o C. Most the warmest is the Pacific Ocean (average temperature +19 o C), and the warmest parts of the World Ocean are the Red Sea (+32 o C) and the Persian Gulf (+35 o C).

Daily and annual fluctuations in water temperature are small: daily - about 1 o C, annual in temperate latitudes - 5-10 o C.

Significant temperature changes occur only in upper layers ocean water - 200-1000 m, deeper the temperature is +4 o +5 o C, near the bottom in polar latitudes - about 0 o, in equatorial latitudes - +2 o +3 o C.

3. Ice in the ocean. The freezing point of water depends on its salinity. The formation of ice begins with the appearance of fresh crystals, which then freeze. At the same time, brine drops remain in the space between the crystals, so the ice is salty. The brine gradually flows down between the crystals, and over time the ice is desalinated.

With calm water, an acicular structure of ice is formed, with stirring, a spongy structure. The ice is 9/10 submerged.

Salt ice is less durable than fresh ice, but it is more plastic and viscous.

The initial stage of ice formation is ice crystals. Further, an ice film is formed - lard, when snow falls, snow is formed. A strip of ice grows along the coast - fast ice. Adult ice has a thickness of 50-70 cm or more.

In the polar latitudes of the northern hemisphere, the ice formed in winter does not have time to melt over the summer. Among polar ice There are annuals and perennials. Thickness first-year ice in the Arctic 2-2.5 m, in the Antarctic 1-1.5 m. Multi-year ice has a thickness of 3-5 m or more.

When compressed, the ice forms hummocks. The non-moving ice is only near the shore, the rest is drifting. Perennial layers of drifting ice in the Arctic are called pack ice (thickness 5 m or more). These ices occupy about 75% total area ice in the Arctic Ocean (there are none in the Southern Ocean).

When ice melts, lakes are formed on it - snowfields, then, at temperatures above 0 ° C, polynyas form, etc.

Except sea ​​ice, in the ocean can be river ice carried out by rivers in spring, as well as continental ice - icebergs.

Ice covers almost 15% of the entire water area of ​​the World Ocean. In the Arctic, ice reaches its greatest distribution by April-May, and the least - by the end of August. In Antarctica in winter (from May to October) ice circles surround the mainland, and in summer - this ring (January-February) is destroyed.

Icebergs reach 50 o s. in the northern hemisphere and 30 o S. in the southern hemisphere. An iceberg 170 km long and 100 m high was discovered in the Wedell Sea.

4. Density. As the salinity of water increases, its density increases. This is facilitated by the cooling of water, as well as evaporation, the formation of ice. Cold water has a higher density than warm water, so it sinks. The average density of ocean water is approximately 1; it increases from the equator to the poles and deep into the ocean.

5. Pressure. The air exerts tremendous pressure on the ocean. In addition, the water itself creates pressure, and the deeper it is, the greater the pressure. For every 10 m of depth, the pressure increases by 1 atm. All processes at great depths are carried out under strong pressure.

6. Transparency. The least transparency of water near the coast. It also decreases during the plankton period. AT clear water sunlight passes to a depth of about 600 m, then complete darkness. The most transparent are the central parts of the oceans and the most transparent is the Sargasso Sea.

7. Color. The clear water column of the ocean has a blue or Blue colour("the color of the oceanic desert"). The presence of plankton gives the water a greenish tint, various impurities - yellowish-green (near the mouth of the rivers, the water can even be brown).

8. Gas composition. Gases are always dissolved in ocean water. The higher the temperature and salinity, the less gases can dissolve in water. Gases enter the water from the atmosphere, during chemical and biological processes in the ocean, with river water, during underwater eruptions. Oxygen dissolved in water carbon dioxide, hydrogen sulfide, ammonia, methane.

Remember

• How does water heat up and cool down compared to land? What color on physical maps depict the surface of the oceans?

Color and transparency. A small layer of ocean water appears colorless and transparent. But its large thicknesses are blue and even blue. More transparent water in the open ocean. Near the coast, its color and transparency are influenced by various impurities that give the water different shades.

Some seas got their names because of the special color of the water: Red, Yellow, White. The corresponding color of the water in the Red Sea occurs during the period rapid flowering algae. The water in the Yellow Sea is colored with yellow silt, which rivers carry out from the land. The White Sea owes its name to the ice that covers it for most of the year.

Water temperature- one of the most important properties of the oceans. You already know that water heats up slowly, but it also cools slowly. Therefore, in surface layer Ocean waters accumulate a huge amount of heat in summer. In winter, the water cools and gives off heat to the air. Thus, the oceans regulate the temperature on earth's surface. However, the thickness of the heated water layer is no more than 200 m. Deeper, the temperature drops rapidly and always remains constant -2-3 °C.

Surface water temperature depends on the amount of incoming solar heat, therefore, it decreases from the equator to the poles (Fig. 121). The water temperature also changes with the seasons. In the Northern Hemisphere, it is the largest in August, and the smallest in February, in the Southern Hemisphere - on the contrary.

Rice. 121. The temperature of the surface waters of the ocean

At what latitudes are the average annual surface water temperatures the highest? What is the average annual water temperature in the Arctic Ocean and near Antarctica? Why does surface water temperature decrease from the equator to the poles?

The average annual temperature of the surface waters of the entire World Ocean is +17°С. The warmest oceans are the Pacific and Indian (average temperatures are +19 and +17°C, respectively). The warmest part of the World Ocean is the Persian Gulf. Here the water temperature in summer reaches +32°С. The lowest water temperature in the Arctic Ocean and around Antarctica. Therefore, here the surface of the oceans is covered with ice.

Follow Figure 121 for the boundary of ice distribution in the Northern and Southern Hemispheres. To what latitude does the ice reach?

Salinity. Sea water has a bitter-salty taste due to the salts dissolved in it. Depending on their number, the salinity of the water is judged.

Salinity is the amount of salts in grams dissolved in 1 liter (kg) of water.

Salinity is determined in ppm (from Latin "thousandth share"). The average salinity of ocean waters is 35 g of salts per 1 liter of water, i.e. 35 ppm.

The total amount of dissolved substances in the oceans is enormous. If all the water is evaporated, they will cover the bottom of the oceans with a layer of 64 m. And if all the sea salt is distributed over the surface of the land, you get a layer 153 m thick!

Ocean water is often referred to as "liquid ore" because almost all the substances found on Earth are dissolved in it. Salt predominates in it, which gives the water a salty taste. The content of other substances is very small. Therefore, it is not yet profitable to extract them from sea water.

The salinity of surface waters is affected by the inflow of river waters, ice melting, and currents. However, the main reason for the change in salinity is the amount of precipitation and air temperature. Where there is a lot of precipitation, the salinity of the water decreases. In areas with high temperatures and with little rainfall, salinity increases as water evaporates and salts remain in the ocean. Thus, salinity, as well as the temperature of surface waters, varies depending on the geographical latitude (Fig. 122).

Rice. 122. Salinity of surface waters of the ocean

The salinity of the seas, especially inland ones, may differ from the salinity of the waters open ocean. So, for example, salinity in the Red Sea reaches 42 ppm, and in the Baltic does not exceed 12 ppm. Explain these differences. What is the salinity of surface waters around the equator? Why is the lowest salinity of surface waters observed near the poles?

Many other properties of water depend on temperature and salinity. Cold and more saline water is denser and heavier than warm and less salty water. Differences in the density of water in the oceans lead to its constant mixing. Because ocean water is salty, it freezes at temperatures below 0°C. At a salinity of 35 ppm, water freezes at -2°C. In addition, salinity is important for marine organisms: many of them can only live in water of a certain salinity.

In sea water, in addition to salts, gases are also dissolved. Among them, the most important is oxygen, which is necessary for the respiration of marine organisms. Its content in water depends on temperature: the colder the water, the more oxygen it contains. Therefore, in the cold waters of temperate and subpolar latitudes more fish than in the tropics. The upper layers of water are richer in oxygen than the lower ones. If there are many animals in the water column, there may be a lack of oxygen due to its high use for respiration.

Questions and tasks

1. Why is the Yellow Sea so named? Find it on the map in the atlas and name the rivers that flow into it.
2. Why is the temperature and salinity of ocean surface waters variable?
3. What is the significance of the heating and cooling of surface waters for the nature of the Earth?
4. Why is ocean water called "liquid ore"?

1. Salinity. Ocean water is a solution containing all chemical elements. There is especially a lot of chlorine, sodium, magnesium, sulfur in ocean water, less - bromine, carbon, strontium, boron. The content of other elements is negligible - less than 1%.

The total amount of salts in the ocean is 5 . 10 17 tons, they can cover the entire Earth with a layer of 45 m thick. Most of all in the ocean are sodium (NaCl) and magnesium (MgCl) salts, which give the water a salty bitter taste.

The average salinity of the World Ocean is 35% o, i.e. 1 liter of ocean water contains 35 g of salts. Salinity depends on the ratio of atmospheric precipitation and evaporation, runoff from land (rivers), melting ice. Latitudinal zonality is manifested in the distribution of salinity on Earth. In the equatorial latitudes, the salinity is somewhat less than the average (about 34 o / oo), in tropical latitudes it increases to 37 o / oo. Further north and south, salinity decreases: in temperate latitudes to 35 o / oo, and in polar latitudes to 33-32 o / oo.

The latitudinal zonality in the distribution of salinity is disturbed by ocean currents. The Atlantic Ocean is considered to be the most saline - almost 35.5 o / oo, the least salty - the Arctic Ocean - about 32 o / oo (off the coast of Asia - only 20 o / oo). The most saline are the Persian Gulf (39 o / oo), the Red Sea (42 o / oo), the Mediterranean Sea (39 o / oo).

At depths of more than 1500 m, the salinity of the World Ocean is unchanged - about 34.9 o / oo.

2. Temperature. The temperature of the entire mass of ocean water is approximately +4 o C. Water is the warmest body on Earth, so the ocean slowly heats up and slowly cools down. As already mentioned, the ocean is a powerful heat accumulator.

The average temperature of the surface waters of the ocean is +17 o C (the average annual temperature of the land is +14 o C). The highest water temperatures in the northern hemisphere are in August, the lowest - in February (in the southern hemisphere vice versa).

Surface water temperature is zonal. In equatorial latitudes, the temperature is +27 o - +28 o C all year round, in tropical - +15 o - +25 o C, in temperate - 0 o - +10 o C, in polar - 0 o - -2 o C. Most the warmest is the Pacific Ocean (average temperature +19 o C), and the warmest parts of the World Ocean are the Red Sea (+32 o C) and the Persian Gulf (+35 o C).

Daily and annual fluctuations in water temperature are small: daily - about 1 o C, annual in temperate latitudes - 5-10 o C.

Significant temperature changes occur only in the upper layers of the ocean water - 200-1000 m, deeper the temperature is +4 o +5 o C, near the bottom in polar latitudes - about 0 o, in equatorial latitudes - +2 o +3 o C.

3. Ice in the ocean. The freezing point of water depends on its salinity. The formation of ice begins with the appearance of fresh crystals, which then freeze. At the same time, brine drops remain in the space between the crystals, so the ice is salty. The brine gradually flows down between the crystals, and over time the ice is desalinated.

With calm water, an acicular structure of ice is formed, with stirring, a spongy structure. The ice is 9/10 submerged.

Salt ice is less durable than fresh ice, but it is more plastic and viscous.

The initial stage of ice formation is ice crystals. Further, an ice film is formed - lard, when snow falls, snow is formed. A strip of ice grows along the coast - fast ice. Adult ice has a thickness of 50-70 cm or more.

In the polar latitudes of the northern hemisphere, the ice formed in winter does not have time to melt over the summer. Among the polar ice there are annual and perennial. The thickness of first-year ice in the Arctic is 2-2.5 m, in the Antarctic 1-1.5 m. multi-year ice have a thickness of 3-5 m or more.

When compressed, the ice forms hummocks. The non-moving ice is only near the shore, the rest is drifting. Perennial layers of drifting ice in the Arctic are called pack ice (thickness 5 m or more). These ices occupy about 75% of the total ice area in the Arctic Ocean (there is none in the Southern Ocean).

When ice melts, lakes are formed on it - snowfields, then, at temperatures above 0 ° C, polynyas form, etc.

In addition to sea ice, the ocean can contain river ice carried by rivers in spring, as well as continental ice - icebergs.

Ice covers almost 15% of the entire water area of ​​the World Ocean. In the Arctic, ice reaches its greatest distribution by April-May, and the least - by the end of August. In Antarctica, in winter (from May to October), ice circles surround the mainland in a ring, and in summer, this ring (January-February) is destroyed.

Icebergs reach 50 o s. in the northern hemisphere and 30 o S. in the southern hemisphere. An iceberg 170 km long and 100 m high was discovered in the Wedell Sea.

4. Density. As the salinity of water increases, its density increases. This is facilitated by the cooling of water, as well as evaporation, the formation of ice. Cold water has a greater density than warm, so it sinks down. The average density of ocean water is approximately 1; it increases from the equator to the poles and deep into the ocean.

5. Pressure. The air exerts tremendous pressure on the ocean. In addition, the water itself creates pressure, and the deeper it is, the greater the pressure. For every 10 m of depth, the pressure increases by 1 atm. All processes at great depths are carried out under strong pressure.

6. Transparency. The least transparency of water near the coast. It also decreases during the plankton period. In clear water, sunlight passes to a depth of about 600 m, then complete darkness. The most transparent are the central parts of the oceans and the most transparent is the Sargasso Sea.

7. Color. The clear water column of the ocean has a blue or blue color (“the color of the oceanic desert”). The presence of plankton gives the water a greenish tint, various impurities - yellowish-green (near the mouth of the rivers, the water can even be brown).

8. Gas composition. Gases are always dissolved in ocean water. The higher the temperature and salinity, the less gas can dissolve in water. Gases enter the water from the atmosphere, during chemical and biological processes in the ocean, with river water, during underwater eruptions. Oxygen, carbon dioxide, hydrogen sulfide, ammonia, methane are dissolved in water.

Ocean water movement

The water in the oceans is in constant motion. This ensures mixing of water, redistribution of heat, salinity and gases.

Consider the individual movements of water.

1. Wave movements (waves). main reason the occurrence of waves is the wind, but they can also be caused by a sharp change atmospheric pressure, earthquake, volcanic eruptions on the coast and the ocean floor, tidal force.

The highest part of the wave is called the crest; the deepest part is the sole. The distance between two adjacent crests (soles) is called the wavelength - (l).

The height of the wave (H) is the excess of the crest of the wave above its sole. The wave period (t) is the period of time during which each point of the wave moves a distance equal to its length. Velocity (n) is the distance traveled per unit time by any point of the wave.

Distinguish:

a) wind waves - under the influence of the wind, the waves grow simultaneously in height and length, while the period (t) and speed (n) increase; as the waves develop, they change appearance and sizes. At the stage of wave attenuation, long gentle waves are called swell. Wind waves have a significant destructive force, thereby forming the relief of the coast. The average water height of wind waves in the ocean is 3-4 m (maximum up to 30 m), in the seas the height of the waves is less - maximum no more than 9 m. With increasing depth, the waves quickly fade.

b) tsunamis - seismic waves covering the entire water column, occur during earthquakes and underwater volcanic eruptions. Tsunamis have a very long wavelength, their height in the ocean does not exceed 1 m, so they are not noticeable in the ocean. But on the coasts, in the bays, their height increases to 20-50 m. The average speed of tsunami propagation is from 150 km/h to 900 km/h. Before the arrival of a tsunami, the water usually recedes from the coast for several hundred meters (up to 1 km) within 10-15 minutes. Large tsunamis are rare. Most of them are on the shores of the Pacific Ocean. The tsunami is associated with enormous destruction. The strongest tsunami occurred in 1960 as a result of an earthquake in the Andes, on the coast of Chile. At the same time, the tsunami spread across Pacific Ocean to the coast North America(California), New Zealand, Australia, Philippine, Japanese, Kuril, Hawaiian Islands and Kamchatka. The tsunami reached the shores of Japan and Kamchatka almost a day after the earthquake.

c) tidal waves (tides) arise as a result of the influence of the Moon and the Sun. Tides are an extremely complex phenomenon. They are constantly changing, so they cannot be considered periodic. For navigation, special tables of "tides" have been created, which is especially important for port cities located in the lower reaches of rivers (London on the River Thames, etc.). The energy of tidal waves is used by building PES (they are in Russia, France, USA, Canada, China).

2. Currents of the World Ocean (sea currents). These are horizontal movements of water in the oceans and seas, characterized by a certain direction and speed. Their length is several thousand kilometers, width - tens, hundreds of kilometers, depth - hundreds of meters.

The main cause of currents in the ocean is the wind. Other reasons include tide-forming forces, gravity. All currents are affected by the Coriolis force.

Currents can be classified according to a number of features.

I. Currents are distinguished by their origin.

1) frictional - arise under the action of moving air on the surface of the water:

a) wind - caused by temporary winds (seasonal),

b) drift - caused by constant winds (prevailing);

2) gravitational - arise under the influence of gravity:

a) sewage - flow from areas of excess water and tend to level the surface,

b) density - are the result of differences in the density of water at the same depth;

3) tidal - arise under the action of tide-forming forces; cover the entire water column.

II. Currents are distinguished by duration

1) constant - they always have approximately the same direction and speed (North trade wind, South trade wind, etc.);

2) periodic - periodically change direction and speed (monsoon currents in the Indian Ocean, tidal currents, and others);

3) temporary (episodic) - there are no regularities in their changes; they change frequently, most often as a result of the action of the wind.

III. By temperature, one can distinguish (but relatively) currents

1) warm - for example, the temperature of the North Atlantic Current is +6 o C, and the surrounding water is +4 o C;

2) cold - for example, the temperature of the Peruvian current is +22 ° C, the surrounding water is +28 ° C;

3) neutral.

Warm currents, as a rule, go from the equator to the poles, cold ones vice versa. Warm currents are usually saltier than cold ones.

IV. Depending on the depth of the location, currents are distinguished

1) superficial,

2) deep,

3) bottom.

At present, a certain system of ocean currents has been established, primarily due to the general circulation of the atmosphere. Their scheme is as follows. In each hemisphere, on both sides of the equator, there are large circulations of currents around permanent subtropical baric maxima (in these latitudes, areas of high atmospheric pressure are formed): in the northern hemisphere clockwise, in the southern hemisphere counterclockwise. Between them there is an equatorial countercurrent from west to east. In temperate and subpolar latitudes of the northern hemisphere, small rings of currents are observed around the baric minimum (areas of low atmospheric pressure: the Icelandic minimum and the Aleutian minimum). In similar latitudes of the southern hemisphere, there is a current from west to east around Antarctica (the current of the Western winds).

The most stable currents are the North and South trade winds (equatorial) currents. Off the eastern shores of the continents in tropical latitudes, warm sewage currents: the Gulf Stream, Kurosivo, Brazilian, Mozambique, Madagascar, East Australian.

In temperate latitudes, under the influence of constant westerly winds, there are warm North Atlantic and North Pacific currents and a cold current of westerly winds (Western Drift). Off the western coasts of the continents in tropical latitudes, cold compensatory currents are observed: the California, Canary, Peruvian, Benguela, and Western Australian currents.

In small current rings, one should name the warm Norwegian and cold Labrador currents in the Atlantic and the Alaska and Kurile-Kamchatka currents in the Pacific Ocean.

In the northern part of the Indian Ocean, the monsoon circulation generates seasonal wind currents: in winter - from east to west, in summer - vice versa (in summer it is a cold Somali current).

In the Arctic Ocean, the main direction of water and ice is from east to west, towards the Greenland Sea. The Arctic is replenished with water from the Atlantic in the form of the North Cape, Svalbard, Novaya Zemlya currents.

The importance of sea currents for the climate and nature of the Earth is great. Currents disrupt the zonal temperature distribution. Thus, the cold Labrador Current contributes to the formation of ice-tundra landscapes on the Labrador Peninsula. And the warm currents of the Atlantic make most of Barents Sea. Currents also affect the amount of precipitation: warm currents contribute to the flow of precipitation, cold ones do not. Sea currents also help to mix water and transport nutrients; with their help, the migration of plants and animals occurs.

life in the ocean

In the oceans, life exists everywhere. According to the conditions of existence in the ocean, 2 areas are distinguished:

1) pelagial (water column),

2) benthal (bottom) -

a) littoral (coastal part of the bottom to a depth of 200 m),

b) abyssal (deep part).

organic world The ocean consists of 3 groups:

1) benthos - inhabitants of the bottom (plants, worms, molluscs, crabs, etc.),

2) plankton - inhabitants of the water column that are not able to move independently (protozoa, bacteria, algae, jellyfish, etc.),

3) nekton - the inhabitants of the waters. Free-swimming (fish, whales, dolphins, seals, squids, sea snakes and turtles, etc.).

Green plants can develop only where there is enough light for photosynthesis (up to a depth of no more than 200 m). Organisms that do not need light inhabit the entire water column.

Plankton is subdivided into phytoplankton and zooplankton. Most of the mass of living matter in the ocean is phytoplankton (under favorable conditions, its number can double in a day). Phytoplankton inhabits mainly the upper hundred-meter layer of water. The average mass of phytoplankton is 1.7 billion tons. The most common form of phytoplankton is diatoms, of which there are about 15,000 species. Phytoplankton is the main food for most marine organisms. Places of abundant development of phytoplankton are places rich in life.

The distribution of life in the ocean has a zonal character:

- in the polar latitudes, the conditions for phytoplankton are unfavorable, so they are poor in life (cold-loving fish and seals live here);

- in the subpolar latitudes, phytoplankton develops in summer, they feed on zooplankton, they, in turn, fish, whales, so in summer there are a lot of cod, perch, haddock, herring and other fish;

- in temperate latitudes, the most favorable conditions are formed, these are the most productive zones of the ocean: an abundance of phyto- and zooplankton, an abundance of herring, cod, flounder, halibut, saffron cod, salmon, sardine, tuna, anchovy and other fish;

- in subtropical and tropical latitudes, the conditions for life are unfavorable: high salinity, little oxygen, a small amount of plankton and fish; only brown algae - sargasso are common here;

– conditions are improving in equatorial latitudes, so the amount of plankton and fish is increasing here; a lot of corals.

The ocean has the following resources: biological (90% fish, mammals, molluscs, algae), mineral (oil, gas, coal, iron and manganese ores, tin, phosphorites, salt, etc.) and energy.