Tasks research work: Tasks of the research work: Tasks of the research work: Tasks of the research work: Explain the causes of the formation of ocean currents Explain the causes of the formation of ocean currents Get acquainted with the direction of surface and deep ocean currents Get acquainted with the direction of surface and deep ocean currents Learn to distinguish between warm and cold currents according to the description and on the map Learn to distinguish between warm and cold currents according to the description and on the map Name and show on the map large ocean currents Name and show on the map large ocean currents
Complete test tasks Complete test tasks. 1. Name the reason why the tides are formed: r) the attraction of the waters of the Ocean by the Moon; a) the wind d) earthquakes. 2. Does the water move when the sea is rough? e) no; i) yes. 3. The stronger the wind and the deeper the sea, the h) the waves are larger; b) the waves are smaller; 4. Cause of tsunami formation: a) wind; i) the attraction of the waters of the Ocean by the Moon; e) underwater earthquakes. 5. Where do earthquakes most often occur? e) on the plains; y) in the mountains; m) in seismic belts. 6. From the listed names of geographical objects, name the gulf e) Bering; i) Bengali; m) Gibraltar. 7. Of the listed seas, the most salty is e) the Mediterranean; i) Red; i) Baltic.
“My plan for the lesson and my progress” Last name, first name _______________________________________________ Testing Work in the contour map Recovery of writing Participation in the lesson 5 points - 7 answers 4 points - 6 answers 3 points - answers For each marked course - 1 point 1 task - 1 point Task 2 - 1 point Task 3 - 1 point Task 4 - 2 points Task 5 - 2 points 3 points - actively and independently worked in the lesson 2 points - worked independently in the lesson and helped a friend 1 point - completed all the tasks correctly and independently My progress ? ? ? ? The maximum number of points is 19 Evaluation criterion: "5" points "4" points My total points - My mark -
Oceanic (sea) currents - the movement of water in the ocean or sea in a horizontal direction 1. Constant winds. 2. Relief of the ocean floor. 3. Outlines of the continents.. 4. Rotation of the Earth around its axis. Object of research work: Causes of the formation of currents in the ocean
The temperature of the flowing water is several degrees above the temperature of the surrounding water The temperature of the flowing water is several degrees below the temperature of the surrounding water problem question. The temperature of the waters of the Peruvian current off the coast South America is 22C o, and the North Atlantic 2 C o. The first is considered - cold, and the second - warm. Why?
Large ocean currents OceanWarm currentsCold currents PacificNorth trade wind South trade wind Kurocio North Pacific California Peruvian Westwind AtlanticNorth trade wind South Trade wind Gulf Stream Brazilian North Atlantic Labrador Canary Benguela Westwind IndianSouth Equatorial Monsoon Mozambique Somali Westwind Arctic Greenlandic
Let's summarize the research work What is called oceanic I succeeded the most ... For the lesson I ... I did not know ... - Now I know ...). I realized that... It was difficult... with the flow? What causes currents? What is the main cause of currents? What is the regularity of the distribution of currents over the surface the globe? What are the types of currents? Why study ocean currents?
1. The current is…… 2. The main reason for the formation of currents is…… Cold current is indicated by the arrow of …….. colors, and warm current is ………. 4. A cold stream has a water temperature of ……… than that of the surrounding water stream. 5. Here are some ocean currents a) Warm: b) Cold: A navigator's report Restore the corrupted text
Check Your Work 1. Current is the movement of water in the ocean or sea in a horizontal direction. 2. The main reason for the formation of currents is the wind. 3. Cold current is indicated by an arrow of blue color, and warm - red. 4. A cold stream has a lower water temperature than the surrounding water stream. 5. Here are some ocean currents a) Warm: b) Cold:
Homework 1. Study the materials of the paragraph Make a route for a sea voyage through the Indian Ocean using currents. Draw it on a contour map. 3. Complete task 5 at the end of paragraph 27.
This I know
2. What are the reasons for the formation of currents?
The main reason for the formation of currents is the wind. In addition, the movement of water is affected by the difference in its temperature, density, salinity.
3. What is the role of ocean currents?
Ocean currents influence climate formation. Currents redistribute heat on the Earth. Due to the currents, planktonic organisms carry out their movements.
4. What are the types of ocean currents and give examples of them?
Currents by origin are windy (the course of Western winds), tidal, density.
Temperature currents are warm (Gulf Stream) and cold (Bengal).
Currents in terms of stability are permanent (Peruvian) and seasonal (currents of the northern part of the Indian Ocean, El Niña)
5. Match the current - warm (cold):
1) the course of the Western winds
2) Gulf Stream
3) Peruvian
4) Californian
5) Kuroshio
6) Benguela
A) warm
B) cold
This I can
6. Give examples of the interaction of the ocean and the atmosphere.
Currents redistribute heat and influence air temperature and precipitation. Sometimes the interaction of currents and the atmosphere leads to the formation of adverse and dangerous weather phenomena.
7. Give a description of the course of the Western winds according to the plan:
1. Geographic location
The current bends between 400 and 500 S. Earth.
2. Type of flow
A) according to the properties of water (cold, warm)
The current is cold.
B) by origin
The course of the Western winds is windy in origin. It is caused by westerly winds in temperate latitudes.
C) stability (permanent, seasonal)
The flow is constant.
D) by location in the water column (surface, deep, bottom)
Surface flow.
8. In ancient times, not knowing the real reasons for the formation of currents in the Ocean, sailors believed that Neptune, the Roman god of the seas, could drag a ship into the ocean depths. Using information from popular science and fiction, Internet, collect materials about the ships, the disappearance of which is associated with currents. Document the materials in the form of drawings, essays, reports.
Secrets bermuda triangle
The Bermuda Triangle or Atlantis is a place where people disappear, ships and planes disappear, navigation instruments fail, and almost no one ever finds the crashed. This hostile, mystical, ominous country for a person instills such great horror in the hearts of people that they often simply refuse to talk about it.
About the existence of such a mysterious and amazing phenomenon called the Bermuda Triangle a hundred years ago, few people knew. To actively occupy people's minds and force them to put forward various hypotheses and theories, this mystery of the Bermuda Triangle began in the 70s. of the last century, when Charles Berlitz published a book in which he described the stories of the most mysterious and mystical disappearances in this region in an extremely interesting and fascinating way. After that, the journalists picked up the story, developed the theme, and the story of the Bermuda Triangle began. Everyone began to worry about the secrets of the Bermuda Triangle and the place where the Bermuda Triangle or the missing Atlantis is located.
This wonderful place or the missing Atlantis is located in the Atlantic Ocean near the coast North America- between Puerto Rico, Miami and Bermuda. It is located in two climatic zones at once: the upper part, the larger one - in the subtropics, the lower one - in the tropics. If these points are connected with each other by three lines, a large triangular figure will appear on the map, the total area of \u200b\u200bwhich is about 4 million square kilometers. This triangle is rather conditional, since ships also disappear outside its borders - and if you mark on the map all the coordinates of disappearances, flying and floating vehicles, you will most likely get a rhombus.
At knowledgeable people the fact that ships often crash here is not particularly surprising: this region is not easy to navigate - there are many shallows, a huge number of fast water and air currents, cyclones often arise and hurricanes rage.
Water currents. Gulfstream.
Almost the entire western part of the Bermuda Triangle is crossed by the Gulf Stream, so the air temperature here is usually 10 ° C higher than in the rest of this mysterious anomaly. Because of this, in the places of collisions of atmospheric fronts of different temperatures, one can often see fog, which often strikes the mind of overly impressionable travelers. The Gulf Stream itself is a very fast current, the speed of which often reaches ten kilometers per hour (it should be noted that many modern transoceanic ships move slightly faster - from 13 to 30 km / h). An extremely fast flow of water can easily slow down or increase the movement of the ship (it all depends on which direction it is sailing). There is nothing surprising in the fact that ships of weaker power in the old days easily went off course and were swept absolutely in the wrong direction, as a result of which they suffered wrecks and disappeared forever in the oceanic abyss.
In addition to the Gulf Stream, strong but irregular currents constantly arise in the Bermuda Triangle, the appearance or direction of which is almost never predictable. They are formed mainly under the influence of tidal and ebb waves in shallow water and their speed is as high as that of the Gulf Stream - and is about 10 km / h. As a result of their occurrence, whirlpools are often formed, causing trouble for small ships with a weak engine. There is nothing surprising in the fact that if in former times a sailing ship got here, it was not easy for him to get out of the whirlwind, and under especially unfavorable circumstances, one might even say - impossible.
In the east of the Bermuda Triangle, the Sargasso Sea is located - a sea without shores, surrounded on all sides instead of land by strong currents. Atlantic Ocean- Gulf Stream, North Atlantic, North Trade Wind and Canary.
Outwardly, it seems that its waters are motionless, the currents are weak and hardly noticeable, while the water here is constantly moving, because water streams, pouring into it from all sides, rotate the sea water clockwise. Another remarkable thing about the Sargasso Sea is the huge amount of algae in it (contrary to popular belief, there are also areas with completely clear water). When in former times ships were brought here for some reason, they got entangled in dense sea plants and, falling into a whirlpool, albeit slowly, they were no longer able to get back.
The movement of waters in the oceans is just beginning to be studied, even very little is known about surface currents, and deep and bottom currents have not yet been studied at all. Meanwhile, there is no doubt that the surface and deep-water movement of water in the oceans forms one complex system, which, even in its part, coinciding with the oceanic surface, has not been sufficiently studied. It is not surprising because this most complex oceanographic phenomenon, no less complex than similar movements in the air ocean, does not yet have a coherent theory covering all the causes that determine the movement of waters in the ocean.
The causes that can excite the movement of waters in the ocean and create the observed system of ocean currents can be divided into three groups. Causes of a cosmic nature, density difference and winds.
According to the modern view, cosmic causes, the rotation of the Earth and the tides, cannot excite anything like those observed in surface layers currents, and therefore these causes are not considered here.
The second group of causes that excite currents are all those conditions that produce a density difference in sea water, namely, an uneven distribution of temperature and salinity.
The third reason for the emergence of surface (and, therefore, partly underwater) currents is the wind.
Water density difference
The difference in density was recognized by many as the most important cause of ocean currents, this view became widespread especially after the oceanographic research of the Challenger expedition.
At this time, first Carpenter, and then Moya, suggested that the density difference is one of the main causes of currents. Recently, Scandinavian scientists: Nansen, Bjerknes, Sandström, Petterson, have again renewed their interest in the phenomenon of density difference as the cause of currents.
The difference in density in sea water is the result of the simultaneous action of many factors that always exist in nature and therefore continuously change the density of particles. sea water in different places.
Each change in water temperature is accompanied by a change in its density, and the lower the temperature, the greater the density. Evaporation and freezing also increase density, while precipitation decreases it. Since salinity on the surface depends on evaporation, precipitation and melting of ice - phenomena that occur continuously - the salinity on the surface is constantly changing, and with it the density.
The average annual density distribution map shows that this element is unevenly distributed over the ocean surface, and the section of the Atlantic Ocean along the meridian confirms that densities are unevenly distributed in the oceans and at depths. Lines of equal density (isopycnes) descend to the tropical belt in the depths of the ocean, and with distance from the equator they come to the surface.
All this indicates that if there were no other causes that excite currents in the ocean, but only an uneven distribution of densities, then the waters of the ocean would certainly begin to move; however, the system of currents that arose in this way, both in character and in speed, would be completely different from the one now observed, because other equally important causes that also excite currents would be absent.
For example, in the trade winds, a layer of water several meters thick evaporates, and about 2 m of this evaporated water falls in the calm equatorial strip. From here, freshened water (with the existing system of currents) is carried away to the east by the Equatorial countercurrent. The rest of the mass of water vapor is transferred by the antitrade wind to temperate zones, where it falls out. Thus there is a constant loss of water in the tropics, which must be compensated by inflows from temperate latitudes. However, this reason alone is not able to create the system of currents observed in the oceans.
In the same way, ice in the circumpolar and polar latitudes partly desalinates water, makes it lighter, partly cools it, increases its density and makes it sink down, thus causing cooling of the deep layers of the ocean, and therefore give impetus to the movement of surface waters from temperate latitudes to polar. However, this reason alone cannot create the entire existing complex system of currents.
Thus, there is no doubt that the difference in density, constantly maintained by many causes in the entire mass of the waters of the World Ocean, should contribute to the formation of water movement, both on the surface and at depths.
The Norwegian scientist V. Bjerknes outlined his views on the causes that can excite movement in any medium, whether liquid or gas. These reasons lie solely in the inhomogeneity of the medium itself, which is always observed in nature. Bjerknes' ideas are remarkable precisely because he analyzes motion in cases taken from nature, and not some ideal environment, completely homogeneous, as is usually done.
Since Bjerknes takes a non-homogeneous medium, his reasoning should be based on a detailed study of the distribution of densities in the medium under consideration. Knowing the distribution of densities gives an idea of internal structure medium, and the latter makes it possible to judge the nature of the motions of particles arising in it.
The essence of Bjerknes's idea of calculating current velocities based on the distribution of densities. Suppose that in any mass of water temperature and salinity are distributed quite uniformly, then the density will be the same everywhere, and, consequently, the chosen mass of water will be homogeneous. Under such conditions, at the same depths, the pressures will be the same and will depend only on the number of layers located above each layer (in the first approximation, with every 10 m of depth, the pressure increases by one atmosphere).
If in such a homogeneous medium we draw surfaces of equal pressure, or, as they are otherwise called, isobaric, then they will coincide with level surfaces.
If we now make a vertical section of this mass of water, then the isobaric surfaces will be depicted on it by a system of parallel and horizontal lines.
If, however, temperature and salinity are unevenly distributed in a chosen mass of water, then the density of water at the same depths, which does not depend on these conditions, will be different.
Instead of density, Bjerknes uses reciprocal values - specific volumes, and through places in the liquid where the latter are the same, conducts surfaces, which on a taken vertical section are depicted by curves, which he called isosteres.
Thus, on a vertical section, two systems of lines will be obtained, some will be straight, parallel to the isobar horizon, and others - isosteres - will intersect them at different angles. The more the equilibrium in the liquid is disturbed, i.e., the further it is from homogeneity, the more the density, and consequently the specific volumes, will be more different at the same depths. Therefore, where the liquid is more homogeneous, and isosteres will be close to isobars; where, at close distances along the horizontal surface of the isobars, there are significant differences in the uniformity of the structure of the liquid, there the isosteres will rise or fall steeply.
Wind influence
The connection between wind and surface currents is so simple and easy to see that among sailors the wind has long been recognized as an important cause of currents.
The first who pointed out in science to the wind as the main cause of currents was W. Franklin in his discussions on the causes of the Gulf Stream (1770). Then A. Humboldt (1816), expounding his view on the causes of currents, pointed to the wind as their first cause. The paramount importance of the wind as the cause of currents has thus long been recognized by many, but it received strong support after mathematical processing question produced by Zoeppritz (1878).
Zoeppritz analyzed the question of the gradual transfer of motion from the surface layer of water, set in motion by the wind, to the next, from the last to the one lying under it, etc. Zoeppritz showed that in the case of an infinitely long time of action of the driving force of the wind, the motion will be transmitted, in depth in such a way that the velocities in the layers will decrease in proportion to the depths, regardless of the value internal friction. If the forces act for a limited time, and the entire system of moving particles has not come to a stationary state, then the velocities at different depths will depend on the magnitude of friction. Zoeppritz borrowed the coefficient of friction for his hypothesis from experiments on the outflow of liquids, including sea water, and inserted it into his formulas.
An objection was made to this theory, indicating that the amount of motion that exists in the trade winds is much less than the corresponding amount in the equatorial current. However, here we must take into account the duration and continuity of the trade winds; it is obvious that in this case, after the flow has reached a steady state, it only needs to make up for the loss of motion from internal friction, and therefore the wind in the aggregate over a long period of time can impart to the water the amount of motion that is observed in it and produce the existing flow.
Another more important objection indicates that the value of friction accepted in the theory does not at all correspond to the actual one, because when one layer of water moves over another, whirlpools must necessarily form, which absorb an enormous amount of energy. Consequently, the calculation of the magnitude and nature of the propagation of velocity with depth is constructed incorrectly.
Finally, the most important shortcoming of Zoeppritz's theory was noticed recently by Nansen, namely, it completely omits the influence of the deflection resulting from the rotation of the earth on its axis.
Zoeppritz's theory (dominated for about 30 years) drew attention to important features of the wind (drift) hypothesis of currents, and its main merit was that it first expressed the influence of the wind numerically, and, as always happens in such cases, the shortcomings of the hypothesis served as a source for further study, resulting in a new, more advanced wind theory, belonging to the Swedish scientist V. Ekman, which takes into account the evasive force from the rotation of the Earth on its axis.
If we assume the ocean is boundless and of infinite depth, and the wind over it acts continuously, for such a long time that a stationary state has been established in the water set in motion, then under these conditions the following conclusions are obtained.
First of all, it must be pointed out that the surface layer of water is set in motion by the wind due to two reasons: firstly, friction, and secondly, pressure on the windward sides of the waves, because the wind causes not only current, but also excitement. Both of these causes can be collectively called tangential friction.
According to Ekman's wind (drift) theory, the motion from the surface layer is transmitted down from layer to layer, decreasing in geometric progression. In this case, the direction of the surface current deviates from the direction of the wind that produces it by 45 ° for all latitudes equally.
The influence of the deflecting force from the rotation of the Earth on the axis affects not only the deviation of the current on the surface from the wind by 45°, but also in the further continuous turn of the direction of the current when the motion is transferred to the depth from layer to layer. Thus, with the transfer of the current from the surface to the depth, not only does the speed decrease rapidly (in a geometric progression), but the direction of the current constantly turns to the right in the northern hemisphere, and to the left in the southern hemisphere.
In the mouths of rivers flowing into the sea, the same phenomena are observed. River water, being lighter than sea water, forms even when mixed with sea water a lighter layer that has a certain movement away from the coast. The mass of such a surface current is also greater than the mass of one river water (according to the just remark of Admiral S. O. Makarov), due to the mixing of river water with sea water. The current formed in this way sucks in the colder water in the sea or ocean from the lower layers and causes a decrease in temperature in the near-surface layers at such depths where the temperature is much higher at some distance from the confluence of the river. Such a phenomenon was observed by Ekman near Gothenburg in Kattegat.
Exactly the same effect of the river current on the rise of more saline and denser deep water to the layers closer to the surface was observed by S.O. east winds, increasing the speed of the current of the surface fresh water from the river Neva and consequently reducing the thickness of the surface layer.
Influence of atmospheric pressure
In the seas, a similar influence of atmospheric pressure on their various parts affects significantly the currents in the straits connecting them with the oceans or other seas. For example, the Gulf Stream, at its beginning in the Strait of Florida, happens to have a greater speed with northerly, i.e. opposite, winds and less with southerly, favorable ones. This discrepancy is explained by the influence of atmospheric pressure; when northerly winds blow over the Gulf Stream in the Strait of Florida, then there is a slight atmospheric pressure over the Gulf of Mexico, causing the level in the bay to rise, the slope towards the Strait of Florida increases, and this in turn accelerates the outflow of water from the bay through the Strait of Florida to the north. Southerly winds occur in the Strait of Florida under the condition that there is high pressure over the Gulf of Mexico, which is why then the level in the bay decreases and the slope of the level in the Strait of Florida becomes smaller, and, consequently, the speed of the current decreases, despite the tailwinds.
Overview of all the above causes of currents
The above causes that excite the movement of water in the ocean are reduced to three conditions: the influence of atmospheric pressure differences, the influence of sea water density differences, and the influence of wind. The influence of the Earth's rotation on the axis and the influence of the shores can only modify the nature of already existing currents, but the last two circumstances by themselves cannot excite any movements of water.
The influence of atmospheric pressure differences cannot excite any significant currents. The following two causes remain: differences in the densities of sea water and wind.
Differences in density in the ocean always exist, and therefore always tend to set the particles of water in motion. In this case, the density differences act not only in the horizontal direction, but also in the vertical direction, exciting convection currents.
The wind, according to modern views, not only causes the emergence of surface currents, but also causes the origin of currents at different depths to the very bottom. Thus the significance of the wind as the causative agent of currents has recently been expanded and become more general.
The material available to oceanography on the distribution of densities in different places and at different depths in the oceans is still very small and not accurate enough; but on the basis of it it is already possible to make an attempt to determine numerically (according to the method of Bjerknes) those current velocities which the density difference can excite in the surface layers of the oceans.
Based on the meridional section through the North Equatorial Current of the Atlantic Ocean, it was determined that the existing between 10 and 20 ° N. sh. the density difference could produce a current of 5-6 nautical miles in 24 hours. Meanwhile, the average daily velocity of the Equatorial current observed in this place is about 15-17 nautical miles. If we calculate the speed of the same Equatorial current, corresponding only to the influence of the wind (assuming the NE trade wind speed of 6.5 m per second), then we get a daily current speed of 11 nautical miles. Adding this value to 5-6 nautical miles of daily velocity due to the difference in density, we get the observed 16-17 nautical miles per day.
The example given shows that the wind appears to be a more important cause of the excitation of currents on the "surface of the ocean" than the density difference.
A similar example for the Baltic Sea is even more convincing, it shows that even where the density differences are very large at short distances, the influence of the wind is still more important for the emergence of currents (see p. 273, currents of the Baltic Sea).
Finally, the very existence of a change in monsoon currents, as well as some movement and change in the currents of the tropical strip in all oceans in the winter and summer of the same hemisphere, is shown once again great importance winds for the existing system of currents. The movement of the meteorological equator with the seasons, of course, affects the distribution of water temperature (see the chapter on temperature), and hence the distribution of water density, but these changes are very small; the changes in the system of winds caused by the movement of the meteorological equator are very significant.
Thus, of these three causes of currents, it must be recognized that the wind is one of the most important. Many circumstances point to this; there is no doubt that if the wind did not exist, then the systems of currents that arose in the oceans would differ very significantly from the existing ones.
Here it will be appropriate to point out that in the ocean there are many currents with waters of completely different densities running side by side, and, despite the fact that between them, however, no exchange of water is formed at all.
Finally, all currents go along the bed formed by the waters of the ocean, which always have completely different physical properties than the waters of the currents themselves; however, even under these conditions, the currents continue to exist and move, without immediately mixing their waters with neighboring ones. Of course, such a mixing of their waters occurs, but it occurs very slowly and is largely due to the formation of whirlpools during the movement of one layer of water over another.
Which moves with a certain cyclicity and frequency. Differs in a constancy of physical and chemical properties and a specific geographical location. It can be cold or warm, depending on belonging to the hemispheres. Each such flow is characterized by increased density and pressure. Flow is being measured water masses in sverdrupy, in a broader sense - in units of volume.
Varieties of currents
First of all, cyclically directed water flows are characterized by such features as stability, speed, depth and width, Chemical properties, acting forces, etc. Based on international classification, flows are of three categories:
1. Gradient. Occur when exposed to isobaric layers of water. A gradient ocean current is a flow characterized by horizontal movements of the isopotential surfaces of the water area. According to their initial features, they are divided into density, baric, stock, compensation and seiche. As a result of the runoff flow, precipitation and ice melting are formed.
2. Wind. Determined by the slope of the sea level, the strength of the air flow and fluctuations in mass density. A subspecies is drifting. This is a flow of water caused purely by the action of the wind. Only the surface of the pool is exposed to oscillations.
3. Tidal. They appear most strongly in shallow water, in estuaries and near the coast.
A separate type of flow is inertial. It is caused by the action of several forces at once. According to the variability of movement, constant, periodic, monsoon and trade wind flows are distinguished. The last two are determined by direction and speed seasonally.
Causes of ocean currents
At the moment, the circulation of waters in the world's waters is only beginning to be studied in detail. By and large, specific information is known only about surface and shallow currents. The main snag is that the oceanographic system has no clear boundaries and is in constant motion. It is a complex network of flows due to various physical and chemical factors.
Nevertheless, the following causes of ocean currents are known today:
1. Cosmic impact. This is the most interesting and at the same time difficult to learn process. AT this case the flow is determined by the rotation of the Earth, the impact on the atmosphere and hydrological system of the planet of cosmic bodies, etc. A striking example is the tides.
2. Wind exposure. The circulation of water depends on the strength and direction air masses. In rare cases, we can talk about deep currents.
3. Density difference. Streams are formed due to uneven distribution of salinity and temperature of water masses.
atmospheric effect
In the world's waters, this kind of influence is caused by the pressure of heterogeneous masses. Coupled with cosmic anomalies, water flows in the oceans and smaller basins change not only their direction, but also their power. This is especially noticeable in the seas and straits. A prime example is the Gulf Stream. At the beginning of his journey, he is characterized by increased speed.
During the Gulf Stream, it is accelerated simultaneously by opposite and fair winds. This phenomenon forms a cyclic pressure on the layers of the pool, accelerating the flow. From here, in a certain period of time, there is a significant outflow and inflow of a large amount of water. The lower the atmospheric pressure, the higher the tide.
When the water level drops, the slope of the Florida Strait becomes less. Because of this, the flow rate is significantly reduced. Thus, it can be concluded that increased pressure reduces the force of the flow.
wind impact
The connection between the flows of air and water is so strong and at the same time simple that it is hard not to notice even with the naked eye. Since ancient times, navigators have been able to calculate the appropriate ocean current. This became possible thanks to the work of the scientist W. Franklin on the Gulf Stream, dating back to the 18th century. A few decades later, A. Humboldt indicated precisely the wind in the list of the main extraneous forces affecting the water masses.
From a mathematical point of view, the theory was substantiated by the physicist Zeppritz in 1878. He proved that in the World Ocean there is a constant transfer of the surface layer of water to deeper levels. In this case, the wind becomes the main influencing force on the movement. The current velocity in this case decreases in proportion to the depth. The determining condition for the constant circulation of waters is an infinitely long time of action of the wind. The only exceptions are the trade winds of air, which cause the movement of water masses in the equatorial strip of the World Ocean seasonally.
Density difference
The impact of this factor on water circulation is the most important cause of currents in the World Ocean. Large-scale studies of the theory were cited international expedition challenger. Subsequently, the work of scientists was confirmed by Scandinavian physicists.
The heterogeneity of the densities of water masses is the result of several factors at once. They have always existed in nature, representing a continuous hydrological system of the planet. Any deviation in water temperature entails a change in its density. In this case, an inversely proportional relationship is always observed. The higher the temperature, the lower the density.
Also, the difference in physical indicators is affected by state of aggregation water. Freezing or evaporation increases density, precipitation decreases it. Affects the strength of the current and salinity of water masses. It depends on the melting of ice, precipitation and the level of evaporation. In terms of density, the World Ocean is quite uneven. This applies to both surface and deep layers of the water area.
Currents of the Pacific Ocean
The general scheme of flows is determined by the circulation of the atmosphere. Thus, the east trade wind contributes to the formation of the North Current. It crosses the waters from the Philippine Islands to the coast Central America. It has two branches that feed the Indonesian Basin and the Equatorial Ocean Current Pacific Ocean.
The largest currents in the water area are the Kuroshio, Alaska and California currents. The first two are warm. The third stream is the cold ocean current of the Pacific Ocean. Swimming pool southern hemisphere form the Australian and Tradewind currents. A little to the east of the center of the water area, the Equatorial countercurrent is observed. Off the coast of South America, there is a branch of the cold Peruvian current.
AT summer time The El Niño ocean current operates near the equator. It pushes back the cold masses of water of the Peruvian Stream, forming a favorable climate.
Indian Ocean and its currents
The northern part of the basin is characterized by a seasonal change of warm and cold flows. This constant dynamics is caused by the action of the monsoon circulation.
AT winter period dominated by the Southwest Current, which originates in the Bay of Bengal. A little further south is Western. This ocean current of the Indian Ocean crosses the water area from the coast of Africa to the Nicobar Islands.
In summer, the east monsoon contributes to a significant change in surface waters. The equatorial countercurrent shifts to a depth and noticeably loses its strength. As a result, its place is occupied by powerful warm Somali and Madagascar currents.
Arctic ocean circulation
The main reason for the development of the undercurrent in this part of the World Ocean is a powerful influx of water masses from the Atlantic. The fact is that the centuries-old cover of ice does not allow the atmosphere and cosmic bodies to influence the internal circulation.
The most important course of the water area Arctic Ocean considered the North Atlantic. It drives huge volumes of warm masses, preventing the water temperature from dropping to critical levels.
The Transarctic current is responsible for the direction of ice drift. Other major streams include the Yamal, Svalbard, North Cape and Norwegian currents, as well as a branch of the Gulf Stream.
currents of the atlantic basin
The salinity of the ocean is extremely high. The zonality of water circulation is the weakest among other basins.
Here the main ocean current is the Gulf Stream. Thanks to him, the average water temperature is kept at around +17 degrees. This warm ocean warms both hemispheres.
Also the most important streams of the basin are the Canary, Brazilian, Benguela and Tradewind currents.