Tasks research work: Objectives of the research paper: Objectives of the research paper: Objectives of the research paper: Explain the reasons for education ocean currents Explain the reasons for the formation of ocean currents Familiarize yourself with the direction of surface and deep ocean currents Familiarize yourself with the direction of surface and deep ocean currents Learn to distinguish between warm and cold currents by description and on a map Learn to distinguish between warm and cold currents by description and on a map Name and show large ocean currents on a map currents Name and show major ocean currents on a map

Execute test tasks Complete test tasks. 1. Name the reason why tides are formed: t) attraction of the Ocean waters by the Moon; a) wind; d) earthquakes. 2. Does 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) waves are smaller;. 4. The reason for the formation of a tsunami: a) wind; i) attraction of the ocean waters 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 Bering Bay; i) Bengali; n) Gibraltar. 7. Of the listed seas, the saltiest is f) Mediterranean; i) Red; i) Baltic.

“My lesson plan and my successes” Last name, first name ________________________________________________ Testing Work in contour map Restoring 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 2 task - 1 point 3 task - 1 point 4 task - 2 points 5 task - 2 points 3 points – worked actively and independently in the lesson 2 points – worked independently in the lesson and helped a friend 1 point – completed all the tasks correctly and independently My successes? ? ? ? Maximum quantity points – 19 Evaluation criterion: “5” points “4” points My total points - My mark -

Ocean (sea) currents - movement of water in the ocean or sea in the 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: Reasons for the formation of currents in the ocean

The temperature of the current water is several degrees higher than the temperature of the surrounding water. The temperature of the current water is several degrees lower than the temperature of the surrounding water. Problematic question. The water temperature of the Peruvian Current off the coast of South America is 22 C o, and the North Atlantic Current is 2 C o. The first is considered cold, and the second is considered warm. Why?

Large ocean currents OceanWarm currentsCold currents PacificNorth Trade Wind South Trade Wind Kuroshio North Pacific California Peruvian Western winds AtlanticNorth Trade Wind South Trade Wind Gulf Stream Brazilian North Atlantic Labrador Canary Benguela West Winds IndianSouth Trade Wind Monsoon Mozambique Somali West Winds Arctic Arctic East Greenland

Let's summarize the results of the research work What is called oceanic? I succeeded most of all... During the lesson I... I didn’t know... - Now I know...). I realized that...It was difficult...with the current? For what reasons do currents arise? What is the main reason for the occurrence of currents? What is the pattern of distribution of currents on the surface of the globe? What types of currents are there? Why study ocean currents?

1. A current is…… 2. The main reason for the formation of currents is…… A cold current is indicated by an arrow of …….. color, and a warm one - ………. 4. A cold current has a water temperature ……… than that of the surrounding water flow. 5. Here are some ocean currents: a) Warm: b) Cold: A mariner’s report Restore the damaged text

Check your work 1. Current is the movement of water in an ocean or sea in a horizontal direction. 2. The main reason for the formation of currents is wind. 3. Cold current is indicated by an arrow blue, and warm - red. 4. A cold current has a lower water temperature than the surrounding water flow. 5. Here are some ocean currents: a) Warm: b) Cold:

Homework 1. Study the materials in the paragraph Make a route sea ​​travel across the Indian Ocean using currents. Draw it on a contour map. 3. Complete task 5 at the end of paragraph 27.

Which moves with a certain cyclicity and frequency. Characterized by consistency physical and chemical properties and specific geographic location. It can be cold or warm depending on the hemisphere. Each such flow is characterized by increased density and pressure. The consumption of water masses is measured in sverdrup, in a broader sense - in volume units.

Types of currents

First of all, cyclically directed water flows are characterized by such characteristics as stability, speed of movement, depth and width, chemical properties, influencing forces, etc. Based on international classification, currents come in three categories:

1. Gradient. Occur when exposed to isobaric layers of water. A gradient ocean current is a flow that is characterized by horizontal movements of isopotential surfaces of the water area. Based on their initial characteristics, they are divided into density, pressure, drain, compensation and seiche. As a result of the waste flow, sediments and ice melt occur.

2. Wind. They are determined by the slope of sea level, the strength of air flow and fluctuations in mass density. A subspecies is drift. This is a flow of water caused purely by the action of the wind. Only the surface of the pool is subject to vibrations.

3. Tidal. They appear most strongly in shallow waters, at river mouths and near the coast.

A separate type of flow is inertial. It is caused by the action of several forces at once. Based on 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

IN present moment Water circulation in the world's waters is just beginning to be studied in detail. By and large, specific information is known only about surface and shallow currents. The main problem is that the oceanographic system has no clear boundaries and is in constant motion. It is a complex network of flows caused by various physical and chemical factors.

Nevertheless, the following causes of ocean currents are known today:

1. Cosmic influence. This is the most interesting and at the same time difficult process to study. IN in this case the flow is determined by the rotation of the Earth, the impact of cosmic bodies on the atmosphere and hydrological system of the planet, etc. A striking example is the tides.

2. Exposure to wind. Water circulation depends on the strength and direction of air masses. In rare cases, we can talk about deep currents.

3. Density difference. Streams are formed due to the uneven distribution of salinity and temperature of water masses.

Atmospheric exposure

In the world's waters, this kind of influence is caused by the pressure of heterogeneous masses. Coupled with space 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 striking example is the Gulf Stream. At the beginning of its journey, it is characterized by increased speed.

The Gulf Stream is accelerated by both contrary and favorable winds. This phenomenon forms a cyclic pressure on the layers of the pool, accelerating the flow. From here, at a certain period of time, there is a significant outflow and inflow large quantity water. How weaker pressure atmosphere, the higher the tide.

As water levels drop, the slope of the Straits of Florida becomes smaller. Because of this, the flow speed is significantly reduced. Thus, we can conclude that high blood pressure reduces the flow force.

Exposure to wind

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, sailors have been able to calculate the appropriate ocean current. This became possible thanks to the work of scientist W. Franklin on the Gulf Stream, dating back to the 18th century. Several decades later, A. Humboldt indicated the wind in the list of the main extraneous forces affecting 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 main force influencing the movement is the wind. The flow speed in this case decreases in proportion to the depth. The determining condition for constant water circulation is the infinitely long duration of wind action. The only exceptions are trade wind air flows, which cause the movement of water masses in the equatorial zone 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 carried out by the international Challenger expedition. Subsequently, the scientists' work was confirmed by Scandinavian physicists.

The heterogeneity of water mass densities is the result of several factors. 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.

The difference in physical indicators is also affected by physical state water. Freezing or evaporation increases density, precipitation decreases it. Affects the strength of the current and the salinity of water masses. It depends on melting ice, precipitation and evaporation levels. In terms of density, the World Ocean is quite uneven. This applies to both surface and deep layers of the water area.

Pacific Currents

The general flow pattern is determined by atmospheric circulation. Thus, the eastern trade wind contributes to the formation of the Northern Current. It crosses the waters from the Philippine Islands to the coast of Central America. It has two branches that feed the Indonesian Basin and the Pacific Equatorial Ocean Current.

The largest currents in the water area are the Kuroshio, Alaska and California currents. The first two are warm. The third current is the cold ocean current of the Pacific Ocean. The basin of the Southern Hemisphere is formed by the Australian and Trade Wind currents. A little east of center Equatorial countercurrent is observed in the water area. Off the coast of South America there is a branch of the cold Peruvian Current.

IN summer time The El Niño ocean current operates near the equator. It pushes aside 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 in warm and cold flows. This constant dynamics is caused by the action of the monsoon circulation.

IN winter period dominated by the South-Western Current, which originates in the Bay of Bengal. A little further south is Western. This oceanic current of the Indian Ocean crosses the waters from the coast of Africa to the Nicobar Islands.

In summer, the east monsoon contributes to a significant change surface waters. The equatorial countercurrent shifts to depth and noticeably loses its strength. As a result, its place is taken by powerful warm Somali and Madagascar currents.

Circulation of the Arctic Ocean

The main reason for the development of the underwater current in this part of the World Ocean is the 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 current in the Arctic Ocean is the North Atlantic. It brings in 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 flows include the Yamal, Spitsbergen, North Cape and Norwegian currents, as well as a branch of the Gulf Stream.

Atlantic Basin Currents

The salinity of the ocean is extremely high. The zonality of water circulation is the weakest among other basins.

The main ocean current here is the Gulf Stream. Thanks to it, the average water temperature remains at +17 degrees. This oceanic warmth warms both hemispheres.

Also, the most important currents in the basin are the Canary, Brazilian, Benguela and Trade Wind currents.

Mariners learned about the presence of ocean currents almost as soon as they began to plow the waters of the World Ocean. True, the public paid attention to them only when, thanks to the movement of ocean waters, many great things were accomplished. geographical discoveries, for example, Christopher Columbus sailed to America thanks to the North Equatorial Current. After this, not only sailors, but also scientists began to pay attention to ocean currents. close attention and strive to explore them as best and deeply as possible.

Already in the second half of the 18th century. The sailors studied the Gulf Stream quite well and successfully applied the acquired knowledge in practice: from America to Great Britain they walked with the current, and in the opposite direction they kept a certain distance. This allowed them to stay two weeks ahead of ships whose captains were not familiar with the area.

Ocean or sea currents are large-scale movements of water masses in the World Ocean at speeds from 1 to 9 km/h. These streams do not move chaotically, but in a certain channel and direction, which is the main reason why they are sometimes called rivers of the oceans: the width of the largest currents can be several hundred kilometers, and the length can reach several thousand.

It has been established that water flows do not move straight, but deviate slightly to the side and are subject to the Coriolis force. In the Northern Hemisphere they almost always move clockwise, in the Southern Hemisphere it’s the other way around.. At the same time, currents located in tropical latitudes (they are called equatorial or trade winds) move mainly from east to west. The strongest currents were recorded along the eastern coasts of the continents.

Water flows do not circulate on their own, but are set in motion by a sufficient number of factors - wind, rotation of the planet around its axis, gravitational fields of the Earth and Moon, bottom topography, outlines of continents and islands, differences in temperature indicators of water, its density, depth in different places in the ocean and even its physical and chemical composition.

Of all types of water flows, the most pronounced are the surface currents of the World Ocean, the depth of which is often several hundred meters. Their occurrence was influenced by trade winds constantly moving in tropical latitudes in a west-east direction. These trade winds form the huge flows of the North and South Equatorial Currents near the equator. A smaller part of these flows returns to the east, forming a countercurrent (when the movement of water occurs in the opposite direction from the movement of air masses). Most of them, when colliding with continents and islands, turn to the north or south.

Warm and cold water currents

It must be taken into account that the concepts of “cold” or “warm” currents are conditional definitions. So, despite the fact that the temperature of the water flows of the Benguela Current, which flows along the Cape of Good Hope, is 20 ° C, it is considered cold. But the North Cape Current, which is one of the branches of the Gulf Stream, with temperatures from 4 to 6 ° C, is warm.

This happens because cold, warm and neutral currents got their names based on a comparison of the temperature of their water with the temperature of the surrounding ocean:

• If the temperature indicators of the water flow coincide with the temperature of the surrounding waters, such a flow is called neutral;
• If the temperature of the currents is lower than the surrounding water, they are called cold. They usually flow from high latitudes to low latitudes (for example, the Labrador Current), or from areas where, due to large river flows, ocean water has a reduced salinity of surface waters;
• If the temperature of the currents is warmer than the surrounding water, then they are called warm. They move from tropical to subpolar latitudes, for example, the Gulf Stream.

Main water flows

On at the moment Scientists have recorded about fifteen main ocean water flows in the Pacific, fourteen in the Atlantic, seven in the Indian and four in the Arctic Ocean.

It is interesting that all currents of the Arctic Ocean move at the same speed - 50 cm/sec, three of them, namely the West Greenland, West Spitsbergen and Norwegian, are warm, and only the East Greenland is a cold current.

But almost all oceanic currents of the Indian Ocean are warm or neutral, with the Monsoon, Somali, Western Australian and Cape Agulhas current (cold) moving at a speed of 70 cm/sec, the speed of the rest varies from 25 to 75 cm/sec. The water flows of this ocean are interesting because, together with the seasonal monsoon winds, which change their direction twice a year, the oceanic rivers also change their course: in winter they mainly flow to the west, in summer - to the east (a phenomenon characteristic only of the Indian Ocean ).

Since the Atlantic Ocean stretches from north to south, its currents also have a meridional direction. Water flows located in the north move clockwise, in the south - counterclockwise.

A striking example of the flow of the Atlantic Ocean is the Gulf Stream, which, starting in the Caribbean Sea, carries warm waters to the north, breaking up along the road into several side streams. When the waters of the Gulf Stream find themselves in the Barents Sea, they enter the Arctic Ocean, where they cool and turn south in the form of the cold Greenland Current, after which at some stage they deviate to the west and again join the Gulf Stream, forming a vicious circle.

The currents of the Pacific Ocean are mainly latitudinal and form two huge circles: northern and southern. Since the Pacific Ocean is extremely large, it is not surprising that its water flows have a significant impact on much of our planet.

For example, trade wind water currents transport warm waters from the western tropical coasts to the eastern ones, which is why the western part of the Pacific Ocean is much warmer in the tropical zone opposite side. But in the temperate latitudes of the Pacific Ocean, on the contrary, the temperature is higher in the east.

Deep Currents

Enough long time Scientists believed that deep ocean waters were almost motionless. But soon special underwater vehicles discovered both slow and fast-flowing water streams at great depths.

For example, under the Equatorial Current of the Pacific Ocean at a depth of about one hundred meters, scientists have identified the underwater Cromwell Current, moving eastward at a speed of 112 km/day.

A similar movement of water flows, but already in Atlantic Ocean, Soviet scientists found: the width of the Lomonosov Current is about 322 km, and the maximum speed of 90 km/day was recorded at a depth of about one hundred meters. After this, another underwater flow was discovered in Indian Ocean, however, its speed turned out to be much lower - about 45 km/day.

The discovery of these currents in the ocean gave rise to new theories and mysteries, the main one of which is the question of why they appeared, how they were formed, and whether the entire area of ​​the ocean is covered by currents or there is a point where the water is still.

The influence of the ocean on the life of the planet

The role of ocean currents in the life of our planet can hardly be overestimated, since the movement of water flows directly affects the planet’s climate, weather, and marine organisms. Many compare the ocean to a huge heat engine driven by solar energy. This machine creates a constant exchange of water between the surface and deep layers of the ocean, providing it with oxygen dissolved in the water and influencing the life of marine inhabitants.

This process can be traced, for example, by considering the Peruvian Current, which is located in Pacific Ocean. Thanks to the rise of deep waters, which lift phosphorus and nitrogen upward, animal and plant plankton successfully develop on the ocean surface, resulting in the organization food chain. Plankton is eaten by small fish, which, in turn, become prey to larger fish, birds, and marine mammals, which, given such food abundance, settle here, making the region one of the most highly productive areas of the World Ocean.

It also happens that a cold current becomes warm: average temperature environment rises by several degrees, causing warm tropical showers to fall on the ground, which, once in the ocean, kill fish accustomed to cold temperatures. The result is disastrous - a huge amount of dead small fish ends up in the ocean, large fish leave, fishing stops, birds leave their nesting places. As a result, the local population is deprived of fish, crops destroyed by heavy rains, and profits from the sale of guano (bird droppings) as fertilizer. It can often take several years to restore the previous ecosystem.

what is the main reason for the formation of surface ocean currents

Atmospheric circulation (wind system)

The main cause of surface currents in the open ocean is wind. Therefore, there is a close relationship between the directions and speeds of currents and prevailing winds. It is believed that the speed of ocean currents is about 10 times less than the speed of the wind that creates them.
In the tropical zone of the World Ocean, where stable trade winds of the north-eastern direction dominate in the northern hemisphere and south-eastern in the southern hemisphere, constant and powerful trade wind currents arise on both sides of the equator, which, under the influence of the deflecting force of the Earth's rotation (Coriolis force), acquire a latitudinal direction and cross the Pacific, Indian (except for its northern tropical part) and Atlantic oceans from east to west. In the northern hemisphere it is the Northern Trade Wind Current, in the southern hemisphere it is the Southern Trade Wind Current. Between these currents along the equator, an Equatorial countercurrent is formed, which, unlike trade winds, has a direction from west to east. Trade wind currents, encountering the eastern shores of the continents on their way, push up the waters (raise the level) and, under the influence of the configuration of the shores, turn to the right in the northern hemisphere and to the left in the southern hemisphere.

The world's oceans are an incredibly complex, multifaceted system that has not been fully studied to date. Water in large water basins should not be stationary, as this would quickly lead to a large-scale environmental disaster. One of the most important factors in maintaining balance on the planet is the currents of the World Ocean.

Reasons for the formation of currents

An ocean current is a periodic or, on the contrary, constant movement of impressive volumes of water. Very often, currents are compared to rivers, which exist according to their own laws. Water circulation, its temperature, power and flow speed - all these factors are determined by external influences.

The main characteristics of ocean currents are direction and speed.

The circulation of water flows in the World Ocean occurs under the influence of physical and chemical factors. These include:

• Wind. Under the influence of strong air currents, water moves on the surface of the ocean and at its shallow depths. The wind has no effect on deep-sea currents.
• Space. The influence of cosmic bodies (Sun, Moon), as well as the rotation of the Earth in orbit and around its axis leads to the displacement of layers of water in the World Ocean.
• Different indicators of water density- what determines the appearance of ocean currents.

Rice. 1. The formation of currents largely depends on the influence of space.

Direction of currents

Depending on the direction of water flows, they are divided into 2 types:

• Zonal- moving to the East or West.
• Meridional- directed to the North or South.

There are other types of currents, the appearance of which is caused by ebbs and flows. They are called tidal, and they are most powerful in the coastal zone.

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Sustainable are called currents in which the strength of the flow and its direction remain unchanged. These include the Southern Trade Wind and Northern Trade Wind Currents.

If the flow changes, then it is called unstable. This group includes all surface currents.

Our ancestors have known about the existence of currents since time immemorial. During shipwrecks, sailors threw corked bottles into the water with notes containing the coordinates of the incident, requests for help, or words of farewell. They knew for sure that sooner or later their messages would reach people precisely thanks to currents.

Warm and cold currents of the World Ocean

The formation and maintenance of climate on the globe is greatly influenced by ocean currents, which, depending on the temperature of the water, can be warm or cold.

Warm water flows are called water flows whose temperature is above 0. These include the Gulf Stream, Kuroshio, Alaskan and others. They usually move from low latitudes to high.

The most warm current in the World Ocean is El Niño, whose name translated from Spanish means the Christ Child. And this is not without reason, since a strong and full of surprises current appears on the globe on Christmas Eve.

Fig.2. El Niño is the warmest current.

Cold currents have a different direction of movement, the largest of which are the Peruvian and Californian.

The division of ocean currents into cold and warm is very arbitrary, since it shows the ratio of the temperature of the water in the flow to the temperature of the surrounding water. For example, if the water in the thickness of the current is warmer than in the surrounding water space, then such a flow is called thermal, and vice versa.. Total ratings received: 332.