Sometimes they say that it would be more correct to call our planet not Earth, but Water, because land (“earth” as such) is only a quarter of its surface. The rest of the space belongs to the oceans that make up the world's oceans. It is in it, as scientists suggest, that life once originated... and to this day, the ocean largely determines life on land. And this is not only about shipping, connecting cities and countries, fishing, which has fed many nations from time immemorial, not only about a pleasant holiday on the sea coasts... The “breath” of the ocean is felt by earth's atmosphere– it is this that largely determines the climate.
The world's oceans are located in constant movement. The flows of water in it - a kind of “rivers in the ocean” - are called currents. They can be permanent and periodic, underwater and surface, cold and warm, steady (not changing over time) and steady (changing).
The reasons that give rise to sea currents are very diverse. Eat tidal currents, especially strong near the coast, compensatory, associated with the slope of the sea level, wind, and constant winds, changing direction depending on the season, generate the same currents - monsoon and trade winds. Causes currents and difference in atmospheric pressure above the surface of the ocean.
Constant currents have different direction. Some of them start at low latitudes and move to high ones - they carry warm waters, others - on the contrary, are cold currents. Since the main "battery" solar energy on our planet it is an ocean, then it depends on how sea currents “carry” and “distribute” the heat different areas land, the weather on Earth largely depends, and since the currents are constant, so does the climate.
Some permanent currents have even received proper names– for example, the Gulf Stream. This is a warm current from Florida to Scandinavia, Barents Sea and Northern Arctic Ocean. The width of this current is from 70 to 90 km, and the depth extends almost to the bottom. This warm “river in the ocean” moves approximately 50 million cubic meters of water every second - that’s more than all the rivers on Earth combined! The world's most powerful ocean current carries warm waters from Gulf of Mexico to the north, transferring up to 100 kcal/cm2 of heat - approximately as much as the world's oceans as a whole receive from the Sun. It is thanks to him that the port of Murmansk does not freeze in winter - despite the fact that it is located beyond the Arctic Circle. It also softens the climate European countries adjacent to the Atlantic Ocean: in North America at the same latitude the climate is more severe. However, this is also the merit of another movement - Labrador. In itself it is cold, but when faced with warm Gulf Stream, it deflects it, directing it towards Europe.
However, cold currents also play an equally important role in creating climatic conditions. So, everyone knows that it’s hot in the tropics, but few people think that it could be even hotter there (maybe it would be impossible to live), if not for the cold Benguela Current off the southwestern coast of Africa and the same current Humboldt (aka Peruvian) off the west coast South America. It is they who have a “cooling” effect on the tropical region. At the same time, the influence of the Peruvian Current “dries” the climate of South America, forming deserts.
Sea currents affect not only air temperature, but also the movement of air masses, sometimes even provoking hurricanes.
As you can see, ocean currents are a real weather “factory”. If they change, the climate as a whole will change. And these changes are happening right before our eyes. So, this is not the first year that the winter has been covered with snow. Western Europe, not accustomed to this state of affairs. Scientists explain this by the fact that the Gulf Stream is slowing down and cooling. This is due to the process of global cooling... yes, exactly cooling. None global warming no – but the cold snap is already approaching three centuries, and clear evidence of this is the cooling of the Gulf Stream. Is this somehow related to human activity? Head of the department rational environmental management and Ecology of the Faculty of Geography of Moscow State University, Academician A. Kapitsa believes that to assume this is sheer megalomania: a person cannot seriously damage nature. Global cooling associated with the displacement of magnetic poles, earth's axis and changes in solar activity.
The circulation of the waters of the World Ocean determines the exchange of matter, heat and mechanical energy between the ocean and the atmosphere, surface and deep, tropical and polar waters. Sea currents transport large masses of water from one area to another, often quite remote areas. The currents break latitudinal zonation in temperature distribution. In all three oceans - the Atlantic, Indian and Pacific - temperature anomalies arise under the influence of currents: positive anomalies are associated with the transfer of warm waters from the equator to higher latitudes by currents close to meridional direction; negative anomalies are caused by oppositely directed (from high latitudes to the equator) cold currents. Negative temperature anomalies are intensifying, in addition, with the rise deep waters off the western coasts of the continents, caused by the movement of water by trade winds.[...]
The influence of currents affects not only the magnitude and distribution of average annual temperature values, but also its annual amplitudes. This is especially clearly manifested in areas of contact between warm and cold currents, where their boundaries shift throughout the year, such as, for example, in the Atlantic Ocean in the area of contact of the Gulf Stream and Labrador Currents, in the Pacific Ocean in the area of contact of the Kuroshio and Kuril (Oyashio) currents. .[...]
Currents influence the distribution of other oceanological characteristics: salinity, oxygen content, nutrients, color, transparency, etc. The distribution of these characteristics has a huge impact on the development biological processes, vegetable and animal world seas and oceans. Variability of sea currents in time and space, their displacement frontal zones influence biological productivity oceans and seas.[...]
Big influence currents influence the Earth's climate. For example, in tropical areas Where eastern transport predominates, significant cloudiness, precipitation, and humidity are observed on the western shores of the oceans, while on the eastern shores, where winds blow from the continents, there is a relatively dry climate. Currents significantly influence pressure distribution and atmospheric circulation. Above the axes of warm currents, such as the Gulf Stream, North Atlantic, Kuroshio, North Pacific, a series of cyclones move, which determine weather coastal areas continents. The warm North Atlantic Current favors the strengthening of the Icelandic low pressure, and consequently, intense cyclonic activity in the North Atlantic, North and Baltic seas. The influence of Kuroshio on the area of the Aleutian low pressure in the northeastern region is similar Pacific Ocean.[ ...]
In areas where warm and cold currents meet, fog and overcast are often observed.[...]
Where warm currents penetrate deeply into temperate and subpolar latitudes, their influence on the climate is especially pronounced. The moderating influence of the Gulf Stream, the North Atlantic Current and its branches on the climate of Europe, and the Kuroshio Current on climatic conditions northern part of the Pacific Ocean. It should be noted that the North Atlantic Current is more important in this regard than Kuroshio, since the North Atlantic Current penetrates almost 40° north of Kuroshio.[...]
Sharp differences in climate are created when the shores of continents or oceans are washed by cold and warm currents. For example, the eastern coast of Canada is under the influence of the cold Labrador Current, while the western coast of Europe is washed by warm waters North Atlantic Current. As a result, in the zone between 55 and 70° N. w. The duration of the frost-free period on the Canadian coast is less than 60 days, on the European coast - 150-210 days. A striking example The influence of currents on climatic and weather conditions is the Chilean-Peruvian cold current, the water temperature of which is 8-10° lower than the surrounding waters of the Pacific Ocean. Above the cold waters of this current air masses, cooling, form a continuous cover of stratocumulus clouds, as a result, continuous cloudiness and absence of precipitation are observed on the coasts of Chile and Peru. The southeast trade wind creates a surge in this area, i.e. a departure from the coast surface waters and the rise of cold deep waters. When the coast of Peru is only under the influence of this cold current, this period is characterized by the absence of tropical storms, rains and thunderstorms, and in the summer, especially when the oncoming warm coastal current intensifies El Niño currents, tropical storms are observed here, destructive force thunderstorms, downpours that erode the soil, residential buildings, dams, embankments.
90, Influence ocean currents to the nature of coastal areas
In the oceans and seas, huge streams of water tens and hundreds of kilometers wide and several hundred meters deep move in certain directions over distances of thousands of kilometers. Such flows - “rivers of the oceans” - are called sea currents. They move at a speed of 1-3 km/h, sometimes up to 9 km/h. There are several reasons that cause currents: for example, heating and cooling of the water surface, precipitation and evaporation, differences in water density, but the most significant in the formation of currents is the role of wind.
Currents, according to their prevailing direction, are divided into zonal, flowing to the west and east, and meridional, carrying their waters to the north or south.
A separate group includes currents that move towards neighboring ones, which are more powerful and extended. Such flows are called countercurrents. Those currents that change their strength from season to season depending on the direction of coastal winds are called monsoon currents.
Among the meridional currents, the Gulf Stream is the most famous. It transports on average about 75 million tons of water every second. For comparison, we can point out that the deepest river in the world, the Amazon, carries only 220 thousand tons of water every second. The Gulf Stream transports tropical waters to temperate latitudes, largely determining the climate, and therefore the life of Europe. It was thanks to this current that Europe received a soft, warm climate and became the promised land for civilization, despite its northern location. Approaching Europe, the Gulf Stream is no longer the same stream that escapes from the Gulf of Mexico. Therefore, the northern continuation of the current is called the North Atlantic. The blue waters of the Gulf Stream are replaced by more and more green ones. Of the zonal currents, the most powerful is the current of the Western Winds. In the vast expanse of the Southern Hemisphere off the coast of Antarctica there are no significant land masses. Strong and steady westerly winds prevail over this entire area. They intensively transport ocean waters eastward, creating the most powerful Western Wind current in the entire World Ocean. It connects the waters of three oceans in its circular flow and transports about 200 million tons of water every second (almost 3 times more than the Gulf Stream). The speed of this current is low: to bypass Antarctica, its waters need 16 years. The width of the flow of the Western winds is about 1300 km.
Depending on the water temperature, currents can be warm, cold or neutral. The water of the former is warmer than the water in the region of the ocean through which they pass; the latter, on the contrary, are colder than the water surrounding them; still others do not differ from the temperature of the waters through which they flow. As a rule, currents moving away from the equator are warm; Currents going towards the equator are cold. They are usually less salty than warm. This is explained by the fact that they flow from areas with big amount precipitation and less evaporation or from areas where the water is desalinated by melting ice. Cold currents in the tropical parts of the oceans are formed due to the rise of cold deep waters.
An important regularity of currents in the open ocean is that their direction does not coincide with the direction of the wind. It deviates to the right in the Northern Hemisphere and to the left in Southern Hemisphere from the wind direction at an angle of up to 45°. Observations show that in real conditions the deviation at all latitudes is slightly less than 45°. Each underlying layer continues to deviate to the right (left) from the direction of movement of the overlying layer. At the same time, the flow speed decreases. Numerous measurements have shown that the currents end at depths not exceeding 300 meters. The significance of ocean currents lies primarily in the redistribution of solar heat on the Earth: warm currents contribute to an increase in temperature, and cold currents lower it. Currents have a huge impact on the distribution of precipitation on land. Territories washed by warm waters always have humid climate, and cold ones are dry; in the latter case, there is no rain, only fogs have a moisturizing value. Living organisms are also transported with currents. This primarily applies to plankton, followed by large animals. When warm currents meet cold ones, upward currents of water are formed. They raise deep water rich in nutritious salts. This water favors the development of plankton, fish and marine animals. Such places are important fishing grounds.
Sea currents have a significant impact on the climate of the coastal parts of the continents. In both hemispheres, between the equator and the 40th parallel, the eastern shores of the continent are warmer than the western ones. In the temperate zone, the relationship is the opposite: the eastern shores of the continent are colder than the western ones. In Western European countries, winters are mild, and in areas North America located in the same latitudes are harsh. The contrast between the relatively mild climate of Scandinavia and the climate of Greenland, covered with a thick layer of ice, is especially noticeable.
WEATHER LORD
The atmosphere and the ocean are in close, continuous interaction. Sun rays, falling on the surface of the ocean, heat the water, and the ocean accumulates huge reserves of thermal energy, especially in tropical waters, where the sun's rays fall almost vertically. The surface of the ocean transfers its heat to the air and saturates it with water vapor, which rises upward in the process of evaporation of the surface layers of water. The vapor contained in the air has a significant supply of potential energy in the form of latent heat, which is released when the vapor condenses in the clouds. Ocean energy creates winds, which carry away new heat flows from the surface of the sea, generating new winds.
Weather and climate are a manifestation of the nature around us and are largely influenced by the ocean.
The impact of the oceans on weather and climate depends on physical features the huge mass of water located in its basins.
The most important property of the ocean is its ability to absorb and emit heat, and sea water has a high heat capacity - the ability to accumulate heat. She absorbs great amount solar energy, and a ten-meter layer of ocean water accumulates more heat than the entire atmosphere. The sun's rays heat the surfaces of sea and land with equal intensity, but water, having a large heat capacity, absorbs much more heat at a relatively stable temperature, while at the same time the temperature of land increases greatly. After sunset, the temperature of the land drops quickly, and the sea cools slowly.
The earth's crust, being a solid dense substance, accumulates heat only in the upper layers, and the sea, which is in continuous movement, moves the upper warm and lower, colder layers and distributes heat to large areas due to currents. The storage capacity of the ocean increases the evaporation of water from the surface, absorbing huge amounts of heat.
Accumulating and reliably retaining heat, the ocean controls the planet's climate, highlighting two main zones: continental and maritime. Marine climate is characteristic of all land areas washed by seas, continental - for deep land masses. A typical example maritime climate can be considered the climate of the British Isles: even temperatures throughout the year, cool summers and mild winters, cloudy skies and rainy weather all year round. The central regions of Siberia have a continental climate: Cold winter and hot summers, droughts are replaced by thunderstorms. The central regions of Asia have sharply continental climate: they are rampant in winter very coldy, and in the summer, a cloudless sky and scorching sun turn everything around into a space languishing with heat and dust.
The influence of the sea on the temperature of different areas globe is the main cause of winds. Famous Indian Ocean monsoons are generated by seasonal fluctuations in the temperature of the ocean and the huge landmass lying to the north. During the hot summer, which is typical for this area of the planet, the land warms up much more than the ocean, which most solar energy accumulates. From highly heated land, the air also heats up, the density of which decreases, which creates a zone low blood pressure. More low temperature above the ocean, the air is compressed, contributing to an increase in pressure, and air masses rush from the sea to land - they are formed southwest monsoons, which blow from April to October. In winter, land cools faster than the ocean, and areas of high and low pressure change places, air masses rush from land to sea and are formed northeast monsoons, which blow from October to April. The location of the continents and oceans should have provided clear directions for the monsoons, but the rotation of the earth makes adjustments to the direction of the winds.
Cold and warm ocean currents also influence the climate of the planet, especially its coastal regions. Climate of coastal countries North Atlantic is largely determined by three currents - Gulf Stream, Labrador and East Greenland. The warm Gulf Stream originates in Gulf of Mexico and, escaping from there into the ocean through Straits of Florida, rushes in two powerful branches to the shores of Europe. Cold Labrador and East Greenland Currents head to the south, where, meeting the Gulf Stream, they lower its temperature to 5 - 8 ° C, which is greatly facilitated by cold northern winds. But still, the Gulf Stream brings a significant part of its warmth to the shores of Europe, determining the climate of this area. The entire European coast to the north Strait of Gibraltar is influenced by the Gulf Stream, which goes around Scandinavia and reaches Spitsbergen Islands, whose western coast is ice-free all year round, while Baltic Sea near Tallinn and Riga, located 30° to the south, is covered with solid ice in winter.
In mid-latitudes, where air masses move from west to east, the climate is influenced by the ocean and western winds simultaneously. Therefore, the climate of two cities - Japanese Yokohama and American San Francisco, lying at the same latitude on opposite sides of the Pacific Ocean, is very different from each other. In Yokohama annual fluctuations temperatures reach 28°C, and the climate has all the features of a continental one, while in San Francisco - 17°C and a maritime climate.
The ocean regulates precipitation over the continent. When there is a lack of moisture in the atmosphere, evaporation from the ocean surface increases, and moisture-saturated air masses move onto land, bringing with them rain and thunderstorms - powerful cyclones hover over the continents.
Vast expanses of ocean, in contact with the atmosphere, provide continuous gas exchange - the upper layers of the ocean are saturated with oxygen released when plankton photosynthesis, enrich the lower layers of the atmosphere with oxygen. That's why the ocean is called the "lungs" of the planet., therefore, a person is attracted to the sea coast, where it is always easy to breathe.
The ocean not only provides global influence on the Earth's climate, but also controls the weather in a small area. Due to the differences in the heat capacities of the sea and land, pleasant cool winds of the sea coasts - breezes - are born. During the day the sea breeze blows, then for a while everything calms down and the shore breeze begins to blow. Both of these winds are best observed when they are quiet. sunny weather, since their speed does not exceed 5 m/sec and when any other wind rises, they easily die out. Breeze - the same monsoon, only local scale with a daily cycle in changing direction.
Ocean currents redistribute what is absorbed solar heat in the horizontal direction and significantly influence the climate coastal areas they wash.
Yes, it's cold Bengal Current lowers the air temperature of the coastal part West Africa. In addition, it is not conducive to rainfall, because... cools the lower layers of air in the coastal part, and cold air, as is known, becomes heavier, denser, cannot rise, form clouds and give precipitation.
Warm currents ( Mozambique, Cape Agulhas Current), on the contrary, increase the air temperature by east coast continent, contribute to the saturation of the air with moisture and the formation of precipitation.
Warm East Australian Current, washing the coast of Australia, causes an abundance of precipitation on the eastern slopes Great Dividing Range.
Cold Peruvian Current , passing along the western coast of South America, greatly cools the air of coastal areas and does not contribute to precipitation. Therefore here is Atacama Desert, where rain is a rare occurrence.
The climate of both Europe and North America is greatly influenced by warm current Gulf Stream (North Atlantic). Scandinavian Peninsula lies at approximately the same latitudes as Greenland island. However, the latter is covered with a thick layer of snow and ice all year round, while coniferous and broad-leaved forests grow in the southern part of the Scandinavian Peninsula, washed by the North Atlantic Current.
Ebbs and flows
Periodic fluctuations in ocean (sea) level caused by the gravitational forces of the Moon and the Sun are tides And low tides.
Tidal currents in the World Ocean arise under the influence of gravitational forces (forces of attraction) of the Moon and the Sun. These are periodic fluctuations in water levels off the coasts of the open sea. The tidal force of the Moon is almost 2 times greater than the tidal force of the Sun. In the open sea, the tide is no more than 1 m, but upon entering narrowing bays the tidal wave rises; highest altitudes tides in the Bay of Fundy in southeastern Canada - 18 m. The frequency of tides can be semi-diurnal, diurnal or mixed.
The world's oceans have great value in people's lives. This is the source natural resources: biological(fish, seafood, pearls, etc.) and mineral(oil Gas). This is a transport space and a source of energy resources.
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