Ocean currents create particularly sharp differences in the temperature regime of the sea surface and themselves affect the distribution of air temperature and atmospheric circulation. Fortitude ocean currents leads to the fact that their influence on the atmosphere is of climatic importance. The crest of isotherms on average temperature maps clearly shows the warm influence of the Gulf Stream on the climate of the eastern North Atlantic and Western Europe.
Cold oceanic currents are also detected on average air temperature maps by corresponding perturbations in the configuration of isotherms - cold tongues directed to low latitudes.
Over areas of cold currents, the frequency of fog increases, in particular in Newfoundland, where air can move from the warm waters of the Gulf Stream to the cold waters of the Labrador Current. Over cold waters in the trade wind zone, convection is eliminated and cloudiness sharply decreases. This, in turn, is a factor that supports the existence of the so-called coastal deserts.
Influence of snow and vegetation cover on climate
Snow (ice) cover reduces soil heat loss and temperature fluctuations. The surface of the cover reflects solar radiation during the day and is cooled by radiation at night, so it reduces the temperature of the surface air layer. Spring to melt snow cover expended a large number of heat taken from the atmosphere. Thus, the air temperature above the melting snow cover remains close to zero. Over the snow cover, temperature inversions are observed: in winter - associated with radiative cooling, in spring - with snow melting. Above permanent snow cover polar regions even in summer there are inversions or isotherms. The melting of the snow cover enriches the soil with moisture and has great importance for the climatic regime of the warm season. A large snow cover albedo leads to an increase in scattered radiation and an increase in total radiation and illumination.
Dense grass cover reduces the daily amplitude of soil temperature and reduces it average temperature. It also reduces the daily amplitude of air temperature. A more complex influence on the climate has a forest, which can increase the amount of precipitation above it due to the roughness of the underlying surface.
However, the influence vegetation cover It has mainly microclimatic significance, which extends mainly to surface air layers and small areas.
General circulation of the atmosphere
The general circulation of the atmosphere is a system of large-scale air currents over globe, that is, such currents that are comparable in size to large parts of the continents and oceans. From general circulation The atmosphere is distinguished by local circulations, such as spray on the coasts of the seas, mountain-valley winds, glacial winds, etc. These local circulations are sometimes superimposed in certain areas on the general circulation of the atmosphere.
The daily synoptic weather maps show how the currents of the general circulation are distributed over large areas Earth or over the entire globe and how this distribution is constantly changing. The variety of manifestations of the general circulation of the atmosphere in particular depends on the fact that huge waves and vortices constantly arise in the atmosphere, which develop and move in different ways. This formation of atmospheric disturbances - cyclones and anticyclones - is the most characteristic feature general circulation of the atmosphere.
However, in the general circulation of the atmosphere, with all the variety of its continuous changes, one can also notice some constant features that are repeated every year. Such features are best detected by statistical averaging, in which the daily circulation disturbances are more or less smoothed out.
The average pressure value over each hemisphere decreases from the winter half of the year to the summer half of the year. From January to July, it decreases over the northern hemisphere by several mb; in the southern hemisphere, the opposite occurs. But atmospheric pressure is equal to the weight of a column of air, which means it is proportional to the mass of air. This means that from the hemisphere in which it is now summer, some air mass flows into the hemisphere in which it is currently winter. So there is a seasonal exchange of air between the hemispheres. For a year from northern hemisphere 1013 tons of air are transferred to the southern hemisphere and back.
We now turn to a more detailed consideration of the conditions of general circulation by zones.
The circulation of the waters of the World Ocean determines the exchange of the amount of matter, heat and mechanical energy between the ocean and the atmosphere, surface and deep, tropical and polar waters. Sea currents carry large masses of water from one area to another, often very remote areas. The currents are breaking latitudinal zonality in the temperature distribution. In all three oceans - the Atlantic, Indian and Pacific - under the influence of currents, temperature anomalies arise: positive anomalies are associated with the transfer of warm water from the equator to higher latitudes by currents that are close to meridional direction; negative anomalies are caused by oppositely directed (from high latitudes to the equator) cold currents. Negative temperature anomalies are intensified, in addition, by the rise of deep waters near the western coasts of the continents, caused by the water surges of the 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 the areas where warm and cold currents meet, where their boundaries shift during the year, such as, for example, in the Atlantic Ocean in the area where the Gulf Stream and Labrador currents meet, in the Pacific Ocean in the area where the Kuroshio and Kuril currents (Oyashio) meet. .
Currents also affect the distribution of other oceanological characteristics: salinity, oxygen content, nutrients, colors, 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 affect biological productivity oceans and seas.
Big influence exert currents on the Earth's climate. For example, in tropical areas, where the eastern transport predominates, significant cloudiness, precipitation, and humidity are observed on the western shores of the oceans, and on the eastern shores, where the winds blow from the continents, there is a relatively dry climate. Currents significantly affect the distribution of pressure and circulation of the atmosphere. Over axles warm currents such as the Gulf Stream, North Atlantic, Kuroshio, North Pacific, series of cyclones move that determine weather patterns coastal areas continents. The warm North Atlantic current favors the strengthening of the Icelandic low of pressure, and, consequently, intense cyclonic activity in the North Atlantic, the North and Baltic seas. Similarly, the influence of Kuroshio on the area of the Aleutian pressure minimum in the northeastern region Pacific Ocean. Warm currents penetrating high latitudes are associated with cyclonic circulation of the atmosphere, which contributes to the precipitation of abundant precipitation. On the contrary, spurs develop over cold currents. high pressure which causes a decrease in precipitation. In areas where warm and cold currents meet, fogs and overcast clouds are often observed.
Where warm currents penetrate deeply into temperate and subpolar latitudes, their influence on the climate is especially pronounced. The softening influence of the Gulf Stream, the North Atlantic Current and its branches on the climate of Europe, 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 respect than the Kuroshio, since the North Atlantic Current penetrates almost 40° north of the Kuroshio.
Sharp differences in climate are created if the shores of continents or oceans are washed by cold and warm currents. For example, the east coast of Canada is under the influence of the cold Labrador Current, while the western coast of Europe is washed by the warm waters of the North Atlantic Current. As a result, in the zone between 55 and 70 ° N. sh. the duration of the frost-free period on the coast of Canada is less than 60 days, on the European coast - 150-210 days. A prime 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. Over the cold waters of this current, the air masses, cooling, form a continuous cover of stratocumulus clouds, as a result, continuous cloudiness and no precipitation are observed on the coast of Chile and Peru. The southeast trade wind creates a surge in this area, i.e. moving away from the coast surface water 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 summer, especially when the warm coastal El Niño currents, tropical storms are observed here, destructive power thunderstorms, downpours that erode the soil, residential buildings, dams, embankments.
Pulsations of ocean currents, meandering and displacement of their axes to the south or north have a significant impact on the climate of coastal areas. Simultaneous observations of the temperature distribution within such large-scale streams as the Gulf Stream and Kuroshio revealed meanders (meanders) that have a wave-like character. They resemble the meanders of rivers and, in the form of a thickening of isotherms in the axis of the main stream, move along with the current. For example, the shift of the axis of Kuroshio to the south and north reaches 350 miles between 34 and 40 ° N. sh. The position of the fronts of the Kuroshio - Oyashio, Gulf Stream - Labrador and other currents experiences semi-monthly, monthly, semi-annual, annual and long-term fluctuations. As a result, fluctuations in climatological and meteorological factors on the coasts of adjacent continents. Weather Japan is associated with fluctuations in the Kuroshio front, climatic conditions Kuril ridge, about. Hokkaido and the north Honshu are influenced by the cold Oyashio Current.
1The article attempts to clarify the issue of the degree of influence of ocean surface currents on the climatic parameters of the adjacent land. The leading role of the ocean in the entire climate system of the Earth is determined. It is shown that the transfer of heat and moisture to land is carried out from the entire surface of the ocean. air masses. The role of surface ocean currents is to mix warm and cold water masses. It is noted that a significant role in the heat exchange between the ocean and the atmosphere is played by long-term Rossby waves, which are predominantly vertical water streams. It was revealed that ocean currents act locally on the adjacent land - only if the land area is very small and comparable to the size of the ocean current itself. In this case, depending on the ratio of the characteristics of the current itself and the adjacent land, small temperature changes(both up and down). It was not possible to establish a direct effect of currents on the amount of precipitation on land.
ocean surface currents
ocean-atmosphere interaction
climate system
Gulfstream
Rossby waves
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2. A. L. Bondarenko, E. V. Borisov, I. V. Serykh, G. V. Surkova, Yu. On the influence of the Rossby waves of the world ocean on the thermodynamics of its waters and atmosphere, weather and climate of the Earth // Meteorology and Hydrology. - 2011. - No. 4. - P. 75–81.
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AT last years Of great interest are questions related to changes in the characteristics of the Earth's climate system and their causes. It should be noted that systematic observations of climate change began relatively recently. Back in the 17th century, meteorology was part of the science of physics. It is to physicists that we owe the invention of meteorological instruments. So, Galileo and his students invented a thermometer, a rain gauge, a barometer. Instrumental observations began to be made in Tuscany only from the second half of the 17th century. At the same time, the first meteorological theories were developed. But it took almost two centuries on the way to systematic meteorological observations. They begin in the second half of the 19th century in Europe, after the invention of the telegraph. In the 1960s Was held big job to create global network weather observation systems. AT recent times increasingly in the media mass media there have been reports of increased cases of unusually heavy rainfall in Europe, sudden snowfall in the tropical regions of the United States, and North Africa, flowering plants in the Atacama desert. For a long time disputes continue about the degree of influence of the Gulf Stream on the climate of Europe, about the adverse consequences of the possible cessation of the functioning of this warm current. Unfortunately, the material is presented in such a way that it seems that the world has turned upside down and some catastrophic climatic events should be expected soon. The complex factual picture is fueled by various futuristic predictions about significant changes in the usual order of things, such as a significant rise in ocean levels, a significant change in the angle of the earth's axis, a strong increase in the temperature of the surface layer of the atmosphere.
In this regard, it is important to elucidate the reasons climatic events which should help to adequately perceive reality and take reasonable steps to adapt to the upcoming changes. This article attempts to determine the degree of influence of ocean surface currents on the climate of the adjacent land. This aspect was chosen due to the fact that in Earth science the influence of ocean currents on the climate of the adjacent land is slightly overestimated. Because of this, the role of the ocean in shaping the land climate is diminished, thereby distorting the understanding of the behavior of the Earth's climate system, and delaying the time for taking adequate adaptation measures.
There is an opinion that warm sea currents bring precipitation and heat to the adjacent land. This is taught in schools and universities. A comprehensive analysis of the existing picture shows the ambiguous manifestation of this postulate.
Ocean water can be considered as a store of solar heat on Earth. Ocean water absorbs 2/3 of solar radiation. The heat capacity of the ocean is so great that ocean water (except for the surface layer) practically does not change temperature seasonally (unlike the land surface). Therefore, it is warm on the ocean coast in winter, and cool in summer. If the area of land (compared to the area of the ocean) is small (as in Europe), then the warming effect of the ocean can spread over large areas. A close relationship has been found between ocean heat loss and atmospheric air warming, and vice versa, which is logical. At the same time, recent research data indicate a more complex picture of the thermal dynamics of the ocean and atmosphere. Scientists give the leading role in the loss of heat by the ocean to such a still little-studied phenomenon as the North Atlantic oscillation. These are periodic multi-decadal changes in ocean temperature observed in the North Atlantic. Since the late 1990s a wave of ocean warming was observed. As a result, many areas of the northern hemisphere experienced an unusually high number of hurricanes. Currently, there is a transition to a period of lowering the temperature of surface ocean waters. This will likely reduce the number of hurricanes in the northern hemisphere.
The seasonal constancy of the temperature of the entire mass of ocean water, especially in the tropics, led to the formation of permanent centers of high pressure above the ocean surface, which were called the centers of action of the atmosphere. Thanks to them, there is a general circulation of the atmosphere, which is a triggering mechanism for the general circulation of ocean waters. Through action constant winds surface currents in the oceans. With their help, the mixing of ocean water is carried out, namely: the flow of warm waters into cold regions (with the help of "warm" currents) and cool waters - into warm ones (with the help of "cold" currents). It must be remembered that these currents are “warm” or “cold” only in relation to the surrounding waters. For example, the temperature of the warm Norwegian current is + 3 °С, the cold Peruvian current is + 22 °С. Systems of ocean currents coincide with systems of constant winds and represent closed rings. As for the Gulf Stream, it really brings heat to the waters of the North Atlantic (but not to Europe). In its turn, warm waters The North Atlantic transmit their warmth atmospheric air, which, together with the western transfer, can spread to Europe.
Recent studies on the issue of heat transfer between the ocean waters of the North Atlantic and the atmosphere have shown that the leading role in changing the temperature of ocean waters is played not so much by currents as by Rossby waves.
Thermal interaction between the ocean and the atmosphere occurs when the temperature difference between the surface layer of ocean water and the lower air layer of the atmosphere. If the surface water temperature of the ocean more temperature lower atmosphere, the heat from the ocean is transferred to the atmosphere. Conversely, heat is transferred to the ocean if the air is warmer than the ocean. If the temperatures of the ocean and atmosphere are equal, then there is no heat transfer between the ocean and the atmosphere. For there to be a heat flow between the ocean and the atmosphere, there must be mechanisms that change the temperature of the air or water in the ocean-atmosphere contact zone. From the side of the atmosphere, it can be wind; from the side of the ocean, these are the mechanisms of water movement in the vertical direction, ensuring the inflow of water with a temperature different from the temperature of the contact zone of the ocean and the atmosphere. Long-term Rossby waves are such vertical motions of water in the ocean. These waves differ from the wind waves known to us in many ways. First, they have great length(up to several hundred kilometers) and a lower height. Researchers usually judge their presence in the sea by changing the vector of currents of water particles. Secondly, these are long-term inertial waves, the lifetime of which reaches ten or more years. Such waves are classified as gradient-vortex waves, which owe their existence to gyroscopic forces and are determined by the law of conservation of a potential vortex.
In other words, the wind generates a flow, which in turn generates inertial waves. With regard to this movement of water, the term "wave" is conditional. Water particles perform predominantly rotational movements, both in the horizontal and vertical planes. As a result, either warm or cold water masses rise to the surface. One of the consequences of this phenomenon is the movement and curvature (meandering) of current systems.
Research results and discussion
Currents, as a special case of the manifestation of the properties of ocean waters, when certain factors concur, can have a significant impact on the meteorological indicators of coastal land. For example, the warm East Australian Current contributes to even greater moisture saturation of the ocean air, from which precipitation falls as it rises along the Great Dividing Range in eastern Australia. The warm Norwegian current melts arctic ice in the western part Barents Sea. As a result, the waters of the Murmansk port do not freeze in winter (whereas in Murmansk itself in winter the temperature drops below -20 °C). It also heats a narrow strip of the western coast of Norway (Fig. 1, a). Thanks to the warm Kuroshio current off the eastern shores Japanese islands winter temperatures are higher than in the western part (Fig. 1, b).
Rice. 1. Distribution average annual temperatures air in Norway (a) and Japan (b); in hail Celsius: red arrow indicates warm currents
Cold currents can also affect the meteorological characteristics of coastal land. Thus, cold currents in the tropics off the western shores South America, Africa and Australia (respectively - Peruvian, Benguela, Western Australian) deviate to the west, and even colder ones rise in their place deep waters. As a result, the lower layers of coastal air are cooled, temperature inversion(when the lower layers are colder than the upper ones) and the conditions for the formation of precipitation disappear. Therefore, one of the most lifeless deserts is located here - coastal (Atacama, Namib). Another example is the influence of the cold Kamchatka current off the eastern shores of Kamchatka. It additionally cools the coastal areas (especially in summer) of an elongated small peninsula, and, as a result, southern border tundra extends much south of the mid-latitude boundary.
At the same time, it should be noted that it is impossible to speak with a sufficient degree of certainty about the direct influence of warm ocean currents on the increase in the amount of precipitation of coastal land. Knowing the mechanism of precipitation formation, priority in their appearance should be given to the presence of mountainous areas on the coasts, along which the air rises, cools, moisture in the air condenses and precipitation forms. The presence of warm currents on the coast should be considered a coincidence or an additional stimulating factor, but in no way main reason precipitation formation. Where big mountains no (for example, in the east of South America and the Arabian coast of Southwest Asia), the presence of warm currents does not lead to an increase in precipitation (Fig. 2). And this is despite the fact that in these areas the wind blows from the ocean to the land, i.e. there are all conditions for the full manifestation of the influence of warm currents on the coast.
Rice. 2. Distribution annual amount precipitation in the east of South America (a) and the Arabian coast of Southwest Asia (b): warm currents are marked with a red arrow
As for the formation of precipitation itself, it is well known that they are formed when air rises up and then cools down. In this case, moisture condenses and precipitation is formed. Neither warm nor cold currents have a significant effect on air rise. There are three regions of the Earth in which there are ideal conditions for the formation of precipitation:
1) at the equator, where air masses are always ascending due to the existing system of atmospheric circulation;
2) on the windward slopes of mountains, where air rises up the slope;
3) in areas temperate zone, experiencing the influence of cyclones, where air currents are always ascending. On the world map of precipitation, you can see that it is in these areas of the earth that the amount of precipitation is greatest.
An important condition for the formation of precipitation is the favorable stratification of the atmosphere. So, on a number of islands located in the center of the oceans, especially in areas adjacent to subtropical anticyclones, it rains extremely rarely throughout the year, despite the fact that the moisture content of the air is quite high here, and moisture transfer here exists towards these islands. . Most often, this situation is observed in the area of the trade winds, where the ascending currents are weak and do not reach the level of condensation. The formation of a trade wind inversion is explained by the heating of air in the process of its lowering in the zone of subtropical anticyclones, followed by cooling lower layers from colder water surfaces.
conclusions
Thus, the influence of surface ocean currents on the climate of the adjacent land is local and manifests itself only when certain factors coincide. A favorable combination of factors is manifested in at least two types of regions of the Earth. First, in small areas comparable to the size of currents. Secondly, in areas with extreme (high or low) temperatures. In these cases, if the water is warmer, a narrow coastal strip of land will be heated (North Atlantic Current in Britain). If the water temperature of the current is lower - on the contrary, the narrow coastal strip of land will cool ( Peruvian Current off the west coast of South America). AT general case greatest influence the entire mass of ocean water exerts heat on land through the transfer of heat by circulating atmospheric currents.
In the same way, moisture enters the land - from the surface of the entire ocean through atmospheric flows. In this case, one additional condition must be met - in order for the air to give up the moisture received above the ocean, it must rise to the upper layers of the atmosphere in order to cool. Only then the moisture condenses and precipitation falls. Ocean currents play a very minor role in this process. Most of all ocean currents (cold in tropical latitudes) contribute to the deficit of precipitation. This is manifested during the passage of cold currents in the tropics off the western coasts of South America, Africa and Australia.
As for the regions lying in the depths of the continent, for example, the Central Black Earth regions of the Russian Plain, the character atmospheric circulation during the frost-free period of the year, it mainly determines the regime of anticyclonic, sunny weather, which is formed in the masses of continental temperate air. Marine air masses come to this territory mainly in a modified form, having lost a significant part of their main properties along the way.
Speaking about the influence of the Gulf Stream on the climate of Europe, we must keep in mind two important moments. Firstly, under the Gulf Stream in this case it is necessary to understand the entire system of warm North Atlantic currents, and not the Gulf Stream itself (it is North American and has nothing to do with Europe). Secondly, remember about the inflow of heat and moisture from the surface of the entire Atlantic Ocean through their transfer by air masses. One warm ocean current is clearly not enough to heat the whole of Europe.
In the end, it is necessary to recall that, being wind-driven, the surface currents of the World Ocean are unlikely to disappear as long as the system of atmospheric circulation that has been established on Earth exists.
Bibliographic link
Anichkina N.V., Rostom G.R. ON THE DEGREE OF INFLUENCE OF OCEAN SURFACE CURRENTS ON THE CLIMATE OF THE ADJACENT LAND // Uspekhi modern natural science. - 2016. - No. 12-1. - P. 122-126;URL: http://natural-sciences.ru/ru/article/view?id=36273 (Accessed: 03/29/2019). We bring to your attention the journals published by the publishing house "Academy of Natural History"
Ocean currents redistribute the absorbed solar heat in the horizontal direction and affect the climate coastal areas they border.
Yes, cold bengal current lowers the air temperature of the coastal part West Africa. In addition, it does not favor rainfall, because. cools the lower layers of air in the coastal part, and cold air, as you know, becomes heavier, denser, cannot rise, form clouds and give precipitation.
The warm currents Mozambique, for Cape Agulhas), on the contrary, increase the air temperature by east coast mainland, 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 rainfall is rare.
Great influence on the climate of both Europe and North America has a warm current Gulf Stream (North Atlantic). Scandinavian Peninsula lies at approximately the same latitudes as Greenland. However, the last all year round covered with a thick layer of snow and ice, while coniferous and broad-leaved forests grow in the southern part of the Scandinavian Peninsula, washed by the North Atlantic Current.
Ebb and flow
Periodic fluctuations in the level of the ocean (sea), caused by the forces of attraction of the Moon and the Sun, are tides and low tide.
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 the water level near the coasts in 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 at the entrance to the narrowing bays, the tidal wave rises; greatest heights tides in the Bay of Fundy in southeastern Canada - 18m. The frequency of tides can be semi-diurnal, diurnal or mixed.
The world ocean has 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.
90, Influence of ocean currents on 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 streams - "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 for causing currents: for example, heating and cooling of the water surface, precipitation and evaporation, differences in water density, but the role of wind is the most significant in the formation of currents.
Currents in the direction prevailing in them are divided into zonal, going to the west and east, and meridional - carrying their waters to the north or south.
In a separate group, currents are distinguished, going towards neighboring, more powerful and extended ones. Such flows are called countercurrents. Those currents that change their strength from season to season, depending on the direction of the coastal winds, are called monsoons.
Among the meridional currents, the most famous is the Gulf Stream. It carries on average about 75 million tons of water every second. For comparison, it can be pointed out that the Amazon, the most full-flowing river in the world, carries only 220 thousand tons of water every second. The Gulf Stream carries tropical waters to temperate latitudes, largely determining the climate, and hence the life of Europe. It is thanks to this current that Europe received a soft, warm climate and became the promised land for civilization, despite its northern position. Approaching Europe, the Gulf Stream is no longer the same stream that breaks out of the Gulf of Mexico. Therefore, the northern continuation of the current is called the North Atlantic. The blue waters of the Gulf Stream are changing more and more green. Of the zonal currents, the most powerful is the current Western winds. In the vast expanse of the Southern Hemisphere off the coast of Antarctica, there are no significant land masses. All this space is dominated by strong and steady westerly winds. They intensively carry the waters of the oceans in an easterly direction, creating the most powerful Western wind current in the entire World Ocean. It connects the waters of three oceans in its circular flow and carries about 200 million tons of water every second (almost 3 times more than the Gulf Stream). The speed of this current is small: to bypass Antarctica, its waters need 16 years. The width of the current of the Western winds is about 1300 km.
Depending on the temperature of the water, the currents can be warm, cold and neutral. The water of the former is warmer than the water in the region of the ocean through which they pass; the second, on the contrary, is colder than the water surrounding them; others do not differ from the temperature of the waters among which they flow. As a rule, currents moving away from the equator are warm; equator currents are cold. They are usually less salty than warm. This is because they flow from areas with large quantity rainfall and less evaporation, or from areas where the water is desalinated by melting ice. The cold currents of the tropical parts of the oceans are formed due to the rise of cold deep waters.
An important pattern 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 direction of the wind at an angle of up to 45°. Observations show that under real conditions the deviation at all latitudes is somewhat less than 45°. Each underlying layer continues to deviate to the right (left) from the direction of motion of the overlying layer. In this case, the flow rate decreases. Numerous measurements have shown that currents end at depths not exceeding 300 meters. The significance of ocean currents lies primarily in the redistribution of the Earth's solar heat: warm currents contribute to an increase in temperature, while cold ones 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 - dry; in the latter case, no rains fall, only mists have a moisturizing value. Living organisms are carried along with currents. This primarily applies to plankton, followed by large animals. When warm currents meet cold currents, ascending currents of water are formed. They raise deep water rich in nutrient 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 mainland are warmer than the western ones. In the temperate zone, the ratio is reversed: the eastern shores of the mainland are colder than the western ones. In the countries of Western Europe, winters are mild, and in areas of North America located at the same latitudes, they are severe. The contrast between the relatively mild climate of Scandinavia and the climate of Greenland, covered with a thick layer of ice, is especially noticeable.
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