Which ocean currents are warm

When it cools, the density increases. It sinks to greater depths and flows southward. The Atlantic current system transports enormous amounts of heat to the north through this thermohaline process and greatly exceeds the share transported by the wind-driven ocean circulation. By comparison, the share moved by the Indian Ocean is negligible. It is the only ocean basin that transports heat northward throughout its length, even in the southern hemisphere.

Europeans all benefit from the northward trend, thanks to the Gulf Stream and the North Atlantic Current. The climate in the region of the North Atlantic is comparatively mild, especially in northwest Europe, including Germany. The winters in other regions at the same latitude are notably colder.

In Canada, for example, the winter temperatures are around ten degrees Celsius lower than in Western Europe. Air currents also contribute significantly to this phenomenon. The distribution of mountain ranges, particularly the Rocky Mountains, which run from north to south along the west coast of North America, together with the influence of the Coriolis force, causes the formation of very stable, large-scale vortices in the atmosphere called standing planetary waves.

Such a vortex lies above the USA because the Rocky Mountains act as an obstacle to divert large air masses.

As a consequence the winds are predominantly westerly over the Atlantic carrying relatively mild air to northwest Europe, and fend off the cold from the east. In the southern hemisphere, only the Atlantic transports heat to the north positive values. The equator lies at zero degrees. The Atlantic and Pacific each carry around one petawatt of heat as far as 20 degrees north latitude.

Further to the north, the Atlantic carries more than the Pacific. The Indian Ocean, on the other hand, makes a negligible contribution to northward heat transport. Oceans contribute to the global transport of heat with different intensities.

The uncertain future of sea ice Sea ice in the Arctic regions has a significant impact on heat exchange between the atmosphere and ocean, because it acts as an insulating layer to prevent heat from escaping from the water. Considering how large the area of ice is, it is clear that it must have an impact on the global climate. In the Arctic Ocean the sea ice, which is commonly called pack ice, has an average thickness of three metres.

In the Southern Ocean it averages around one metre. The total area of sea ice expands and recedes with the seasons. On a yearly average around seven per cent of the oceans about 23 million square kilometres is covered with ice, which is equal to about three times the size of Australia.

By comparison, the ice masses on land are relatively stable. They permanently cover around ten per cent of the land surface Scientists call the ice-covered areas of the Earth the cryosphere. In addition to land and sea ice, this also includes the shelf ice, the parts of continental ice sheets that extend into the ocean.

Changes in the sea ice, including its extent, areal coverage, thickness, and movement, are caused by dynamic processes such as ocean currents and by thermodynamic processes such as freezing and melting. These, in turn, are influenced by solar radiation as well as the heat flux at the sea surface. One of the most conspicuous and important characteristics of climate fluctuations is the change in sea-ice extent in the polar regions.

During some winters the Arctic sea ice extends much further to the south than in others. Sea ice forms a boundary between the two large components of the Earth system, the atmosphere and the ocean, and very significantly influences their interaction. Sea ice has a strong reflective property, called albedo, and it reflects a considerable amount of the incoming sunlight.

This effect is enhanced when the ice is covered with snow. The sea ice therefore influences the radiation balance of the Earth and thus plays an important role in the climate system. The impact of sea ice on climate is further amplified by its insulating effect between the atmosphere and ocean. It inhibits the exchange of heat and wind energy between the atmosphere and ocean considerably. The atmosphere is therefore much colder above the sea-ice surface than above the open ocean.

This has the effect of increasing the air-temperature difference between the tropics, subtropics, and the polar regions. In warmer regions the air has a greater tendency to rise, which lowers the air pressure significantly. By contrast, in very cold regions the air is heavier, and high pressure zones are created. However, these areas do not constantly get warmer and warmer, because the ocean currents and winds transport the heat from the lower latitudes near the equator to higher latitudes near the poles.

Large quantities of heat can be absorbed and stored in the surface layers of the ocean. This heat is transported by ocean currents. In this way, the ocean currents help regulate Earth's climate by facilitating the transfer of heat from warm tropical areas to colder areas near the poles.

The global wind patterns cause the surface currents to form in the uppers layer of the ocean. Where these winds blow in the same direction for long periods of time, large currents develop and transport vast amounts of water over long distances.

As these currents flow along the edges of continents, they affect the temperature of the coastal regions. Along the east coast of the U. Cooler water is more dense so it begins to sink. As a result, the surface currents and the deep currents are linked. Wind causes surface currents to transport water around the oceans, while density differences cause deep currents to return that water back around the globe Figure As you have seen, water that has greater density usually sinks to the bottom.

However, in the right conditions, this process can be reversed. Denser water from the deep ocean can come up to the surface in an upwelling Figure Generally, an upwelling occurs along the coast when wind blows water strongly away from the shore. As the surface water is blown away from the shore, colder water from below comes up to take its place. This is an important process in places like California, South America, South Africa, and the Arabian Sea because the nutrients brought up from the deep ocean water support the growth of plankton which, in turn, supports other members in the ecosystem.

Upwelling also takes place along the equator between the North and South Equatorial Currents. Skip to main content. The Ocean. Search for:. Ocean Currents Ocean water is constantly in motion Figure The direction that they spin depend on the hemisphere that they are in. Licenses and Attributions.

CC licensed content, Shared previously. It all starts with surface currents carrying warm water north from the equator.

The water cools as it moves into higher northern latitudes, and the more it cools, the denser it becomes. In the North Atlantic Ocean, near Iceland, the water becomes so cold that sea ice starts to form. The salt naturally present in seawater does not become part of the ice, however. It is left behind in the ocean water that lies just under the ice, making that water extra salty and dense.

The denser water sinks, and as it does, more ocean water moves in to fill the space it once occupied. This water also cools and sinks, keeping a deep current in motion. These currents circulate around the globe in a thousand-year cycle. The Coriolis effect makes storms swirl clockwise in the Southern hemisphere and counterclockwise in the Northern Hemisphere. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.

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