About 70% of the surface of the globe is occupied by the waters of the World Ocean. They are constantly in motion under the influence of long-term or short-term effects of various origins.
Causes of sea currents
Water of the World Ocean in different areas of the planetit differs in temperature, density, salinity, color and cannot physically represent a single conglomerate. Its movement is usually caused by the cumulative action of several forces acting differently at different depths.
На поверхности океана главный фактор образования currents - the prevailing wind. The trade winds, which have a relatively constant direction, are called the main reason for the formation of two main streams that retain their direction for a long time: the North and South Equatorial Currents. They inject water to the western margins of the Atlantic and the Pacific, where, depending on the shape of the continents, separate streams form. Circulations are formed, which support, among other things, monsoon winds blowing in summer from sea to land, and in winter - vice versa.
Warm and cold
World Ocean - the global air conditioner of the planet,having several temperature conditions. Among the types of translational motion of water distinguish between warm and cold currents. The temperature of the sea stream is not absolute, but relative. He is warmed by a cooler environment, and by a cold one - by flowing in heated ocean layers and in the hottest climate.
The current usually directed from the equator is fromhigh to lower latitudes - warm. If the stream originated to the south or north of the equator and carries water from a cooler region, then this is a cold current.
Relativity of the temperature characteristicOcean currents can be seen on the example of two ocean streams located on opposite parts of the planet. The Gulf Stream is the most famous sea current, which forms the climate in the Northern Hemisphere, has a water temperature in the range of 4-6 ° C and belongs to warm, warmed banks. The powerful cold current is the Benguela, one of the branches of the current of the Western winds. Past the Cape of Good Hope it carries water heated to 20 ° C.
On the border of the Antarctic
Large-scale water movements in the circumpolar regions of the southern hemisphere are the most powerful on the planet. They form the Antarctic Circumpolar (Latin circum - around + polaris - polar) течение, опоясывающее непрерывным кольцом всю the planet from west to east. The largest cold current is the main filling of the conditional geographical formation - the Southern Ocean formed by the waters of the Pacific, Indian and Atlantic oceans, washing Antarctica.
Along the shores of the sixth continent, 55 ° southlatitude, the conditional southern boundary of this stream passes, and the northern one runs along the 40th parallel. At the junction of cold coastal waters from the ice-covered southern continent and the heated southern ocean margins the strongest winds of the southern hemisphere are born.
Roaring Forties
This is another name that bears on the planet during the westerly winds.
The latitudes along which the largest flowscold current, several extreme names are assigned. The "roaring" forties surround the "howling" and "violent" fifties and the "shrill" sixties. The average wind speed in this area is 7-13 m / s. On the Beaufort scale, this wind is called fresh and strong, and the storm and a strong storm (25 m / s) are common.
Powerful circumpolar cold current, notmeeting continental obstacles, strong and constant westerly winds made these latitudes the shortest way for sailboats. Here lay the “clipper route”, named after the type of ships valued for the fastest delivery of colonial goods from India and China to Europe. The famous "tea" clippers set speed records in the 18th-19th centuries if they managed to successfully go around the southern tips of Africa and South America.
Width, length, flow rate
Sea current of the South winds with a total length of 30,000km and a width of up to 1000 km has a capacity (volumetric water flow) - 125-150 Sv (compressed), that is, per second the flow carries up to 150 thousand cubic meters of water. This is comparable to the power that the Gulf Stream has in some places. The speed of the current in the surface layer of ocean waters is from 0.4 to 0.9 km / h, and in depth to 0.4 km / h.
The water temperature of the Antarctic Circumpolar Current varies in its largest branches, flowing in three different oceans. The current of the westerly winds is:
- Falkland and Bengal currents in the Atlantic.
- West Australian - in the Indian Ocean.
- Pacific Peru current.
In the southern part of the flow, the upper layer of the flow has a temperature of 1-2 ° C, in the north - 12-15 ° C.
On the surface and in depth
Oceans - a single organism.It has been established that in the ocean the entire water column is in constant motion. Horizontal movements are complemented by vertical ones, when less dense or more heated layers rise upwards. Research continues on previously inaccessible deep currents, which are often opposite in the surface direction.
In 2010, Japanese scientists discovered off the coastAntarctica, in the area of the Adelie Land, a powerful deep current. Water from melting glaciers flows into the Ross Sea, forming a flow of 30 million meters at a depth of 3000 meters3/with. The flow velocity is 0.7 km / h and the water temperature is + 0.2 ° C. This is the coldest current in the South Sea.
