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.
Such movements of huge masses of water have a global impact on the weather in a given region of the planet and on the Earth’s climate as a whole. In the
Southern Hemisphere, such an effect is exerted by a powerful cold current, called the westerly winds.
Causes of sea currents
The water of the oceans in different regions of the planet varies in temperature, density, salinity, color and cannot physically represent a single conglomerate. Its movement is usually caused by the combined action of several forces acting differently at different depths.
On the surface of the ocean, the main factor in the formation of currents is the prevailing winds. The trade winds, which have a relatively constant direction, are called the main reason for the formation of two main streams that maintain their direction for a long time: the Northern and Southern equatorial currents. They pump water to the western outskirts of the Atlantic and the Pacific Ocean, where, depending on the shape of the continents, separate flows form. Circulations are formed, which are supported, among other things, by monsoon winds blowing in summer from the sea to land, and vice versa in winter.
Warm and cold
The oceans are the global air conditioning of the planet, which has several temperature conditions. Among the types of translational motion of water, warm and cold currents are distinguished. The temperature of the sea stream is not absolute, but relative. It is made warmer by a cooler environment, and cold - by flowing in heated ocean layers and in the hottest climate.
Typically, the current directed from the equator, from high latitudes to lower ones, is warm. If the stream originated south or north of the equator and carries water from a cooler region, then this is a cold current.
The relative temperature characteristics of ocean currents can be seen in the example of two ocean currents located in opposite places of the planet. The Gulf Stream, the most famous sea current that forms the climate in the Northern Hemisphere, has a water temperature in the range of 4-6 ° C and belongs to the warm, warming washed beaches. A powerful cold current is the Bengel - one of the branches of the current of the West winds. Past the Cape of Good Hope, it carries water heated to 20 ° C.
Along the Antarctic border
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) current, encircling the entire planet from west to east with a continuous ring. The largest cold current is the main content of the conditional geographic formation - the Southern Ocean, formed by the waters of the Pacific, Indian and Atlantic oceans, washing the Antarctic.
Along the shores of the sixth continent, at 55 ° south latitude, the conditional southern boundary of this stream passes, and the northern one runs along the 40th parallel. At the junction of cold coastal waters, the strongest winds of the southern hemisphere are born from the ice-covered southern continent and the heated southern ocean outskirts.
Roaring forties
This is another name that the West Winds bear on the planet.
The latitudes along which the largest cold current flows have been given several extreme names. The “roaring” forties surround the “howling” and “frantic” fifties and “piercing” sixties. The average wind speed in this area is 7-13 m / s. According to the Beaufort scale, such a wind is called fresh and strong, and a storm and a strong storm (25 m / s) are commonplace.
A powerful circumpolar cold current that does not meet continental obstacles, strong and constant westerly winds made these latitudes the shortest way for sailing ships. Here ran 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 round the southern extremities of Africa and South America.
Width, length, current velocity
The sea current of the South winds with a total length of 30,000 km and a width of up to 1000 km has a capacity (volumetric water flow) of 125-150 Sv (sruprups), 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 flow velocity in the surface layer of ocean waters is from 0.4 to 0.9 km / h, in depth - up to 0.4 km / h.
The water temperature of the Antarctic circumpolar current is different in its largest branches flowing in three different oceans. The course of the Westerly winds consists of:
- Falkland and Bengal currents in the Atlantic.
- Western Australian - in the Indian Ocean.
- Pacific Peruvian current.
In the southern part of the stream, the upper layer of the stream has a temperature of 1-2 ° C, in the northern - 12-15 ° C.
On the surface and deep
The oceans are a single organism. It has been established that in the ocean the entire water column is in constant motion. Horizontal movements are supplemented by vertical movements, when less dense or more heated layers rise upward. The study of previously inaccessible deep currents, which are often opposite in surface direction, continues.
In 2010, Japanese scientists discovered a powerful deep current off the coast of Antarctica, in the region of Adele’s Land. Water flows from the melting glaciers into the Ross Sea, forming a stream with a capacity of 30 million m 3 / s at a depth of 3000 meters. The flow rate is 0.7 km / h and the water temperature is + 0.2 ° C. This is the coldest current in the South Sea.