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 influences 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 climate of the Earth as a whole. In the Southern Hemisphere, a powerful cold current called the West Wind Current has this effect.
Causes of sea currents
Water of the World Ocean in different areas of the planet differs in temperature, density, salinity, color and cannot physically represent a single conglomerate. Its displacement 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 direction for a long time: the North and South Equatorial Currents. They pump water tothe western margins of the Atlantic and the Pacific Ocean, where, depending on the shape of the continents, separate streams are formed. Circulations are formed that support, among other things, monsoon winds blowing from the sea to land in summer, and vice versa in winter.
Warm and cold
The World Ocean is the global air conditioner of the planet, which has several temperature regimes. Among the varieties of the translational movement of water, warm and cold currents are distinguished. The temperature of the sea stream is not absolute, but relative. Cooler environments make it warm, and cooler flows in warm ocean layers and in the hottest climates.
Usually, the current directed from the equator, from high latitudes to lower latitudes, is warm. If the stream originated south or north of the equator and carries water from a cooler area, then this is a cold current.
The relativity of the temperature characteristics of ocean currents is seen in the example of two ocean currents located on opposite sides 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 shores. A 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 waters heated to 20°C.
On the border of Antarctica
Large-scale water movements in the circumpolar regions of the Southern Hemisphere are the most powerful on the planet. They form the Antarctic Circumpolar (Latincircum - around + polaris - polar) current encircling the entire planet from west to east in a continuous ring. The largest cold current is the main content 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, 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 from the ice-covered southern mainland and the heated southern ocean margins, the strongest winds of the southern hemisphere are born.
Roaring Forties
This is another name given to the current of the West Winds on the planet.
The latitudes along which the largest cold current flows have been assigned several extreme names. The "roaring" forties surround the "howling" and "raging" fifties and the "piercing" sixties. The average wind speed in this area is 7-13 m/s. On the Beaufort scale, such a wind is called fresh and strong, and a storm and a strong storm (25 m / s) are a common thing.
Powerful subpolar cold current, not encountering continental obstacles, strong and constant westerly winds have made these latitudes the shortest route 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 aroundsouthern tip of Africa and South America.
Width, length, flow speed
The sea current of the South winds with a total length of 30,000 km and a width of up to 1,000 km has a capacity (volume water flow) of 125-150 Sv (swedrups), i.e., the flow carries up to 150 thousand cubic meters of water per second. 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, in depth - up to 0.4 km/h.
The temperature of the water of the Antarctic Circumpolar Current is different in its largest branches, flowing in three different oceans. The course of the West Winds consists of:
- Falkland and Bengal Current in the Atlantic.
- West Australian - in the Indian Ocean.
- Pacific Peru current.
In the southern part of the current, the upper layer of the stream has a temperature of 1-2°C, in the northern part - 12-15°C.
On the surface and in the depths
The oceans are a single organism. It has been established that in the ocean the entire water column is in constant motion. Horizontal displacements are supplemented by vertical ones, when less dense or more heated layers rise up. Research continues on previously inaccessible deep currents, which are often opposite in direction to surface currents.
In 2010, Japanese scientists discovered a powerful deep current off the coast of Antarctica, in the Adélie Land area. Water from melting glaciers flows into the Ross Sea, forming a stream with a capacity of 30 million m3/s at a depth of 3000 meters. The current speed is 0.7 km/h, and the water temperature is + 0.2°C. This is the coldest current in the South Sea.
