Tuesday, September 29, 2009

[Sarkari-Naukri] Harish Sati, Geography World & Indian (ocean currents)

Geography - World & Indian (Ocean currents):

 

An ocean current is any more or less permanent or continuous, directed movement of ocean water that flows in one of the Earths oceans. The currents are generated from the forces acting upon the water like the earths rotation, the wind, the temperature and salinity differences and the gravitation of the moon.

Ocean currents can flow for thousands of kilometers. They are very important in determining the climates of the continents,especially those regions bordering on the ocean.

 

Direction
Surface ocean currents are generally wind driven and develop their typical clockwise spirals in the northern hemisphere and counter-clockwise rotation in the southern hemisphere because of the imposed wind stresses. In wind driven currents, the Ekman spiral effect results in the currents flowing at an angle to the driving winds. The areas of surface ocean currents move somewhat with the seasons; this is most notable in equatorial currents.

Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation, also known as the oceans conveyor belt, refers to the deep ocean density-driven ocean basin currents.

Ocean currents are measured in Sverdrup with the symbol Sv, where 1 Sv is equivalent to a volume flow rate of 106 cubic meters per second.

 

Warm ocean currents are corridors of warm water moving from the tropics poleward  where they release energy to the air. Cold ocean currents are corridors of cold water moving from higher latitudes toward the equator. They absorb energy received in the tropics thus cooling the air above

Major Ocean currents

Current Ocean Type
Agulhas Current Indian Warm
Alaska Current North Pacific Warm
Benguela Current South Atlantic Cool
Brazil Current South Atlantic Warm
California Current North Pacific Cool
Canaries Current North Atlantic Cool
East Australian Current South Pacific Warm
Equitorial Current Pacific Warm
Gulf Stream North Altantic Warm
Humboldt (Peru) Current South Pacific Cool
Kuroshio (Japan) Current North Pacific Warm
Labrador Current North Atlantic Cool
North Atlantic Drift North Atlantic Warm
North Pacific Drift North Pacific Warm
Oyashio (Kamchatka) Current North Pacific Cool
West Australian Current Indian Cool
West Wind Drift South Pacific Cool

 

El Niño and La Niña
Peruvian fisherman in the late 1800s named the seasonal swing of ocean water "El Niño" (Spanish for the "Christ Child") as it usually occurred around Christmas. A periodic weakening of the trade winds in the central and western Pacific allows warm water to invade the eastern Pacific. Along the Peruvian coast, the encroaching warm water displaces the nutrient-rich north-flowing cold ocean current causing a decline in fisheries. Today, the phenomenon is known as the " El Niño/Southern Oscillation" and we are coming to understand how this change in the seasonal wind and ocean circulation impacts global weather patterns (See December - February conditions; June - August conditions). Cooler than normal ocean temperature in this region is called "La Niña". It too has significant impacts on worldwide weather.



--
with warm regards

Harish Sati
Indira Gandhi National Open University (IGNOU)
Maidan Garhi, New Delhi-110068

(M) + 91 - 9990646343 | (E-mail) Harish.sati@gmail.com


--~--~---------~--~----~------------~-------~--~----~
You have subscribed to the Groups "Sarkari-naukri" of http://sarkari-naukri.blogspot.com at Google.com.
Send email to Sarkari-naukri@googlegroups.com for posting.
Send email to
Sarkari-naukri-unsubscribe@googlegroups.com to unsubscribe.
Visit this group at
http://groups.google.com/group/Sarkari-naukri?hl=en
-~----------~----~----~----~------~----~------~--~---

Please Visit For Funny pictures::: http://funnypicsz.blogspot.com/

No comments:

Post a Comment