Wednesday, March 27, 2013

Oceanography:


1. The Peru-Chile trench is the longest in the world. The only difference between ridge & rises is that ridges are steep sided while rises are gently sloped.

2. Juan de Fuca Strait, is the arm of the Pacific Ocean between Washington & Vancouver.

3. Thermocline is the transition layer between the mixed layer at the surface and the deep water. The various salts in the sea in order of decreasing quantity are NaCl, MgCl, MgSO4, CaSO4.

4. Danube, Dneiper, & Dneister all fall into black sea reducing it salinity.

5. Water moves from areas over which there is a low pressure to areas over which there is a high pressure.

6. The pelagic zone includes those waters further from the land, basically the open ocean. It is divided into neritic zone (having a depth of 200metres) & the oceanic province (separated from the neritic province by the edge of the continental shelf). The benthic zone refers to the sea bottom itself & is divided into littoral zone & deep sea zone. The two zones have their frontier at a depth of 200 meters. Benthos (plants such as kelp, sponges) are organisms that live on the ocean floor while nektons are swimming animals such as fishes & whales.

7. The east pacific rise is known as albatross plateau extending from north of New Zealand to the Californian coast.

8. Oozes are pelagic deposit in the form of liquid mud. There are divided on the basis of content into
calcareous ooze (lime) & siliceous ooze (silica). Calcareous ooze is further divided into pteropod ooze & globigerina (most widespread) ooze. Siliceous ooze is divided into radiolarian (formed of shells of
foraminifera) & diatom ooze.

9. Red clay is the most widely spread pelagic deposit & consists mainly of hydrated silicate of Aluminium & oxides of iron. Neritic deposits consists of dead shells of plants & animals.

10. Atlantic Ocean: The warm North Atlantic Drift (NAD) gives rise to the Irminger Current south of Iceland which travels along western and northwestern coasts of Iceland until it meets East Greenland Current. Another branch of NAD flows along Norway coast forming Norwegian current. Falkland current brings the cold waters of the Antarctic sea northward up to Argentina.

11. Pacific Ocean :Kuroshio (or Kuro Siwo) Current of Pacific is similar to the gulf stream of Atlantic. One branch separates from Kuroshio current & enters the sea of Japan as Tsushima current. The Cold Oyashio (or Oya Siwo) Current (similar to Labrador current) is also known as Kurile current & it flows through the Bering Strait in a southerly direction. The cold Okhotsk current flows past Sakhalin to merge with Oya Siwo current near Hokkaido Island & later mergers with the warm Kuro Siwo current producing dense fogs. The north pacific drift continues later as Aleutian current which divides into two parts – the northern branch becomes Alaska current while the southern branch becomes California cold current (similar to Canary cold current of Atlantic). Cromwell current also called pacific equatorial undercurrent is a submarine river & flows towards east. Mindanao current is a southward flowing boundary current along the Philippine coast.

12. Indian Ocean: One branch of the south equatorial current moves southward through the Mozambique Channel to form the Mozambique Current. This current joins the Agulhas Current & moves to the southern tip of Africa. During the northeast monsoon season the Somali Current flows southward & During the southwest monsoon the current develops into an intense northward jet

13. La Nina is opposite of El Nino & intensifies the Humboldt Current. El Nino causes drought conditions in India, Southern Africa, Australia & heavy rains in Chile, Colorado. The El Nino events of 1982 & 1997 were severe. The Southern Oscillation, a more recent discovery, refers to an oscillation in the surface pressure (atmospheric mass) between the southeastern tropical Pacific and the Australian-Indonesian regions

14. Tahiti is the largest and most important of the Society Islands, in the southern Pacific Ocean. The chief town on the island is Papeete which is also the capital of French Polynesia.

15. In gravity waves (large waves) the restoring force is gravity while in capillary waves (ripples caused by winds) the restoring force is surface tension. Swell refers to long crested waves with longer periods which have traveled out of their source areas. Surf refers to a belt of nearly continuously breaking waves. Internal waves are caused due to density differences. Seiches are standing waves (e.g. Lake Geneva).

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