Ocean familiarization
Oceans and the seas that connect them cover some 73% of the surface of the Earth, with a mean depth of 3729 m (12,234 ft) (table). More than 70% of the oceans have a depth between 3000 and 6000 m (10,000 and 20,000 ft). Less than 0.2% of the oceans have depths as great as 7000 m (23,000 ft).This planet is approximately 71% water and contains (5) five oceans, including the Arctic, Atlantic, Indian, Pacific and Southern. The ocean is one of the major subdivisions of the interconnected body of salt water that occupies almost three-quarters of the Earth's surface. Earth is the only planet in the solar system whose surface is covered with significant quantities of water. Of the nearly 1.4 billion cubic kilometers of water found either on the surface or in relatively accessible underground supplies, more than 97% is in the oceans.
Of the major units that comprise the world ocean, three—the Atlantic, Indian, and Pacific oceans—extend northward from Antarctica as huge “gulfs” separating the continents. The fourth, the Arctic Ocean, nearly landlocked by Eurasia and North America and nearly circular in outline, caps the North Polar Region. The Southern Ocean (also called the Antarctic Ocean) is now often considered a fifth, Separate Ocean, extending from the shores of Antarctica northward to about 60°S. The major oceans are further subdivided into smaller regions loosely called seas, gulfs, or bays. Some of these seas, such as the Sargasso Sea of the North Atlantic Ocean, are only vaguely defined, while others, such as the Mediterranean Sea or the Black Sea, are almost totally surrounded by land areas. Large and totally landlocked saltwater bodies such as the Caspian Sea are actually salt lakes.
Surface Area of the Planet (510,066,000 sq km)
Land Area on the Planet (148,647,000 sq km) 29.1%
Ocean Area (335,258,000 sq km)
Total Water Area (361,419,000 sq km) 70.9%
Type of Water (97% salt), (3% fresh)
For many years only (4) four oceans were officially recognized, and then in the spring of 2000, the International Hydrographic Organization established the Southern Ocean, and determined its limits. Those limits include all water below 60 degrees south, and some of it, like the Arctic Ocean, is frozen.
(Oceans by size)
#1 Pacific (155,557,000 sq km)
#2 Atlantic (76,762,000 sq km)
#3 Indian (68,556,000 sq km)
#4 Southern (20,327,000 sq km)
#5 Arctic (14,056,000 sq km)
(greatest depths in the oceans) (by ocean)
Mariana Trench, Pacific 35,827 ft
Puerto Rico Trench, Atlantic 30,246 ft
Java Trench, Indian 24,460 ft
Arctic Basin, Arctic 18,456 ft
Southern Ocean (greatest depth in dispute)
(deepest oceans and seas)
#1 Pacific Ocean (35,837 ft) (10,924 meters)
#2 Atlantic Ocean (30,246 ft) (9,219 meters)
#3 Indian Ocean (24,460 ft) (7,455 meters)
#4 Caribbean Sea (22,788 ft) (6,946 meters)
#5 Arctic Ocean (18,456 ft) (5,625 meters)
#6 South China Sea (16,456 ft) (5,016 meters)
#7 Bering Sea (15,659 ft) (4,773 meters)
#8 Mediterranean Sea (15,197 ft) (4,632 meters)
#9 Gulf of Mexico (12,425 ft) (3,787 meters)
#10 Japan Sea (12,276 ft) (3,742 meters)
The creature is amazing in design, where two different seas meet there is a barrier between them that divide them so that each sea has its own temperature, salinity and density- for example the Mediterranean Sea water is warm, saline and less dense compare to Atlantic sea water. When Mediterranean sea water atlantics over the Gibraltar sill it move several hundred kilometer into the Atlantic at depth of about 1000 meters wit hits own warm, saline and less dense characteristics. The Mediterranean water stabilized at this death. Thus there is are large wave ands and string currents and tides in these seas, they do not mix or transgress these barrier.
Estuarine are places where fresh (sweet) and salt water meet, the situation is somewhat different from what you found in places where two sea meet. It has been discovered that what distinguishes fresh and salt water in estuarine is a pycnoclline zone with marked density discontinuity separating the two layers,. This partition (zone of partition) has a different salinity from the fresh water and from the salt water
This information are provided from advanced equipment that measure salinity, temperature, density, oxygen dissolubility etc .the human eye cannot see the difference between the two seas that are then appearing to us as one homogeneous sea that meet. Likewise the human eyes cannot see the division of water in estuarine into the three kinds: fresh water, salt water and the partition (zone of separation).
Another phenomenon is the darkness found in the deep seas and oceans around a depth of 200 meters below .at this depth there is no light at all. Human being are not able to dive or that forth meters without the aid of submarine or special equipment .human cannot survive unaided in the deep dark part of the ocean, such as at a depth of 200 meters. The deep water of the sea and ocean are cover by waves called internal waves which occur on density interfaces between layers of different density and above these waves are other waves. It is clear that the second set of wave are these on wave that we see, because is believe that above the second waves there are clouds. The internal wave cover the deep waters of the seas and oceans because the deep waters have a higher density than the water above them .internal waves as like surface waves. The can also break just like the surface waves. Internal waves cannot be seen by the human eyes, but they can be detected by studying temperature or salinity changes at a given location.
Ocean sediments are composed of terrigenous, pelagic, and authigenic material. Terrigenous deposits consist of sand, mud, and rock particles formed by erosion, weathering, and volcanic activity on land and then washed to sea. These materials are found mostly on the continental shelves and are thickest off the mouths of large rivers or off desert coasts. Pelagic deposits, which contain the remains of organisms that sink to the ocean floor, include red clays and Globigerina, pteropod, and siliceous oozes. Covering most of the ocean floor and ranging in thickness from 60 to 3,300 metres (200 to 11,000 ft), they are thickest in the convergence belts and in the zones of upwelling. Authigenic deposits consist of such materials as manganese nodules. They occur where sedimentation proceeds slowly or where currents sort the deposits.
main article: Origin of the world's oceans
There are thought to have been two or three primary sources for the primordial water that formed Earth's oceans, with debate as to their relative importance. One is outgassing of steam from the Earth's interior, which contributed to the atmosphere and, once the young planet had sufficiently cooled, produced rain; another being that the numerous comets which impacted with the Earth and added their water to it. Another theory is that Earth once had a ring of ice exactly like Saturn's and as that ring melted the water gravitated towards the planet, and rained down. Panspermia theories about Earth's first creatures are linked to what exactly composed the ring besides ice
Physical properties
The area of the World Ocean is 361 million square kilometers (139 million sq mi), its volume is over 1,340 million cubic kilometers (319 million cu mi), and its average depth is 3,711 meters (12,175 ft). Nearly half of the world's marine waters are over 3,000 meters (9,800 ft) deep [1]. The vast abyssal plains of the deep ocean cover about 40% of the Earth's surface. This does not include seas not connected to the World Ocean, such as the Caspian Sea. The total mass of the hydrosphere is about 1.4 × 10 21 kilograms, which is about 0.023% of the Earth's total mass.
Climate-
One of the most dramatic forms of weather occurs over the oceans: tropical cyclones (also called "typhoons" and "hurricanes" depending upon where the system forms). Ocean currents greatly affect Earth's climate by transferring warm or cold air and precipitation to coastal regions, where they may be carried inland by winds. The Antarctic Circumpolar Current encircles that continent, influencing the area's climate and connecting currents in several oceans.
Ecology
The oceans are home to the majority of plant and animal life on Earth. These lifeforms include:
Radiata
fish
cetacea such as whales, dolphins and porpoises,
cephalopods such as the octopus
crustaceans such as lobsters and shrimp
marine worms
plankton
krill
Economy
The oceans are essential to transportation: most of the world's goods are moved by ship between the world's seaports. Important ship canals include the Saint Lawrence Seaway, Panama Canal, and Suez Canal.The ocean has also contributed significantly to the development and economy of the countries around it. Besides its major transatlantic transportation and communication routes, the Atlantic offers abundant petroleum deposits in the sedimentary rocks of the continental shelves and the world's richest fishing resources, especially in the waters covering the shelves. The major species of fish caught are cod, haddock, hake, herring, and mackerel. The most productive areas include the Grand Banks of Newfoundland, the shelf area off Nova Scotia, Georges Bank off Cape Cod, the Bahama Banks, the waters around Iceland, the Irish Sea, the Dogger Bank of the North Sea, and the Falkland Banks. Eel, lobster, and whales have also been taken in great quantities. All these factors, taken together, tremendously enhance the Atlantic's great commercial value. Because of the threats to the ocean environment presented by oil spills, marine debris, and the incineration of toxic wastes at sea, various international treaties exist to reduce some forms of pollution.
Extraterrestrial oceans
Earth is the only known planet with liquid water on its surface and is certainly the only one in our own solar system. However, liquid water is thought to be present under the surface of several natural satellites, particularly the Galilean moons of Europa, and, with less certainty, Callisto and Ganymede. Geysers have been found on Enceladus. Other icy moons may have once had internal oceans that have now frozen, such as Triton. The planets Uranus and Neptune may also possess large oceans of liquid water under their thick atmospheres, though their internal structure is not well understood at this time.There is currently much debate over whether Mars once had an ocean of water in its northern hemisphere, and over what happened to it if it did; recent findings by the Mars Exploration Rover mission indicate it had some long-term standing water in at least one location, but its extent is not known.
Natural hazards
Icebergs are common in the Davis Strait , Denmark Strait , and the northwestern Atlantic Ocean from February to August and have been spotted as far south as Bermuda and the Madeira Islands . Ships are subject to superstructure icing in extreme northern Atlantic from October to May. Persistent fog can be a maritime hazard from May to September, as can hurricanes north of the equator (May to December).The Bermuda Triangle is popularly believed to be the site of numerous aviation and shipping incidents because of unexplained and supposedly mysterious causes, but coast guard records do not support this belief.
Current environmental issues
Endangered marine species include the manatee, seals, sea lions , turtles , and whales. Drift net fishing is killing dolphins , albatrosses and other seabirds ( petrels , auks ), hastening the decline of fish stocks and contributing to international disputes. There is municipal sludge pollution off the eastern United States , southern Brazil, and eastern Argentina ; oil pollution in the Caribbean Sea, Gulf of Mexico, Lake Maracaibo , Mediterranean Sea, and North Sea; and industrial waste and municipal sewage pollution in the Baltic Sea, North Sea, and Mediterranean Sea.On June 7, 2006 , Florida's wildlife commission voted to take the manatee off of the state's endangered species list. Some environmentalists worry that this could erode safeguards for the popular sea creature.
Quotes:
The ocean moans over dead men's bones. - Thomas B. Aldrich
A body of water occupying about two-thirds of a world made for man, who has no gills. - Ambrose Bierce
Roll on, deep and dark blue ocean, roll. Ten thousand fleets sweep over thee in vain. Man marks the earth with ruin, but his control stops with the shore. - Lord Byron
Praise the sea; on shore remain. - John Florio
He that will learn to pray, let him go to sea. - George Herbert
I must go down to the sea again, to the lonely sea and the sky; and all I ask is a tall ship and a star to steer her by. - John Masefield
The sea complains upon a thousand shores. - Alexander Smith
The ocean really mighty , beside all of the the above, the ocean contain a lot mineral resouces , seabed mining is being adminiter by the UN agency for ocean affairs, having headquaterin Jamaica.
oladokuns@yahoo.com
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