Glancing at the map of the hemispheres can be seen uneven distribution of land and water on the planet's surface.Huge continents scattered on the world's oceans, like islands.In the Southern Hemisphere, the share of land accounts for less than 20%, in the North - about 40%.What is called the world's oceans in geography, ecology and other earth sciences?This is the most significant part of the hydrosphere - water shell of our planet.How many oceans on Earth, some of them the largest in area and the warmest?On these and many other questions are answered in the proposed article.
What is called the world's oceans (MO)?
All the water on the Earth forms a single envelope, part of which relate cycle of H2O molecules and other substances.Defense - is a continuous part of the hydrosphere, which accounts for over 94% of the total area of water on the planet (oceans, seas, bays, straits, rivers, lakes and ponds).Usually Russian scientists geographers allocate 4 basic parts of the oceans.We list them in order of the surface area (mln. Km2) Quiet (179), Atlantic (92), Indian (76), the Arctic (15).
As people learned of the existence of the relationship between the oceans?
person has long attracted huge seas.Very early on fragile boats, rafts and catamaran fishermen were sent into dangerous water travel.The history of the oceans mentions the ancient descriptions, stories, legends about overcoming rafting, rowing and sailing ships huge distances.It is believed that the population of the continents and islands in ancient times occurred due to the ability of people to overcome the oceans and seas.
first known trip around the world made the Spanish fleet under the leadership of Ferdinand Magellan in 1519-1522 years.Moving from the Iberian Peninsula to the west, the ships crossed the Atlantic, rounded South America, entered into unknown waters.The weather was windless, so Magellan named the Pacific Ocean.In a skirmish with the natives in the Philippines, many Spanish sailors together with the head of the expedition died.Companions Magellan continued to travel west in search of spices, gold and precious to the Spanish crown.
One of the ships led by Captain Juan Elcano crossed the central part of the Indian Ocean, rounded Africa to the south and returned to Europe.So it was proved sphericity of the Earth, the existence of even one part of the world's oceans.Circumnavigation and other travel in the Age of Discovery marked the beginning of a large-scale study of water spaces for trade, science, industry and fishery.
Defense - the main part of the hydrosphere
In studying the topic "World Ocean" (Grade 7) it is necessary to recall previously learned material Class 6 ("hydrosphere").Uniform water shell of the Earth consists of two unequal in size parts - Defense of water and land.They linked the cycle of matter and energy, the transfer of moisture, surface and groundwater runoff.What is called the world's oceans in modern science?The term used in relation to a large expanse of water from the XVII century through the work of the German-Dutch researcher Bernhard Varenius.
Russian scientist YM Shokalsky at the beginning of the XX century introduced into scientific use the term "World Ocean", highlighted 4 main parts of Defense.This huge size oceanic natural complexes, separated by continents and archipelagos (chain of islands).Minor branches MO - bays, straits, sea (Marginal).
traditional division of the Ministry of Defense on
boundaries are often conditional, as there is a single stretch of water - the oceans.MO map provides insight into the variety of dividing lines.For example, the Pacific Ocean and the Arctic are separated by the peninsula (Chukotka and Alaska), linked the narrow Bering Strait.The boundary between the Atlantic and the Indian Ocean south of Africa is carried out at 20 °.d.
in some countries can be divided the bulk of the hydrosphere on 5 or 7 separate regions.In these cases, added the Southern Ocean and two Atlantic.Depending on the country of residence for the response to the usual school curriculum question "What is called the world's oceans?" Differs in the number of allocation units in its composition (the Earth's oceans).
science of the oceans and parts of
study of bottom topography, temperature, salinity, currents and other features of large bodies of water involved in oceanography (section geography).Different parts of the MoD differ in solute content, density, measurements which are carried out with the help of modern instruments in the tens of thousands of points.
certain depths using echolocation allowed to count the total number of sea water in the world, and of dissolved compounds (chlorides, sulfates, iodide, of practical importance).The waters of the oceans have an average density of 1.024 g / cm3.Such liquid does not freeze at 0 ° C, and at -1 ... -3 ° C.The deeper, the lower the temperatures depend on the geographical latitude.
depth of the oceans
How do you know the maximum and minimum distance from the surface of the bottom?What is the depth at which the oceans differ?MO map contains information about the average and maximum depths.Maritime space marked with various shades of blue.The dark color of the maps correspond to the deepest places.
light blue color is used to display the shallows of mid-ocean ridges.The deepest is considered the Pacific Ocean, in the north-western part of the Mariana Trench depth is more than 11 km.At the western coast of Chile held Peruvian Trench (about 7 km).And the average depth of 3.7 km MO.
bottom relief
continuation of the continents under water - it's continental shelf, it reaches a depth of 1 km in some places.Oceans around the perimeter has one transition zone - the continental slope.Within the limits of the continental shelf are allocated different origin plains have dipped deep areas in the Sea of Okhotsk, the Barents Sea and the Sea of Japan.Seafloor covers the central part of the bottom and is a different shape and size of the basin, a hill.Trench clashes occurred in areas of oceanic lithospheric plates with continental.
Among the mountain structures of the seabed is dominated mid-ocean ridges and shafts, which are connected into a single continuous chain which is over 40 thousand. Km.In addition, the ocean floor is isolated blocky and volcanic ridges, arrays and single underwater peaks.Other forms of bottom relief - plateaus and hills.
Movement of water in the MO
different reasons and natural phenomena cause the movement of water masses in the oceans:
- water movement up and down are caused by the wind;
- constant air flow lead to the formation of currents;
- tides cause the attraction of water of the oceans to the moon;
- the eruption of underwater volcanoes appear giant wave - a tsunami.
MO The maps in atlases flow indicated by the arrows red and blue colors.Color conveys such a feature as a high or low temperature for comparison with the ocean environment.The largest warm water streams: the Gulf Stream in the north-west Atlantic, the Kuroshio near the Japanese islands, the North Atlantic Current.Cold water flows into the MO: for the Western winds, Peru, Benguela.
water temperature MO
polar and subpolar part of the Ministry of Defense - the coldest.The large surface area of the Arctic Ocean covered by perennial ice thickness big.In the Arctic and Antarctic ice fields there and boulders in the water - icebergs.The coldest ocean - the Arctic, much of which constrained the ice year-round.As we move from the Arctic Circle to the temperate zone, the Northern and Southern Tropics more water heated by the sun.The warmest it considered the Pacific Ocean, the most extensive in the hot zone lighting.
surface water temperature changes faster.As a rule, the main stream of solar energy does not penetrate into the depths.Therefore, in the summer in temperate and tropical latitudes, the surface water temperature is higher than in winter.At greater depths seasonal differences almost not felt.When moving from the surface of a few hundred meters noticeably strong decrease in temperature.Over 1 thousand. Meter changes are less pronounced, and less than 3 thous. M, the temperature is always between + 2 ° ... 0 ° C.
MO Influence on climate continents
Oceans is important for the formation of climate and weather on land.The average surface temperature of MO 17,4 ° C, whereas at the Earth's surface, the figure is 14,4 ° C.Oceans are able to exert a significant influence on the exchange of heat and moisture between the atmosphere and land.The water heats and cools more slowly than the continents and islands, because of the high specific heat capacity.
cold currents move water masses in the warmer regions, and vice versa.These processes have a great impact on the distribution of pressure and temperature.In winter, MO is a kind of "stove" for heating over the world, and in the summer - "refrigerator."Existing problems of the oceans - the melting of ice, rising water levels - threaten to change the climate and vegetation on the continents, disaster.
salinity in sea water in various amounts are present in almost all the elements of the periodic table.The average content of various salts is 3.5%.It applies special unit - ppm - shows the number of grams of solute in 1 liter of seawater (0/00).The average salinity of Defense - 35 0/00.The connection between geography, distribution of surface currents, evaporation, salinity and other properties, which differ Oceans.Water Resources Defense far exceed supplies by land.To extract useful compounds used evaporation, for drinking water - special desalination plants on ships, and in coastal areas of many countries.
significant amount of salts accumulate waters of the ocean, which are between 45 ° C.w.and 10 ° S.w.The content of substances in seawater depends on runoff from the mainland, the thickness of the ice and its melting.Most of the salt MO confined to tropical latitudes.This north-western part of the Indian Ocean - the Red Sea and Bab-el-Mandeb (41 and 42 ‰ respectively).The salinity of the Mediterranean Sea is 39 ‰.
Natural Resources Defense
store valuable chemicals, fuel, source of energy, fresh water, food, a home for many living organisms - all the oceans.Geography mineral reserves has not been studied at great depths, and offshore development is many decades.Most valuable are the following Natural Resources Defense:
- fuel (oil, gas, coal);
- metallic and non-metallic minerals (salt, iron, manganese, bromine, calcium, gold, diamonds, amber, titanium, tin);
- energy (tides, waves, hot springs);
- construction materials (sand, gravel);
- supplies of water desalination;
- fish, marine mammals, crustaceans, molluscs, sponges;
- vegetable;
- recreation.
long been the oceans, coastal zone resources are used for navigation, sea fishing, cruise and beach relaxation, health recovery.Popular beaches are located on the warm sandy shores of the Mediterranean, the Red and the Black Sea, Atlantic, Indian, Pacific Oceans in the subtropical and tropical climatic zones.
Ecological problems of the oceans are largely due to the growth of mining.When oil spills on the surface of the water forms an airtight film.It violated the exchange of oxygen and carbon dioxide between the atmosphere and the ocean, killing aquatic animals and plants.
«Fish latitude" of the oceans
oceans and seas are areas of intense fishing, mining of coral and pearls.The share of sea fishing accounts for about 10% of food raw materials.Commercial fish of the oceans - is sardines, anchovies, herring, tuna, salmon, hake, capelin, mackerel, rockcod, pollack, cod, halibut, sprat, flounder.
In those latitudes, where there are conditions for the development of plankton, there is an abundance of fish.For reproduction of small organisms suspended in the water, it is necessary that the bottom of the so-called climbing nutrients (nitrogen, silicon, phosphorus, calcium, and others).Such conditions nature has created in many regions of MO:
- the Pacific coast of South America south of the equator;
- near the Labrador Peninsula, from East Greenland to the north;
- near the coasts of Europe and North America in the Atlantic Ocean near 40 °.N .;
- from the coast of Morocco in West Africa to the extreme point in the south of the continent's hot;
- off the coast of Burma in the Indian Ocean, near the islands of Indonesia.
Oceans, as the most significant part of the continuous aqueous shell of the Earth, plays an important role in the world, and its riches are used by man since time immemorial.For individual characteristics of the different MO, but it is a holistic natural complex planetary scale, which must be preserved for the well-being of present and future generations.
