What is called the world's oceans? The World Ocean: Resources

Looking at the physical map of the hemispheres, you can see the uneven distribution of land and water on the surface of the planet. Huge continents are scattered on the expanses of the World Ocean like islands. In the Southern Hemisphere, land accounts for less than 20%, in the Northern - about 40%. What is called the World Ocean in geography, ecology and other sciences about the Earth? This is the most significant part of the hydrosphere - the water shell of our planet. How many oceans are there on Earth, which one is the largest in area and the warmest? These and many other questions are answered in the proposed article.

What is called the World Ocean (MO)?

All water on Earth forms a single shell, parts of which are connected by a cycle of H2O molecules and other substances. MO is a continuous part of the hydrosphere, accounting for more than 94% of the total water area on the planet (oceans, seas, bays, straits, rivers, lakes and ponds). Usually Russian scientists-geographers distinguish 4 main parts of the World Ocean. Let us list them in descending order of the surface area (million km ² ): Pacific (179), Atlantic (92), Indian (76), Arctic (15).

How did people learn about the relationship between the oceans?

For a long time people have been attracted to huge sea spaces. Already in ancient times, on fragile boats, rafts and catamarans fishermen went on dangerous water travel. The history of the World Ocean mentions ancient descriptions, legends, legends about overcoming on rafts, oars and sailing vessels of huge distances. It is believed that the settlement of continents and islands in antiquity was due to the ability of people to overcome the oceans and seas.

The first known round-the-world trip was made by a Spanish squadron led by Fernand Magellan in 1519-1522. Moving from the Iberian peninsula to the west, the ships crossed the Atlantic Ocean, rounded South America, entered unknown waters. The weather was windless, so Magellan called the ocean Quiet. In the skirmish with the aborigines in the Philippines, many Spanish sailors along with the head of the expedition were killed. Magellan's associates continued their journey to the west in search of spices, gold, jewels for the Spanish crown.

One of the ships under the leadership of Captain Juan Elcano crossed the central part of the Indian Ocean, rounded Africa from the south and returned to Europe. Thus, the sphericity of the Earth was proved, the existence of yet another part of the World Ocean was established. Round-the-world voyage and other trips in the era of the Great Geographic Discoveries marked the beginning of a large-scale study of water spaces in the interests of trade, science, industry and fisheries.

MO is the main part of the hydrosphere

When studying the theme "World Ocean" (Grade 7), it is necessary to recall the previously studied 6th class material ("Hydrosphere"). The unified water envelope of the Earth is two unequal in size parts - MO and land water. They are interconnected by a cycle of substances and energy, moisture transfer, surface and underground runoff. What is called the world ocean in modern science? The term itself has been applied to large water areas since the 17th century thanks to the works of the German-Dutch explorer Bernhard Warenius.

Russian scientist Yu. M. Shokalsky at the beginning of the 20th century introduced the term "World Ocean" into scientific use, singled out 4 main parts of the Moscow Region. These are huge in size oceanic natural complexes, separated from one another by continents and archipelagos (island chains). Minor offshoots of the Ministry of Defense - bays, straits, seas (suburban and internal).

Traditional division of the MO in part

Borders are often conditional, since there is a single water space - the World Ocean. The MO map gives an idea of the diversity of the separation lines. For example, the Pacific Ocean and the Arctic Ocean are separated from each other by peninsulas (Chukchi and Alaska), connected by a narrow Bering Strait. The boundary between the Atlantic and Indian oceans to the south of Africa runs through the 20th century. E.

In a number of countries it is common to divide the main hydrosphere array into 5 or even 7 isolated regions. In these cases, the Southern Ocean and two parts of the Atlantic are added. Depending on the country of residence, the answer to the usual question for the school program, "What is called the World Ocean?" Differs in the number of parts it allocates (oceans of the Earth).

The Science of the World Ocean and Its Parts

The study of the relief of the bottom, temperature, salinity of waters, currents and other features of large water spaces deals with oceanography (geography section). Different parts of the MO differ in content of dissolved substances, density, measured by modern devices in tens of thousands of points.

Determination of depths with the help of echolocation allowed us to calculate the total amount of sea water on the Earth and the compounds dissolved in it (chlorides, sulphates, iodides, having practical significance). The waters of the World Ocean have an average density of 1,024 g / cm ³ . Such a liquid does not freeze at 0 ° C, but at -1 ... -3 ° C. The deeper, the lower the temperature values depend on the geographical latitude.

Depth of the World Ocean

How do you know the largest and smallest distances to the bottom surface? What are the depths of the World Ocean? The MO map contains information about the mean and maximum depth. The sea spaces are marked with different shades of blue. Dark color on the cards corresponds to the deepest places.

Light-blue color is used to display shallows, mid-ocean ridges. The deepest is the Pacific Ocean, in its north-western part is the Mariana Trench with a depth of more than 11 km. Near the western coast of Chile is the Peruvian trench (about 7 km). And the average depth of the MO is 3.7 km.

Bottom relief

Continuation of the surface of the continents under water is a continental shelf, its depth sometimes reaches 1 km. The world ocean along the perimeter has one more transition zone - the continental slope. Within the continental shelf, there are various plains of origin, there are deeply depressed areas in the Okhotsk, Barents and Japan seas. The bed of the ocean covers the central parts of the bottom and represents different in form and size basins, elevations. Deep-sea troughs arose in the areas of collision of oceanic lithospheric plates with continental slabs.

Among the mountain structures of the seabed, mid-oceanic shafts and ridges predominate, which are connected in a single continuous chain with a length of over 40,000 km. In addition, on the bed of the ocean, there are blocky and volcanic ridges, arrays and single underwater peaks. Other forms of the bottom relief are plateaus and elevations.

Movement of water in the MO

Various causes and phenomena of nature cause the movement of water masses in the World Ocean:

• Water movements up and down occur under the influence of wind;
• Constant air currents lead to the formation of currents;
• Tides and ebbs cause the attraction of the water of the World Ocean to the Moon;
• As a result of eruptions of underwater volcanoes there are giant waves - a tsunami.

On the maps of the MO in the atlases the currents are indicated by arrows of red and blue color. Color conveys such a feature as a higher or lower temperature in current compared to the environment of the ocean. The largest warm watercourses: the Gulf Stream in the northwestern Atlantic, Kuroshio near the Japanese islands, the North Atlantic Current. Cold water flows in the MO: during the Western winds, Peru, Benguela.

Water temperature MO

Polar and circumpolar parts of the MO are the coldest. The considerable surface area of the Arctic Ocean is covered with perennial ice of great thickness. In the Arctic and Antarctic there are ice fields and blocks in the water - icebergs. The coldest ocean is the Arctic Ocean, a significant part of which is frozen all year round. As you move from the Polar Circles to the temperate zones, the Northern and Southern tropics, the water is more heated by the Sun. The warmest is the Pacific Ocean, the widest in the hot belt of illumination.

The surface water temperature changes faster. As a rule, the main stream of solar energy does not penetrate to the depth. Therefore, in summer in temperate and tropical latitudes the water temperature on the surface is higher than in winter. At great depths, seasonal differences are almost not felt. When moving from the surface the first hundred meters is noticeably a strong drop in temperature. Over 1 thousand meters of changes are less pronounced, and below 3 thousand meters the temperature is constantly in the range of +2 ° ... 0 ° С.

The influence of MO on the climate of continents

The global ocean is important for the formation of climate and weather on land. The average temperature of the MO surface water is 17.4 ° C, while at the Earth's surface this figure is 14.4 ° C. Oceans can have a significant effect on the exchange of heat and moisture between the atmosphere and the land. Water heats up and cools more slowly than continents and islands, because of the large specific heat.

Currents move cold water masses to warmer regions, and vice versa. These processes have a large impact on the distribution of pressure and air temperatures. In winter, the MO is a kind of "stove" for heating the continents, and in the summer - a "refrigerator". The existing problems of the World Ocean - melting ice, raising the water level - threaten the climate and vegetation on the continents and natural disasters.

Salinity

In sea water in various quantities, there are almost all elements of the periodic table. The average content of various salts is 3.5%. A special unit of measure is used - ppm, - indicating the amount of dissolved substances in grams per liter of sea water ( _0/00 ) _. The average salinity index of the MO is 35 _0/00 . The relationship between the geographical location, the distribution of surface currents, the volatility, salinity and other properties that distinguishes the World Ocean is traced. The water resources of the MoD far exceed the reserves on land. For the extraction of useful compounds, evaporation is used, for the production of drinking water, special desalination plants on sea vessels and in the coastal regions of many countries.

A significant number of salts accumulate ocean waters, which are between 45 ° N. W. And 10 ° S. W. The content of substances in sea water depends on the surface runoff from the continent, the thickness of the ice and its melting. The most saline parts of the MO are confined to tropical latitudes. This is the northwestern part of the Indian Ocean - the Red Sea and the Bab el Mandeb Strait (41 and 42 ‰ respectively). The salinity of the Mediterranean Sea is 39 ‰.

Natural Resources MO

A pantry of valuable chemicals, fuel, a source of energy, fresh water, food, a home for many living organisms - all this is the World Ocean. The geography of mineral resources has not been sufficiently studied at great depths, and on the shelf the development has been going on for many decades. The following natural resources of the MoD are of great value:

• Fuel (oil, gas, coal production);
• Metal and nonmetallic minerals (table salt, iron, manganese, bromine, calcium, gold, diamonds, amber, titanium, tin);
• Energy (tides, waves, hot springs);
• Building materials (sand, gravel);
• Water reserves for desalination;
• Fish, marine mammals, crustaceans, mollusks, sponges;
• Vegetable;
• Recreational.

Long since the World Ocean, the resources of the coastal zone have been used for navigation, sea fishing, cruise and beach recreation, and restoring public health. Popular beaches are located on the warm sandy coasts of the Mediterranean, the Red and Black Seas, the Atlantic, Indian, Pacific oceans in the subtropical and tropical climatic zones.

Ecological problems of the World Ocean are largely related to the growth of mining. When oil and oil products are spilled, an airtight film forms on the water surface. The exchange of oxygen and carbon dioxide between the atmosphere and the ocean is disturbed, water animals and plants die.

"Fish latitudes" of the World Ocean

Oceans and seas are areas of intensive fishing, coral and pearl mining. Seafood accounts for about 10% of food raw materials. Commercial fishes of the World Ocean are sardines, anchovies, herrings, tuna, salmon, hake, capelin, mackerel, notothenia, pollock, cod, halibut, sprat, flounder.

In those latitudes where there are conditions for the development of plankton, an abundance of fish is observed. For the reproduction of small organisms suspended in water, it is necessary that the so-called biogenic elements (nitrogen, silicon, phosphorus, calcium, etc.) rise from the bottom. Nature created similar conditions in many regions of the MoD:

• The Pacific coast of South America south of the equator;
• In the area of the Labrador Peninsula, near East Greenland in the north;
• Near the coasts of Europe and North America in the Atlantic Ocean, near 40 ° N. W .;
• From the shores of Morocco in West Africa to the extreme point in the south of the hot continent;
• Off the coast of Burma in the Indian Ocean, in the region of the islands of Indonesia.

The world ocean, as the most significant part of the continuous water envelope of the Earth, plays a huge role on the planet, and its wealth has been used by man since time immemorial. According to certain characteristics, parts of the MoD are different, but it is an integral natural complex of a planetary scale that must be preserved for the well-being of the present and future generations.