The origin of the oceans on Earth is still unknown. However, we know that salty water approximately 360 million square kilometers covers our planet. It is divided into several major oceans and smaller seas.
Oceans cover approximately 71% of the Earth's surface and 90% of its biosphere. They contain 97% of the Earth's water, and oceanographers say that only 5% of the ocean depths have been explored.
The world ocean is the main component of the Earth's hydrosphere, therefore it is an integral part of life, forms part of the carbon cycle and globally affects the climate and weather. The ocean is home to 230,000 known species animals, and perhaps more than two million underwater species, since most of them have not been studied.
I wonder, actually, how many oceans are there in the world? For many years only 4 were officially recognized, but in the spring of 2000 the International Hydrographic Organization established South ocean and set its limits.
Oceans (from Ancient Greek Ὠκεανός, Okeanos), make up most planet's hydrosphere. In descending order by area, there are:
- Quiet.
- Atlantic.
- Indian.
- Southern (Antarctic).
- Arctic Oceans (Arctic).
global ocean on earth
Although there are usually several individual oceans, a global, interconnected body of salt water is sometimes referred to as the oceans. The concept of a continuous body of water with relatively free exchange between its parts is fundamental to oceanography.
The major oceanic spaces, listed below in descending order of area and volume, are partly determined by continents, various archipelagos, and other criteria.
Oceans that exist, their location
Quiet, the largest, extends north from the Southern Ocean to the North. It spans the gap between Australia, Asia and the Americas and meets the Atlantic south of South America at Cape Horn. Pacific - separates Asia and Oceania from North and South America. Area 168,723,000 km².
Atlantic, the second largest, stretches from the Southern Ocean between America, Africa and Europe to the Arctic. He meets Indian ocean waters south of Africa at Cape Agulhas. Atlantic - separates America from Europe and Africa. Area 85,133,000 km².
Indian, the third largest, extends north from the Southern Ocean to India, between Africa and Australia. It merges into the Pacific expanses in the east, not far from Australia. Indian - washes South Asia and separates Africa and Australia. Area 70,560,000 km².
Arctic the ocean is the smallest of the five. It joins the Atlantic near Greenland and Iceland and the Pacific Ocean at the Bering Strait and overlaps North Pole touching North America in the Western Hemisphere, Scandinavia and Siberia in Eastern hemisphere. Almost all covered sea ice, the area of which varies depending on the season. Arctic - covers most of the Arctic and washes North America and Eurasia. The area is 15,000 km². They are bordered by small adjacent bodies of water, such as seas, bays and straits.
Southern- surrounds Antarctica, where the Antarctic circumpolar flow prevails. This maritime space has only recently been singled out as a separate oceanic unit, which is located south of sixty degrees south latitude and is partially covered by sea ice, whose size depends on the season. Southern - sometimes seen as an extension of the Pacific, Atlantic and Indian Oceans that surrounds Antarctica. Area 21,000 km².
Physical properties
- The total mass of the hydrosphere is about 1.4 quintillion metric tons, which is about 0.023% total mass Earth. Less than 3% - fresh water; the rest is salt water.
- The ocean area is about 361.9 million square kilometers and covers about 70.9% of the Earth's surface, and the volume of water is about 1.335 billion cubic kilometers.
- The average depth is about 3688 meters, and maximum depth is 10,994 meters in the Mariana Trench. Almost half of the world's sea waters are over 3,000 meters deep. Huge spaces depths below 200 meters cover about 66% of the Earth's surface.
- The bluish color of the water is integral part multiple facilitators. Among them are dissolved organic matter and chlorophyll. Sailors and other sailors reported that ocean waters often emit a visible glow that extends for miles at night.
oceanic zones
Oceanographers divide the ocean into different vertical zones, determined by physical and biological conditions. The pelagic zone includes all zones and can be divided into other areas, divided by depth and illumination.
The photic zone includes surfaces down to a depth of 200 m; it is an area where photosynthesis takes place and is therefore highly biodiverse.
Because plants require photosynthesis, life found deeper than the photon zone must either rely on material descending from above or find another energy source. Hydrothermal vents are the main source of energy in the so-called aphotic zone (more than 200 m deep). The pelagic part of the photon zone is known as the epipelagic.
Climate
Cold deep water rises and warms in equatorial zone, while thermal water sinks and cools near Greenland in North Atlantic and near Antarctica in the South Atlantic.
Ocean currents strongly influence the Earth's climate, transferring heat from the tropics to the polar regions. By transmitting warm or cold air and precipitation to coastal areas, winds can carry them inland.
Many of the world's goods are transported by ship between seaports peace. Ocean waters are also the main source of raw materials for the fishing industry.
However, very recently...
... in 2000, the International Hydrographic Organization united the southern parts of the Atlantic, Indian and Pacific Oceans, creating the fifth addition to the list - the Southern Ocean. And this is not a willful decision: in this region special structure currents, their own weather formation rules, etc. The arguments in favor of such a decision are as follows: in the southern part of the Atlantic, Indian and Pacific oceans, the boundaries between them are very conditional, at the same time, the waters adjacent to Antarctica have their own specifics, and are also united by the Antarctic circumpolar flow.
The largest of the oceans is the Pacific. Its area is 178.7 million km2. .
Atlantic Ocean extends over 91.6 million km 2.
The area of the Indian Ocean is 76.2 million km2.
The area of the Antarctic (Southern) Ocean is 20.327 million km 2.
Northern Arctic Ocean covers an area of approximately 14.75 million km 2.
Pacific Ocean , the largest on Earth. It was named like this famous navigator Magellan. This traveler was the first European to successfully swim across the ocean. But Magellan was just very lucky. There are often terrible storms here.
The Pacific Ocean is twice the size of the Atlantic. It occupies 165 million square meters. km, which is almost half the area of the entire oceans. It contains more than half of all the water on our planet. In one place, this ocean stretches 17 thousand km wide, stretching almost half the globe. Despite its name, this vast ocean is not only blue, beautiful and serene. Strong storms or underwater earthquakes infuriate him. Indeed, in the Pacific Ocean there are large areas seismic activity.
Photographs of the Earth from space show the true size of the Pacific Ocean. This one big ocean covers one third of the planet's surface. Its waters extend from East Asia and Africa to America. In the shallowest places, the depth of the Pacific Ocean averages 120 meters. These waters wash the so-called continental shelves, which are submerged parts of continental platforms, starting from coastline and disappearing gradually under the water. In general, the depth of the Pacific Ocean averages 4,000 meters. The depressions in the west connect to the deepest and darkest place in the world - the Mariana Trench - 11,022 m. It was previously believed that there was no life at such a depth. But even there, scientists have found living organisms!
On the Pacific Plate, a huge stretch of the earth's crust, there are ridges of high seamounts. There are many islands of volcanic origin in the Pacific Ocean, for example, Hawaii, the most large island from the archipelago Hawaiian Islands. Hawaii has the most high peak in the world - Mount Mauna Kea. She represents dormant volcano 10,000 meters high from the base at the bottom of the sea. In contrast volcanic islands there are low-lying islands formed by coral deposits that have been layered over thousands of years on the tops of underwater volcanoes. In this vast ocean, a wide variety of representatives are found. underwater world- ranging from the world's largest fish (whale shark) to flying fish, squid and sea lions. The warm shallow waters of the coral reefs are home to thousands of species of brightly colored fish and algae. All sorts of fish, marine mammals, mollusks, crustaceans and other creatures swim in the cool deep waters.
The Pacific - people and history
Sea voyages across the Pacific Ocean were undertaken as early as ancient times. About 40,000 years ago, the Aborigines crossed by canoe from New Guinea to Australia. Centuries later, between the 16th century BC. e. and X century AD. e. Polynesian tribes settled the Pacific islands, daring to overcome vast water distances. It is considered one of greatest achievements in the history of navigation. Using special canoes with a double bottom and sails woven from leaves, Polynesian navigators eventually covered almost 20 million square meters. km of ocean space. In the western Pacific, around the 12th century, the Chinese made great advances in the art of maritime navigation. They were the first to use big ships with several masts located on the underwater part of the vessel, steering, as well as compasses.
Europeans began exploring the Pacific Ocean in the 17th century, when the Dutch captain Abel Janszoon Tasman sailed around Australia on his ship and New Zealand. Captain James Cook is considered one of the most famous explorers of the Pacific Ocean. Between 1768 and 1779 he mapped New Zealand, East Coast Australia and many Pacific Islands. In 1947 Norwegian traveler Tour Heyerdahl sailed on his raft "Kon-Tiki" from the coast of Peru to the Tuamotu archipelago, which is part of French Polynesia. His expedition served as proof that the ancient native inhabitants of South America could cross vast sea distances on rafts.
In the twentieth century, the exploration of the Pacific Ocean continued. The depth of the Mariana Trench was established, and unknown species of marine animals and plants were discovered. Tourism industry development, pollution environment and the establishment of beaches threaten the natural balance of the Pacific Ocean. Governments individual countries and environmental groups are trying to minimize the damage our civilization does to the aquatic environment.
Indian Ocean
Indian Ocean is the third largest on Earth and covers 73 million square meters. km. This is the most warm ocean, whose waters are rich in various vegetation and wildlife. Most deep place in the Indian Ocean - a depression located south of the island of Java. Its depth is 7450 m. It is interesting that the currents in the Indian Ocean change their direction to the opposite twice a year. AT winter time, when monsoons prevail, the current goes to the shores of Africa, and in summer - to the shores of India.
The Indian Ocean stretches from the shores East Africa to Indonesia and Australia and from the coast of India to Antarctica. This ocean includes the Arabian and Red Seas, as well as the Bengal and Persian Gulfs. The Suez Canal connects the northern part of the Red Sea with the Mediterranean.
At the bottom of the Indian Ocean are huge sections of the earth's crust - the African Plate, the Antarctic Plate and the Indo-Australian Plate. Shifts in the earth's crust cause underwater earthquakes that cause giant waves called tsunami. As a result of earthquakes, new mountain ranges appear on the ocean floor. In some places, seamounts protrude above the surface of the water, forming most of the scattered islands in the Indian Ocean. There are deep depressions between the mountain ranges. For example, the depth of the Sunda Trench is approximately 7450 meters. The waters of the Indian Ocean are home to various representatives wildlife including corals, sharks, whales, turtles and jellyfish. Powerful currents are huge streams of water moving through the warm blue expanses of the Indian Ocean. Western australian current carries cold Antarctic waters north to the tropics.
The equatorial current, located below the equator, circulates warm waters counterclock-wise. The northern currents depend on monsoon winds that cause heavy rainfall, which change their direction depending on the season.
Indian Ocean - people and history
Seafarers and traders plowed the waters of the Indian Ocean many centuries ago. The ships of the ancient Egyptians, Phoenicians, Persians and Indians passed along the main trade routes. AT early middle ages in South East Asia settlers crossed from India and Sri Lanka. From ancient times, they swam in the Arabian Sea wooden ships called dhow, which carried exotic spices, African ivory and fabrics.
In the 15th century, the great Chinese navigator Zhen Ho led a large expedition across the Indian Ocean to the shores of India, Sri Lanka, Persia, Arabian Peninsula and Africa. In 1497, the Portuguese navigator Vasco da Gama became the first European to sail around the southern tip Africa and reached the shores of India. It was followed by English, French and Dutch traders, and the era of colonial conquest began. For centuries, new settlers, traders and pirates landed on the islands lying in the Indian Ocean. Many species of island animals that did not live anywhere else in the world became extinct. For example, the dodo, a flightless dove the size of a goose that lived in Mauritius, was exterminated by late XVII century. Giant tortoises on Rodrigues Island have disappeared XIX century. Exploration of the Indian Ocean continued into the 19th and 20th centuries. Scientists have done a great job of mapping the topography of the seabed. Currently, Earth satellites launched into orbit take pictures of the ocean, measure its depth and transmit information messages.
Atlantic Ocean
Atlantic Ocean is the second largest and covers an area equal to 82 million square meters. km. It is almost half the size of the Pacific Ocean, but its size is constantly increasing. From the island of Iceland to the south in the middle of the ocean stretches a powerful underwater ridge. Its peaks are the Azores and Ascension Island. The Mid-Atlantic Ridge - a large mountain range at the bottom of the ocean - is getting wider by about 2.5 cm annually. The deepest place in the Atlantic Ocean is a depression located north of the island of Puerto Rico. Its depth is 9218 meters. If 150 million years ago there was no Atlantic Ocean, then over the next 150 million years, scientists suggest, it will occupy more than half of the globe. The Atlantic Ocean greatly influences the climate and weather in Europe.
The Atlantic Ocean began to form 150 million years ago, when shifts in the earth's crust separated North and South America from Europe and Africa. This youngest of the oceans is named after the god Atlas, who was worshiped by the ancient Greeks.
Ancient peoples, such as the Phoenicians, began exploring the Atlantic Ocean around the 8th century BC. e. However, it was not until the ninth century A.D. e. The Vikings managed to get from the coast of Europe to Greenland and North America. Christopher Columbus, an Italian navigator who was in the service of the Spanish monarchs, began the "golden age" of the exploration of the Atlantic. In 1492, his small squadron of three ships, after a long storm, entered the Caribbean Bay. Columbus believed that he was sailing to the East Indies, but in fact he discovered the so-called New World- America. He was soon followed by other navigators from Portugal, Spain, France and England. The study of the Atlantic Ocean continues to this day. Currently, to map the relief of the seabed, scientists use an echo sounder ( sound waves). Many countries fish in the Atlantic Ocean. People have been fishing in these waters for thousands of years, but modern mining fish by trawlers has led to a significant reduction in fishing schools. The seas fringing the oceans are polluted with waste. The Atlantic Ocean keeps playing huge role in international trade. Many important trade sea routes pass through it.
Arctic Ocean
Arctic Ocean, which is located between Canada and Siberia, is the smallest and smallest compared to others. But at the same time, it is the most mysterious, as it is almost completely hidden under a huge layer of ice. The Arctic Ocean divides the Nansen Submarine Threshold into two basins. The Arctic Basin is larger in area and contains the greatest depth of the ocean. It is equal to 5000 m and is located north of Franz Josef Land. In addition, here at Russian coasts, there is an extensive continental shelf. For this reason, our Arctic seas, namely: the Kara, Barents, Laptev, Chukchi, East Siberian, are shallow.
