Geography of the Earth. Water resources of the planet

Despite the fact that humanity has been paying close attention to the World Ocean for many millennia, many mysteries of the ocean remain unsolved. It is believed that to date it has been studied only ten percent. It is not surprising that the most incredible stories and myths are told about it, and the tales of the legendary Atlantis at the bottom of the ocean still excite minds.

The world ocean is a continuous, but not continuous, water shell of the planet, which includes dissolved salts and minerals carried by the rivers flowing into them from the depths of our planet. The world's oceans occupy 71% earth's surface(approximately 361 million m2), and therefore the ocean area is located on 95% of the planet’s hydrosphere. The world's oceans are extremely closely connected with the land; various substances and energy (for example, heat/cold) are constantly exchanged between them, and nature plays an important role in this interaction.

The prototype of the modern ocean, according to the generally accepted theory, is Panthalassa, which was formed on our planet about 444 million years ago and was divided into parts about 252 million years ago, when the lithospheric plates located under the continent of Pangea gradually began to move away from each other, breaking the continent into several parts.

Interestingly, many oceanographers have still not finally decided how many oceans there really are. First, scientists identified two, then three. In the middle of the last century, it was agreed that the World Ocean consists of four parts, but at the beginning of the 21st century. The International Hydrogeographical Bureau has identified the fifth, Southern, with the presence of which not everyone currently agrees.

What does the hydrosphere consist of?

Thus, the oceans known to us are parts of the World Ocean located between continents and archipelagos. They constantly exchange water masses with each other, and some currents cover as many as three oceans in a row. For example, the cold current of the Western Winds, which carries its waters not far from Antarctica, obeying the winds that blow from west to east, does not encounter large areas of land on its way, and therefore completely circles the planet, connecting the waters of the Indian, Pacific and Atlantic oceans.

Oceanographers distinguish the following oceans (they are also parts of the World Ocean):

Quiet. The largest ocean covers an area of 178.68 million km2, while the average depth of the ocean reaches almost four kilometers, and the water surface has the highest average ocean temperature - plus 19.4 ° C. Interestingly, this is where the deepest point on Earth is located - the Mariana Trench, whose depth exceeds 11 km. Here is the highest underwater mountain in the world - the Mauna Kea volcano: despite the fact that it rises 4 thousand meters above the ocean, its height from the ocean floor exceeds 10 km, being almost 2 km higher than Everest.
Atlantic. It has an elongated shape, stretches from north to south, its area is 91.66 million km2, the average ocean depth is 3.5 km, and the deepest point is the Puerto Rico Trench with a depth of more than 8.7 km. This is where the most powerful flows warm current world, the Gulf Stream, and also has one of the most mysterious and mysterious places planets, .
Indian. The area is 76.17 million km2, and the average depth exceeds 3.7 km (its deepest point is the Java Depression with a depth of more than 7.2 km).
Arctic. The area is 14.75 million km2, and the average depth is about 1.2 km, with the greatest ocean depth recorded in the Greenland Sea and slightly exceeding 5.5 km. As for the average surface water temperature, it is +1°C.
5. Southern (Antarctic). In the spring of 2000, it was decided to allocate a separate ocean in the Antarctic region between 35° south. w. (based on signs of water and atmospheric circulation) up to 60° south. w. (based on the shape of the bottom topography). Officially, its size is 20.327 million km2 - it is this area that must be subtracted from the above data of the three oceans, the Pacific, Atlantic and Indian. As for the average depth of the South, it is about 3.5 km, and the deepest place is the South Sandwich Trench - its depth is about 8.5 km.

Seas, bays and straits

The world's oceans near the coast are divided into seas, bays, and straits. The bay has a direct connection with them - a part of the ocean that does not flow deeply into the land, and always has common waters with it.

But the seas can be located at a distance of several thousand kilometers, surrounded on three sides by land, but one side is always open and connected to the ocean by straits, bays, and other seas. Seas and oceans are always connected to each other; if this connection is not there, no matter how huge the size of the body of water and no matter how salinity it has, it is considered a lake.

ocean floor

The bottom of the World Ocean is the surface of the lithospheric plate on which the waters of the World Ocean are located. The underwater bottom topography is extremely diverse: there are high mountain ranges, hills, deep gorges, trenches, valleys, and plateaus. At the same time, the ocean floor consists of several parts, connecting the deepest parts of the world's oceans with land.

The area separating the ocean shores from the water is called a sandbank (shelf), the relief of which is characterized by a common geological structure with the land. The length of the shelf bottom is about 150 meters, after which it begins a sharp descent to the continental slope, the depth of which is generally from 100 to 200 m, but can sometimes reach 1.5 km, as off the coast of New Zealand.

According to its relief and geological structure The continental slope, the length of the bottom of which is from three to four kilometers, is a continuation of the land. It is interesting that there are many underwater gorges and trenches on it, the average depth of which is about eight kilometers, and in places where the oceanic plate goes under the continental plate, it can exceed ten.

Between the continental slope and the bed there is a continental foot (though not everywhere: the largest ocean on Earth, the Pacific, does not have it in some areas). The continental base is characterized by hilly terrain and its length is about 3.5 km.

The ocean floor is located at a depth of 3.5 to 6 km. The bottom topography is characterized by deep gorges, mid-ocean ridges, hills and underwater plateaus. Most of the bottom topography consists of abyssal plains located at a depth of about five kilometers, where there are a huge number of active or extinct volcanoes.

The bottom relief of all the world's oceans is characterized by the fact that in its central part, at the junction lithospheric plates mid-ocean ridges are located. The longest underwater mountain range is the Mid-Atlantic Ridge, 20 thousand km long (it starts near the coast of Iceland and ends near Bouvet Island, which is located in the middle of Africa and Antarctica).

Since these mountains are young, constant earthquakes and volcanic eruptions are recorded in the area of the ridge, and in some places, forming islands, its peaks rise above the surface of the water.

Since the mountains are quite heavy, the ocean floor sags under them, and the relief gradually begins to drop from three to six thousand meters, turning into a deep-sea basin, the bottom of which consists of basalt and sedimentary rocks.

Flora and fauna

The nature of the ocean is amazing: its waters are home to about seventy forms from all existing forms of life on our planet, and scientists are constantly discovering new species of not only small but also large sizes. Flora presented various types algae, some of them are able to live only at the surface of the water, some - at quite great depths.

As for representatives of the fauna, the majority live in tropical and subtropical latitudes, and one of the most populated places is located off the coast of Australia. Among the inhabitants of the ocean, there are such representatives of the animal world as fish, plankton, corals, sea worms, crustaceans, cetaceans, cephalopods (squid, octopuses), and many birds live on the coast.

The nature of the Arctic and Arctic oceans is the poorest - harsh climatic conditions are to blame for this.

In the cold waters of our planet, there are more than a hundred commercial species of fish, and there are also mammals adapted for life in harsh conditions: seals, walruses, whales, and penguins, seabirds living on the coast, have perfectly adapted to the conditions of the South.

Ecology

Scientists have calculated that the annual weight of garbage dumped into the world's oceans is three times greater than the fish catch. Ocean pollution has reached the point that a real garbage continent, consisting of several hundred million tons of waste, floats in the North Pacific Ocean. most of which relates to plastic products. Plastic is dangerous because under the influence of sunlight it breaks into pieces, maintaining a polymer structure and resembling zooplankton in shape - as a result, deceived fish and jellyfish confuse it with food, swallow it, and then die.

Ocean pollution is caused by wastewater contaminated with various impurities, as well as rivers carrying pollutants such as oil, fertilizers (including insecticides and herbicides), which negatively affect the nature of the ocean and contribute to its death. Increasing accidents of tankers carrying oil, toxic and even radioactive waste cause environmental disasters, the consequences of which take many years to eliminate.

Despite the fact that various environmental organizations are trying to correct the situation, making quite incredible efforts to do this, their successes are only local: ocean pollution continues in geometric progression, and the active growth of industry suggests that in the near future a huge amount of water will enter the ocean waters. amount of harmful substances.

Let's look at the Earth from a geographical point of view. Of course, our goal is not to describe the entire Earth in geographical detail. It is completely unrealistic to do this, if only because to accommodate even the modest amount of information that we have, many hundreds of pages of text would be required. Our task is to provide generalized geographical information about our planet and provide some background information.

But first, a few words about the term “geography”. The word "geography" is known to mean "description of the Earth" or "land description". Geographical science is divided into the following main parts: physical geography, economic geography and mathematical geography.

Physical geography studies the surface of the Earth (land and ocean), relief, climate, animals and vegetable world, minerals, etc.

The area of “interest” of economic geography is clear from its name. Mathematical geography studies the shape of the Earth and its dimensions, determines the position of individual points or objects on the globe, determines the position of the globe in world space at each given moment.

One of the branches of physical geography is hydrography, which studies and describes individual water bodies: their position, size, regime and local conditions.

An area of geographical science that characterizes landforms and contains data on their size, height, extent, direction, etc. called orthography.

It must be said that these parts of geography are closely related to each other. Other sciences are also related to or adjacent to geography, such as geodesy, topography, geophysics, geology, oceanology, meteorology, etc. All these sciences are related to a certain extent, because they essentially have the same subject of study - the Earth.

Water resources planets.

If you look at the Earth from space, it will seem to us like a bluish ball that is almost completely covered with ocean. Continents are visible in the ocean, like small islands. Thus, what first catches the observer’s eye is the Earth’s water surface, i.e. that element that makes our planet unique among the planets and their satellites known to science.

Water occupies 70.8% of the globe's surface, and land only 29.2%. First let's talk about water. The globe is divided into four oceans. This division is conditional, because There are no boundaries between the oceans and cannot exist physically.

Oceans in descending order of water area:

Some scientists also highlight a fifth ocean on the map - the Southern Ocean. The waters of the Southern Ocean actually include the waters of the Pacific, Atlantic and Indian oceans in the area of the Earth's South Pole, washing Antarctica.

Deepest ocean trenches:

In the Pacific Ocean - Mariana (11022 m), Tonga (10882 m), Philippine (10265 m), Kermadec (10047 m);
- In the Atlantic Ocean - Puerto Rico (8742 m), South Sandwich (8264 m), Romanche (7856 m), Cayman (7090 m);
- In the Indian Ocean - Sunda (Javanese) (7729 m), East Indian (6335 m), Ob (5880 m):
- In the Arctic Ocean, the deepest place is in the Greenland Sea (5527 m).

The longest mountain range on Earth is the mid-oceanic chain.
It extends across all oceans for 50 thousand miles (approximately 80,465 km).

IN Pacific Ocean includes 18 seas and the Gulf of Alaska. The largest seas in area are: the Philippine (5,726,000 km 2), Coral (4,068,000 km 2) and South China (3,537,000 km 2).

TO Atlantic Ocean includes 9 seas and 4 bays. The largest in area: the Sargasso Sea (about 7 million km 2), the Weddell Sea (2.91 million km 2), the Caribbean Sea (2.77 million km 2) and the Mediterranean Sea (2.505 million km 2).

It includes 6 seas and 3 bays. The largest areas are the Arabian Sea (4.592 million km 2) and the Bay of Bengal (2.191 million km 2).

TO Arctic Ocean includes 10 seas and Hudson Bay (848 thousand km 2). The largest sea is the Barents Sea (1.424 million km2, depth up to 600 meters), and the deepest is the Greenland Sea (5527 m, area - 1.195 million km2).

There is a lot of water in the World Ocean. According to scientists, the volume of water in all four oceans of the Earth is approximately 1341 million km 3 (one billion three hundred and forty-one million cubic kilometers!). Can you imagine this volume of water? Don't worry, it's impossible to imagine. A person in his thoughts operates with cubic meters or tens of cubic meters, no more. And one cubic meter is just one billionth of a cubic kilometer. What can we say about a billion cubic kilometers!

Oceans are reservoirs of salt water that cover 70% of the Earth's surface. Life on Earth is believed to have originated in the ocean, and it continues to be home to various types of life. Oceans influence weather and temperature by absorbing solar radiation. Oceans make a huge contribution to the water cycle and are the main sources of precipitation. Although the single ocean is usually divided into several "individual" oceans, it is actually one global ocean, sometimes called the World Ocean. The area of the World Ocean is 361 million square kilometers.

The Earth's oceans are all connected to each other. Let's compare the oceans:

Pacific Ocean:

It is the largest of all oceans and separates Asia and Oceania from South America. Its area is 165,250,000 square kilometers, it borders Asia and Australia in the west and North and South America in the east. It extends from the Arctic in the north to the Antarctic Ocean in the south. Its average depth is 4,028 m, it is also the deepest ocean - depth Mariana Trench 11033 m

Atlantic Ocean:

It is the second largest ocean with an area of 106,400,000 square kilometers. Atlantic Ocean occupies an elongated, S-shaped basin between Europe and Africa in the east, North and South America in the west, it is bounded in the north by the Arctic Ocean, in the southwest Pacific Ocean, in the southeast Indian Ocean, in the south by the Antarctic Ocean. Its average depth is 3,926 m, the maximum depth is the Puerto Rico Trench 8,605 meters

Indian Ocean:

The Indian Ocean is the third largest of all oceans covering an area of 73,560,000 square kilometers. It borders on the north with the Indian and Arabian peninsulas, on the west with East Africa, in the east with Indochina, the Sunda Islands and Australia, and in the south with the Antarctic Ocean. The ocean is named after geographical location India. Its average depth is 3,963 m, the maximum depth is the Java Trench 7,724 meters

Antarctic Ocean:

The Antarctic Ocean includes the southern waters of the World Ocean. It is considered the fourth largest ocean in the world, covering an area of over 20,330,000 square kilometers. Its average depth is from 4,000 to 5,000 m, the maximum depth is in the southern part of the South Sandwich Trench 7,236 meters

Arctic Ocean:

The Arctic Ocean is the smallest and shallowest of the world's five largest oceans; its area is 8,207,654 square kilometers. It is surrounded by Eurasia and North America and is partially covered with ice throughout the year. The Arctic Ocean's temperature and salinity vary seasonally with the melting and freezing of ice sheets, and it has the lowest salinity of the five major oceans due to low evaporation, influx fresh water from rivers and streams, and the limited connection and outflow of ocean waters.

These are the main differences between Earth's oceans. We hope you found this information useful!

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