Includes all the seas and oceans of the Earth. It occupies about 70% of the planet's surface and contains 96% of all water on the planet. The world ocean consists of four oceans: the Pacific, Atlantic, Indian and Arctic.
Sizes of the oceans: Pacific - 179 million km2, Atlantic - 91.6 million km2, Indian - 76.2 million km2, Arctic - 14.75 million km2
The boundaries between oceans, as well as the boundaries of seas within oceans, are drawn rather arbitrarily. They are determined by land areas delimiting the water space, internal currents, differences in temperature and salinity.
Seas are divided into internal and marginal. Inland seas protrude quite deeply into the land (for example, the Mediterranean), and marginal seas adjoin the land with one edge (for example, the Northern, Japanese).
Pacific Ocean
The Pacific is the largest of the oceans. It is located in both the northern and southern hemispheres. In the east, its border is the coast of North and, in the west - the coast of and, in the south - Antarctica. It owns 20 seas and more than 10,000 islands.
As the Pacific Ocean covers all but the coldest,
it has a diverse climate. over the ocean varies from +30°
to -60° C. Trade winds form in the tropical zone; monsoons are frequent to the north, off the coast of Asia and Russia.
The main currents of the Pacific Ocean are closed in circles. In the northern hemisphere, the circle is formed by the Northern Trade Wind, North Pacific and California Currents, which are directed clockwise. In the southern hemisphere, the circle of currents is directed counterclockwise and consists of the Southern Trade Wind, East Australian, Peruvian and Western Winds.
The Pacific Ocean is located on the Pacific Ocean. Its bottom is heterogeneous; there are underground plains, mountains and ridges. On the territory of the ocean is the Mariana Trench - the deepest point of the World Ocean, its depth is 11 km 22 m.
The water temperature in the Atlantic Ocean ranges from -1 °C to + 26 °C, the average water temperature is +16 °C.
The average salinity of the Atlantic Ocean is 35%.
The organic world of the Atlantic Ocean is distinguished by a wealth of green plants and plankton.
Indian Ocean
Most of the Indian Ocean is located in warm latitudes and is dominated by humid monsoons, which determine the climate of East Asian countries. The southern edge of the Indian Ocean is sharply cold.
Indian Ocean currents change direction depending on the direction of the monsoons. The most significant currents are the Monsoon, Trade Wind and.
The Indian Ocean has a varied topography; there are several ridges, between which there are relatively deep basins. The deepest point of the Indian Ocean is the Java Trench, 7 km 709 m.
The water temperature in the Indian Ocean ranges from -1°C off the coast of Antarctica to +30°C near the equator, the average water temperature is +18°C.
The average salinity of the Indian Ocean is 35%.
Arctic Ocean
Much of the Arctic Ocean is covered in thick ice—almost 90% of the ocean surface in winter. Only near the coast does the ice freeze to the land, while most of the ice drifts. Drifting ice is called "pack".
The ocean is located entirely in northern latitudes and has a cold climate.
A number of large currents are observed in the Arctic Ocean: the Trans-Arctic Current runs along the north of Russia, and as a result of interaction with the warmer waters of the Atlantic Ocean, the Norwegian Current is born.
The relief of the Arctic Ocean is characterized by a developed shelf, especially off the coast of Eurasia.
The water under the ice always has a negative temperature: -1.5 - -1°C. In summer, the water in the seas of the Arctic Ocean reaches +5 - +7 °C. The salinity of ocean water decreases significantly in summer due to the melting of ice and, this applies to the Eurasian part of the ocean, deep Siberian rivers. So in winter the salinity in different parts is 31-34% o, in summer off the coast of Siberia it can be up to 20% o.
) or PSU (Practical Salinity Units) units of the Practical Salinity Scale.
| Element | Content, mg/l |
|---|---|
| Chlorine | 19 500 |
| Sodium | 10 833 |
| Magnesium | 1 311 |
| Sulfur | 910 |
| Calcium | 412 |
| Potassium | 390 |
| Bromine | 65 |
| Carbon | 20 |
| Strontium | 13 |
| Bor | 4,5 |
| Fluorine | 1,0 |
| Silicon | 0,5 |
| Rubidium | 0,2 |
| Nitrogen | 0,1 |
Salinity in ppm is the amount of solids in grams dissolved in 1 kg of seawater, provided that all halogens are replaced by an equivalent amount of chlorine, all carbonates are converted to oxides, organic matter burned.
In 1978, the practical salinity scale (PSS-78) was introduced and approved by all international oceanographic organizations, in which the measurement of salinity is based on electrical conductivity (conductometry), and not on water evaporation. Oceanographic CTD sounders became widely used in marine research in the 1970s, and since then salinity has been measured primarily electrically. To check the operation of electrical conductivity cells that are immersed in water, laboratory salt meters are used. In turn, standard seawater is used to check salinity meters. Standard sea water recommended international organization IAPSO for checking salinity meters, produced in the UK by the Ocean Scientific International Limited (OSIL) laboratory from natural sea water. If all measurement standards are met, a salinity measurement accuracy of up to 0.001 PSU can be obtained.
The PSS-78 scale produces numerical results similar to mass fraction measurements, and differences are noticeable either when measurements with precision better than 0.01 PSU are required or when the salt composition does not correspond to the standard composition of ocean water.
- Atlantic Ocean - 35.4 ‰ The highest salinity of surface waters in the open ocean is observed in the subtropical zone (up to 37.25 ‰), and the maximum is in the Mediterranean Sea: 39 ‰. In the equatorial zone, where the maximum amount of precipitation is recorded, salinity decreases to 34 ‰. A sharp desalination of water occurs in the estuary areas (for example, at the mouth of La Plata - 18-19 ‰).
- Indian Ocean - 34.8 ‰. The maximum salinity of surface waters is observed in the Persian Gulf and the Red Sea, where it reaches 40-41 ‰. High salinity (more than 36 ‰) is also observed in the southern tropical zone, especially in the eastern regions, and in the northern hemisphere also in the Arabian Sea. In the neighboring Bay of Bengal, due to the desalinating influence of the Ganges runoff with the Brahmaputra and Irrawaddy, the salinity is reduced to 30-34 ‰. The seasonal difference in salinity is significant only in the Antarctic and equatorial zones. In winter, desalinated waters from the northeastern part of the ocean are transported by the monsoon current, forming a tongue of low salinity along 5° N. w. In summer this language disappears.
- Pacific Ocean - 34.5 ‰. Tropical zones have the highest salinity (up to a maximum of 35.5-35.6 ‰), where intense evaporation is combined with a relatively small amount of precipitation. To the east, under the influence of cold currents, salinity decreases. High precipitation also reduces salinity, especially at the equator and in the westerly circulation zones of temperate and subpolar latitudes.
- Arctic Ocean - 32 ‰. In the Arctic Ocean there are several layers of water masses. The surface layer has a low temperature (below 0 °C) and low salinity. The latter is explained by the desalination effect of river flow, melt water and very weak evaporation. Below there is a subsurface layer, colder (up to −1.8 °C) and more saline (up to 34.3 ‰), formed when surface waters mix with the underlying intermediate water layer. The intermediate water layer is Atlantic water coming from the Greenland Sea with a positive temperature and high salinity (more than 37 ‰), spreading to a depth of 750-800 m. The deep water layer lies deeper, forming in winter time also in the Greenland Sea, slowly creeping in a single stream from the strait between Greenland and Spitsbergen. The temperature of deep waters is about −0.9 °C, salinity is close to 35 ‰. .
The salinity of ocean waters varies depending on latitude, from the open part of the ocean to the shores. In the surface waters of the oceans, it is lower in the equator region, in polar latitudes.
| Name | Salinity, ‰ |
|---|---|
How many seas are there on Earth? No one will tell you the exact answer. For example, the International Hydrographic Office identifies only 54 seas; some scientists believe that there are more than 90 seas on our planet (not counting the Caspian, Dead and Galilee, which are often classified as lakes). The most common version is that there are 81 seas. This discrepancy arises due to the fact that scientists interpret the very concept of “sea” differently.
The most common interpretation: sea - a body of water separated by parts of land or elevations of underwater relief . From a geological point of view, seas are young formations. The deepest ones were formed at the break of tectonic plates, for example, the Mediterranean. Smaller ones are formed on the outskirts of continents when continental shallows are flooded.
Characteristics of the seas
The seas actively participate in creating the temperature regime of the globe. Sea water is very lazy and heats up slowly. Therefore, for example, the water in the Mediterranean Sea becomes warmest not in July, when it is hot, but in September. As the level drops, the water cools quickly. At the bottom of the deepest seas it is about 0ºC. At the same time freeze salty water starts at -1.5 ºC; - 1.9 ºC.
Warm and cold currents move huge masses of water - warm or cold. This greatly influences climate formation.
Ebbs and flows, frequency of their changes and height also play a big role. The occurrence of high and low tides is associated with the changing phases of the Moon.
An interesting feature of sea water is known. When diving, the sea gradually “eats” the colors. At a depth of 6 m, scarlet colors disappear, at a depth of 45 m - orange, 90 m - yellow, at a depth of over 100 m only violet and greenish shades remain. Therefore, the most colorful underwater world is located at shallow depths.
Types of seas
There are several classifications that unite seas according to certain characteristics. Let's look at the most popular ones.
1. Across the oceans(list of seas by ocean)
2. By degree of isolation
Internal - do not have access to the ocean (isolated), or are connected to them through straits (semi-isolated). In fact, isolated seas (Aral, Dead) are considered to be lakes. And the straits connecting semi-isolated seas with the ocean are so narrow that they do not lead to the mixing of deep waters. Example - Baltic, Mediterranean.
Marginal - located on the shelf, have an extensive network of underwater currents and free access to the ocean. They are separated from each other by islands or underwater hills.
Interisland - such seas are surrounded by a close group of islands that prevent connection with the ocean. The largest number of such seas among the islands of the Malay Archipelago are Javanese and Sulawesi.
Intercontinental - seas lying at the junction of continents - Mediterranean, Red.
3. By water salinity There are lightly saline (Black) and highly saline (Red) seas.
4. According to the degree of ruggedness of the coastline There are seas with highly indented and slightly indented coastlines. But, for example, the Sargasso Sea has no coastline at all.
Coastlines are characterized by the presence of bays, estuaries, bays, spits, cliffs, peninsulas, beaches, fjords and capes.
The difference between a sea and a lake, a bay and an ocean
Despite the great similarity in the interpretations of the concepts “sea”, “lake”, “bay” and “ocean”, these words are not synonymous.
So, the sea differs from the lake:
Size. The sea is always bigger.
The degree of water salinity. In the sea, water is always mixed with salt, while in lakes it can be fresh, brackish or salty.
Geographical location. Lakes are always located inside continents and are surrounded on all sides by land. The seas most often have a connection with the ocean.
It is more difficult to separate seas and oceans. It's all about size here. It is generally accepted that the sea is only a part of the ocean that has unique flora and fauna. The sea may differ from the ocean in the degree of salinity of the water and the relief.
The bay is also part of the ocean, deeply cut into the land. Unlike the sea, it always has a free connection with the ocean. In some cases, the name bay is assigned to water areas, which, according to their hydrological characteristics, are more likely to belong to the seas. For example, Hudson Bay, California, Mexico.
The saltiest sea
(Dead Sea)
If we consider the Dead Sea to be a sea, and not a lake, then the palm in terms of the degree of salinity of the waters will belong to this water area. The salt concentration here is 340 g/l. Because of the salt, the density of the water is such that it is impossible to drown in the Dead Sea. By the way, this is why there are no fish or plants in the Dead Sea; only bacteria live in such a salt solution.
Of the recognized seas, the Red Sea is considered the saltiest. 1 liter of water contains 41 g of salt.
In Russia, the saltiest sea is the Barents Sea (34-37g/l).
The largest sea
(Philippine Sea)
The largest sea in the world is the Philippine Sea (5,726 thousand sq. km). Located in the western Pacific Ocean between the islands of Taiwan, Japan and the Philippines. This sea is also the deepest in the world. The greatest depth was recorded in the Mariana Trench - 11022 m. The sea territory covers 4 climatic zones at once: from equatorial to subtropical.
The largest sea in Russia is the Bering Sea (2315 thousand sq. km.)
The Pacific Ocean is the largest and oldest on our planet. It is so huge that it can easily accommodate all the continents and islands combined and that is why it is often called the Great. The area of the Pacific Ocean is 178.6 million square meters. km, which corresponds to 1/3 of the surface of the entire globe.
general characteristics
The Pacific Ocean is the most important part of the World Ocean, as it contains 53% of its total water volume. It extends from east to west for 19 thousand kilometers, and from north to south - 16 thousand. Moreover, most of its waters are located in southern latitudes, and a smaller part - in northern latitudes.
The Pacific Ocean is not only the largest, but also the deepest body of water. The maximum depth of the Pacific Ocean is 10994 m - this is exactly the depth of the famous Mariana Trench. The average figures fluctuate within 4 thousand meters.
Rice. 1. Mariana Trench.
The Pacific Ocean owes its name to the Portuguese navigator Ferdinand Magellan. During his long journey, calm and calm weather reigned across the oceanic expanses, without a single storm or storm.
The bottom topography is very diverse.
Here you can find:
- basins (Southern, Northeastern, Eastern, Central);
- deep-sea trenches (Mariana, Philippine, Peruvian;
- elevations (East Pacific Rise).
The properties of water are formed through interaction with the atmosphere and are largely subject to change. The salinity of the Pacific Ocean is 30-36.5%.
It depends on the location of the waters:
- maximum salinity (35.5-36.5%) is characteristic of waters in tropical zones, where relatively little precipitation is combined with intense evaporation;
- salinity decreases to the east under the influence of cold currents;
- salinity also decreases under the influence of heavy precipitation, this is especially noticeable at the equator.
Geographical position
The Pacific Ocean is conventionally divided into two regions - southern and northern, the border between which lies along the equator. Since the ocean is colossal in size, its boundaries are the coasts of several continents and partially bordering oceans.
In the northern part, the border between the Pacific and Arctic Oceans is the line connecting Cape Dezhnev and Cape Prince of Wales.
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Rice. 2. Cape Dezhnev.
In the east, the Pacific Ocean borders the coasts of South and North America. A little further south, the boundary between the Pacific and Atlantic Oceans extends from Cape Horn to Antarctica.
In the west, the waters of the Pacific Ocean wash Australia and Eurasia, then the border runs along the Bass Strait on the eastern side, and descends along the meridian south to Antarctica.
Climate Features
The climate of the Pacific Ocean is subject to general latitudinal zonality and the powerful seasonal influence of the Asian continent. Due to its huge area, the ocean is characterized by almost all climatic zones.
- Northeast trade winds reign in the tropical and subtropical zones of the northern hemisphere.
- The equatorial zone is characterized by calm weather throughout the year.
- In the tropics and subtropics of the southern hemisphere, the southeast trade wind dominates. In the summer, tropical hurricanes of incredible strength - typhoons - arise in the tropics.
The average air temperature in the equatorial and tropical zones is 25 Celsius. On the surface, the water temperature fluctuates between 25-30 C, while in the polar regions it drops to 0 C.
Near the equator, precipitation reaches 2000 mm, decreasing to 50 mm per year near the coast of South America.
Seas and islands
The Pacific coastline is most indented in the west, and least in the east. In the north, the Strait of Georgia cuts deeply into the mainland. The largest Pacific bays are California, Panama and Alaska.
The total area of the seas, bays and straits belonging to the Pacific Ocean occupies 18% of the total ocean area. Most of the seas are located along the coasts of Eurasia (Okhotsk, Bering, Japanese, Yellow, Philippine, East China), along the Australian coast (Solomonovo, New Guinea, Tasmanovo, Fiji, Coral). The coldest seas are located near Antarctica: Ross, Amundsen, Somov, D'Urville, Bellingshausen.
Rice. 3. Coral sea.
All rivers of the Pacific Ocean basin are relatively short, but with rapid water flow. The largest river flowing into the ocean is the Amur.
There are about 25 thousand large and small islands in the Pacific Ocean, with unique animals and flora. For the most part, they are located in equatorial, tropical and subtropical natural complexes.
The large archipelagos of the Pacific Ocean include the Hawaiian Islands, the Philippine archipelago, Indonesia, and the largest island is New Guinea.
An urgent problem in the Pacific Ocean is the significant pollution of its waters. Industrial waste, oil spills, and thoughtless destruction of ocean inhabitants can cause irreparable harm to the Pacific Ocean, upsetting the fragile balance of its ecosystem.
What have we learned?
While studying the topic "Pacific Ocean" we met with brief description ocean, its geographical location. We found out which islands, seas and rivers belong to the Pacific Ocean, what are the characteristics of its climate, and became familiar with the main environmental problems.
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