Lowest ocean salinity. World Ocean. Difference from fresh waters
Seventy percent of our planet's surface is covered with water - most of it in the oceans. The waters of the World Ocean are heterogeneous in composition and have a bitter-salty taste. Not every parent can answer the child’s question: “Why does sea water taste like that?” What determines the amount of salt? There are different points of view on this matter.
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What determines the salinity of water?
At different times of the year in different parts of the hydrosphere, salinity is not the same. Several factors influence its change:
- ice formation;
- evaporation;
- precipitation;
- currents;
- river flow;
- melting ice.
While water evaporates from the surface of the ocean, the salt does not erode and remains. Its concentration increases. The freezing process has a similar effect. Glaciers contain the largest supply of fresh water on the planet. The salinity of the World Ocean increases during their formation.
The opposite effect is characterized by the melting of glaciers, during which the salt content decreases. The source of salt is also rivers flowing into the ocean and precipitation. The closer to the bottom, the less salinity. Cold currents reduce salinity, warm currents increase it.
Location
According to experts, The concentration of salt in the seas depends on their location. Closer to the northern regions the concentration increases, to the south it decreases. However, in the oceans the salt concentration is always greater than in the seas, and location has no effect on this. There is no explanation for this fact.
Salinity is determined by the presence in it magnesium and sodium. One of the options for explaining the different concentrations is the presence of certain land areas enriched with deposits of such components. However, such an explanation is not very plausible if we take into account sea currents. Thanks to them, over time, the salt level should stabilize throughout the entire volume.
World Ocean
Ocean salinity depends on geographic latitude, proximity of rivers, and climatic features of objects etc. Its average value according to measurement is 35 ppm.
Near Antarctica and the Arctic in cold areas the concentration is lower, but in winter, during the formation of ice, the amount of salt increases. Therefore, the water in the Arctic Ocean is the least saline, and in the Indian Ocean the concentration of salt is the highest.
The Atlantic and Pacific oceans have approximately the same salt concentration, which decreases in the equatorial zone and, conversely, increases in tropical and subtropical regions. Some cold and warm currents balance each other. For example, the salty Labrador Current and the unsalted Gulf Stream.
Interesting to know: How many exist on Earth?
Why are the oceans salty?
There are different points of view that reveal the essence of salt in the ocean. Scientists believe that the reason is the ability of water masses to destroy rock, leaching easily soluble elements from it. This process is ongoing. Salt saturates the seas and gives them a bitter taste.
However, there is also a diametrically opposite opinion on this issue:
Volcanic activity decreased over time and the atmosphere cleared of vapors. Acid rain fell less and less, and about 500 years ago the composition of the ocean water surface stabilized and became what we know it today. Carbonates, which enter the ocean with river water, are an excellent building material for marine organisms.
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,), 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.
Since the Pacific Ocean covers almost all but the coldest,
it has a diverse climate. over the ocean varies from +30°
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 is diverse; 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, 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, a 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.
Maritime transport is the most important element of international trade. Countries such as and others, cut off from continents and not having sufficient resources of their own, are entirely dependent on. This is associated with a potential environmental hazard: the wreck of a ship carrying oil, fuel oil, coal and others causes serious damage.
Questions before a paragraph
1. What part of the Earth's surface is occupied by the World Ocean?
The oceans have a profound impact on the climate of our planet. Not only is it of great importance for the overall water cycle, but it also contains a huge reserve of minerals and is a source of food and other resources of our planet. The world's oceans occupy approximately 71% of the earth's surface. On the world map it is indicated in blue.
2. Why is our planet called Earth and not an ocean?
The fact is that once upon a time people did not know anything about the planets and sincerely believed that our Earth was flat. And here it is, the main word from which the name of our planet originates. The fact is that in the common Slavic group of languages, the root of the word Earth means the following: bottom, floor, below, soil, earth. That is, if people imagined our planet as a kind of huge pancake of land, then, accordingly, that’s what they called it, meaning: the earth below, the soil under your feet, a flat low plate.
3. Show on the map the oceans, seas, bays and straits you know.
Oceans: Pacific, Atlantic, Indian and Arctic.
Marginal seas: Norwegian, Barents, Kara, Laptev, Yellow, East Siberian, Chukchi, Bellingshausen Sea and Caribbean Sea.
Inland seas: White Sea, Sea of Azov, Black Sea.
Bays: Alaska, Bengal, Biscay, Great Australian, Guinea.
Straits: Dardanelles, Bering, Danish, English Channel, Florida, Gibraltar, Bosphorus, Dardanelles, Drake.
Questions and tasks
1. What is the average salinity of the waters of the World Ocean?
In the open ocean, salt content typically ranges from 33 to 38‰, and the average salinity of the World Ocean is 35‰. The average salinity of the ocean roughly corresponds to the salinity of a glass of water containing a teaspoon of salt.
2. Why does the salinity of the water in some seas differ greatly from the average salinity of the waters of the World Ocean?
When water evaporates from the surface of the oceans, salts remain and do not erode. As a result, their concentration increases. The freezing process has a similar effect. Glaciers contain the largest reserve of fresh water on the planet. During their formation, the salinity of the waters of the World Ocean increases. Melting glaciers have the opposite effect, reducing the salt content. In addition to them, the source of fresh water is precipitation and rivers flowing into the ocean. The level of salts also depends on the depth and nature of the currents. Their greatest concentration is on the surface. The closer to the bottom, the less salinity. Warm currents affect the salt content in a positive direction, while cold currents, on the contrary, reduce it.
3. How does the temperature of the water of the World Ocean change on the surface and at depth?
The overall temperature of the entire world's oceans averages close to 4 degrees Celsius. The water in the oceans is cold. Heating of water occurs only on the surface, and with increasing depth the temperature decreases accordingly. Temperature changes with depth unevenly. Only eight percent of the waters are warmer than ten degrees; more than half of the waters are colder by 2–3 degrees.
4. What is the main reason for the movement of sea waters?
The reasons for the appearance of currents in the world's oceans are the uneven heating of waters by the sun, as well as trade winds and monsoons - winds that blow either in one constant direction or change it depending on the time of year. Wave movements are also caused by winds, but not only. Wave movements include, for example, ebbs and flows - their cause is the attraction of the moon. Large waves (tsunamis) can be caused by earthquakes. Well, storm surges occur when sustained strong winds blow for a long time towards land.
Currents are called warm and cold, not based on their absolute temperature. If the temperature of the current waters is higher than that of the surrounding waters, then it is considered warm. If it is lower than the surrounding waters, then the current is cold.
Warm currents are directed from low to high latitudes (for example, the Gulf Stream), cold currents are directed from high to low latitudes (Labrador).
6. Based on the text of the paragraph, make a plan for describing the Arctic Ocean. Using the outline you made, describe other oceans.
1. Area and volume in the World Ocean.
2. The location of the ocean relative to the continents.
3. Connection of the ocean with other oceans.
4. Number of islands in the ocean.
The Arctic Ocean occupies 4% of the area and 1% of the volume of the World Ocean. The ocean is located in the center of the Arctic, occupying the space around the North Pole, which is located on the territory of this ocean. All its banks are southern. The Arctic Ocean is located between North America and Eurasia. It is connected to the Pacific Ocean by the Bering Strait, and to the Atlantic Ocean by a wide expanse of water between North America, the island of Greenland and the Scandinavian Peninsula of Eurasia. Part of the ocean area is occupied by marginal seas and the inland White Sea. In terms of the number of islands, the Arctic Ocean ranks second after the Pacific Ocean. All of them are located near continents. The largest islands are Greenland, Spitsbergen, Novaya Zemlya.
The Atlantic Ocean is the second largest ocean on Earth after the Pacific Ocean, located between Greenland and Iceland in the north, Europe and Africa in the east, North and South America and Antarctica in the south. The area is 91.6 million square kilometers, of which about 16% is in the seas, bays and straits. The area of coastal seas is small and does not exceed 1% of the total water area. The geographical position of the Atlantic Ocean is such that it is united with all other large bodies of water on the planet, and also washes the shores of all continents except Australia. The Atlantic Ocean is rich in both islands and archipelagos. The most significant in area: British, Greater Falklands, Iceland, Newfoundland, Greater Antilles, Bahamas, etc.
7. Explain how you understand the words of the French writer and pilot Antoine de Saint-Exupéry (novel “Planet of Humans”).
Without water, life is not possible; it is the greatest wealth. All life on planet Earth is based on the miraculous properties of water. Water is that magical substance that is found in any living organism. But if the water is salty with chemical impurities and polluted, then this is a mortal danger for all life on earth.
World Ocean is the totality of the four oceans of our planet: the Pacific, Atlantic, Indian and Arctic. The world's oceans wash the shores of all continents, but unlike land, it is a single space. The ocean occupies 71% of the surface of our planet (about 360 million km2).
The bottom of the oceans is composed of a three-layer oceanic crust. Unlike the continental crust, it has a smaller thickness - 5-10 km. In the topography of the ocean floor, it is customary to distinguish the following components: the underwater margins of continents, the transition zone, and the ocean floor.
Unlike continents, the effect of external relief-forming processes is much less pronounced in the oceans. As a result, the ocean floor is more homogeneous compared to the earth's surface.
Average ocean depths are about 3700 m, while in its open parts the smallest depths are observed in the areas of mid-ocean ridges, and the maximum are confined to deep-sea trenches.
Water masses of the World Ocean characterized by a number of properties, the main ones being temperature and salinity of water.
Ocean water temperature changes both horizontally and vertically. The water surface temperature varies zonally, decreasing in the direction from the equator to the poles. This is due to the fact that the earth's surface near the equator, due to the more vertical incidence of the sun's rays, receives more solar heat. The temperature of surface ocean waters near the equator is 25˚-28˚. In the area of the North Pole, the water surface temperature can drop to 0˚ and even slightly lower (-1.3˚), as salt water freezes at subzero temperatures.
With depth, the temperature of the waters in the World Ocean decreases due to the fact that the sun's rays are not able to heat the entire water column.
Average salinity of the world's oceans– 35%, that is, 35 g of salts are dissolved in 1 liter of ocean water. The salty taste of sea water is due to the presence of chlorides, and magnesium salts give it a bitter taste. The salinity indicator of surface waters is determined by the ratio of the amount of precipitation and the amount of evaporation. A large influx of atmospheric moisture distributes water; significant evaporation, on the contrary, increases salinity, since salts do not evaporate with water. The highest salinity of waters is characteristic of tropical latitudes, and the Red Sea is generally the saltiest sea in the world's oceans.
The waters of the World Ocean are in constant motion. The main types of water dynamics include waves (wind and tsunamis), currents, tides.
Surface currents can arise due to various reasons. In accordance with this, the types of currents are distinguished: wind (drift); with uneven distributions of temperature or salinity (density); tidal due to the attraction of the Moon; gradient when changing atmospheric pressure; stock; compensation during the ebb of the neighboring water mass, etc.
However, the main reason for the occurrence of ocean currents is the winds of the general circulation of the atmosphere: trade winds, westerly transport and others. In each of the hemispheres, the system of currents forms a kind of giant “eights”.
Based on temperature, currents are divided into warm and cold. In this case, the absolute temperature of the water does not play a role. The temperature of the current water in relation to the surrounding waters is important. That is, a warm current is a powerful stream of warmer water among colder water. The general direction of warm currents is from the equator to the poles, cold currents, on the contrary, are from the poles to the equator. Ocean currents have a significant impact on the climate of the coastal areas they wash. Thus, cold currents, preventing air from rising, help reduce precipitation. On subtropical coasts, washed by cold currents (Peruvian, Bengal), coastal deserts are formed (Atacama, Namib).
World Ocean- the place of origin of life on Earth. The living conditions for living organisms in water are more favorable compared to land. There are no sharp temperature fluctuations here; the surrounding water supports the body in space. The total number of species of living organisms in the World Ocean is approaching 160 thousand. Moreover, most of the biomass of the ocean, unlike land, is made up of animals.
The oceans are of great importance in human economic activity. The ocean is a source of natural resources. The main thing is biological resources: fish, seafood, sea animals, shells, pearls, etc. In addition to biological ones, they began to actively use mineral resources, primarily oil and gas from shelf zones. The potential energy resources are enormous. In addition, the most important transport routes serving global trade pass through the ocean. The ocean coasts are widely used for recreational purposes.
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