It has long been known that ocean waters cover most of the surface of our planet. They constitute a continuous water shell, which accounts for more than 70% of the entire geographical plane. But few people thought that the properties of ocean waters are unique. They have a huge impact on climatic conditions and economic activities of people.
Property 1. Temperature
Ocean waters can store heat. Surface water (about 10 cm deep) holds a huge amount of heat. Cooling, the ocean heats the lower layers of the atmosphere, due to which the average temperature of the earth's air is +15 °C. If there were no oceans on our planet, then the average temperature would hardly reach -21 ° C. It turns out that thanks to the ability of the oceans to accumulate heat, we got a comfortable and cozy planet.
Temperature properties of ocean waters change abruptly. The heated surface layer graduallyIt mixes with deeper waters, as a result of which a sharp temperature drop occurs at a depth of several meters, and then a gradual decrease to the very bottom. The deep waters of the World Ocean have approximately the same temperature, measurements below three thousand meters usually show from +2 to 0 ° С.
As for surface waters, their temperature depends on the geographic latitude. The spherical shape of the planet determines the angle of incidence of the sun's rays on the surface. Closer to the equator, the sun gives off more heat than at the poles. So, for example, the properties of the ocean waters of the Pacific Ocean directly depend on average temperature indicators. The surface layer has the highest average temperature, which is more than +19 °C. This cannot but affect the surrounding climate, and the underwater flora and fauna. This is followed by the Indian Ocean, whose surface waters are warmed up to 17.3 °C on average. Then the Atlantic, where this figure is 16.6 °C. And the lowest average temperatures are in the Arctic Ocean - about +1 °С.
Property 2. Salinity
What other properties of ocean waters are being studied by modern scientists? No doubt, they are interested in the composition of sea water. Ocean water is a cocktail of dozens of chemical elements, and s alts play an important role in it. The salinity of ocean waters is measured in ppm. Designate it with the icon "‰". Promille means a thousandth of a number. It is estimated that a liter of ocean water has an average salinity of 35‰.
When studying the oceans, scientists have repeatedly wondered what are the properties of ocean waters. Are they the same everywhere in the ocean? It turns out that salinity, like the average temperature, is not uniform. The indicator is influenced by a number of factors:
- precipitation - rain and snow significantly lower the overall salinity of the ocean;
- flow of large and small rivers - the salinity of the oceans washing the continents with a large number of full-flowing rivers is lower;
- ice formation - this process increases salinity;
- melting ice - this process lowers the salinity of the water;
- evaporation of water from the surface of the ocean - s alts do not evaporate with the waters, and salinity rises.
It turns out that the different salinity of the oceans is explained by geographic latitude, surface water temperature and climatic conditions. The highest average salinity is near the water of the Atlantic Ocean. However, the most s alty point - the Red Sea, belongs to the Indian. The Arctic Ocean is characterized by the least indicator. These properties of the oceanic waters of the Arctic Ocean are most strongly felt near the confluence of the full-flowing rivers of Siberia. Here salinity does not exceed 10‰.
Interesting fact. The total amount of s alt in the oceans
Scientists did not agree on how many chemical elements are dissolved in the waters of the oceans. Presumably from 44 to 75 elements. But they calculated that just an astronomical amount of s alts was dissolved in the World Ocean,approximately 49 quadrillion tons. If all this s alt is evaporated and dried, it will cover the surface of the land with a layer of more than 150 m.
Property 3. Density
The concept of "density" has been studied for a long time. This is the ratio of the mass of a substance, in our case, the mass of the waters of the World Ocean, to the volume occupied. Knowledge of the density value is necessary, for example, to maintain the buoyancy of ships.
Both temperature and density are heterogeneous properties of ocean waters. The average value of the latter is 1.024 g/cm³. This indicator was measured at average values of temperature and s alt content. However, in different parts of the World Ocean, the density varies depending on the depth of measurement, the temperature of the site and its salinity.
Consider, for example, the properties of the ocean waters of the Indian Ocean, and specifically the change in their density. This figure will be highest in the Suez and Persian Gulf. Here it reaches 1.03 g/cm³. In the warm and s alty waters of the northwestern Indian Ocean, the figure drops to 1.024 g/cm³. And in the freshened northeastern part of the ocean and in the Bay of Bengal, where there is a lot of precipitation, the indicator is the smallest - about 1,018 g / cm³.
The density of fresh water is lower, which is why staying afloat in rivers and other fresh water bodies is somewhat more difficult.
Properties 4 and 5. Transparency and color
If you fill a jar with sea water, it will seem transparent. However, with an increasethe thickness of the water layer, it acquires a bluish or greenish tint. The change in color is due to the absorption and scattering of light. In addition, suspensions of various compositions affect the color of ocean waters.
The bluish color of pure water is the result of weak absorption of the red part of the visible spectrum. When there is a high concentration of phytoplankton in ocean water, it becomes blue-green or green in color. This is due to the fact that phytoplankton absorbs the red part of the spectrum and reflects the green.
Transparency of ocean water indirectly depends on the amount of suspended particles in it. In the field, transparency is determined with a Secchi disk. A flat disk, the diameter of which does not exceed 40 cm, is lowered into the water. The depth at which it becomes invisible is taken as an indicator of transparency in the area.
Properties 6 and 7. Sound propagation and electrical conductivity
Sound waves can travel thousands of kilometers under water. The average propagation speed is 1500 m/s. This indicator for sea water is higher than for fresh water. The sound always deviates slightly from the straight line.
S alt water has a higher electrical conductivity than fresh water. The difference is 4000 times. It depends on the number of ions per unit of water volume.
