The total area of the World Ocean - the water shell of the Earth - 361.1 million km². This is a single system that has its own biological, chemical and physical characteristics, due to the change in which in one direction or another the ocean "lives", changes and circulates.
The oceans are water, so all of its physical and chemical features depend on changes in this environment.
Causes of ocean circulation
Water is a moving medium and in nature it is always in constant motion. The circulation of water in the ocean occurs for several reasons:
- Atmospheric circulation - wind.
- The movement of the earth around its axis.
- The effect of the gravitational force of the Moon and the Sun.
The main reason for the movement of water is the wind. It affects the water masses of the World Ocean, causes surface currents, and they, in turn, transfer this mass to different parts of the ocean. Due to internal friction, the energy of translational motion is transferred to the underlying layers, and they also begin to move.
Wind affects only the surface layer of water - up to 300 meters from the surface. And if the upper layersmove fast enough, the lower ones move slowly and depend on the bottom topography.
If we consider the World Ocean as a whole, then according to the scheme of currents, you can see that they are two large whirlpools, which are separated from each other by the equator. In the Northern Hemisphere, water moves clockwise, in the Southern Hemisphere it moves counterclockwise. At the boundaries of the continents, currents can deviate in their movement. Also, the speed of the current near the western coasts is higher than near the eastern ones.
Currents do not move in a straight line, but deviate in a certain direction: in the Northern Hemisphere - to the right, and in the Southern - in the opposite direction. This is due to the Coriolis force, which results from the rotation of the Earth around its axis.
The water in the ocean can rise and fall. This is due to the attraction of the Moon and the Sun, due to which the ebbs and flows occur. Their intensity changes over a period of time.
Thermohaline circulation of the World Ocean
"Halina" translates as "salinity". Together, the salinity and temperature of the water determine its density. Water in the World Ocean circulates, currents carry warm water from equatorial latitudes to polar latitudes - this is how warm water mixes with cold. In turn, cold currents carry water from the polar latitudes to the equatorial latitudes. This process is ongoing.
Thermohaline circulation takes place at depth, in the lower layer of currents. As a result of this process, convective movements of water occur.- cold, heavier water sinks and moves towards the tropics. Thus, surface currents move in one direction, and deep currents in the other. This is how the general circulation of the oceans occurs.
Thermohaline currents
Surface currents of the World Ocean accumulate heat at the equator, and gradually cool down when moving to high latitudes. In low latitudes, as a result of evaporation, water increases its specific gravity, its salinity increases. Reaching the polar latitudes, the water sinks, deep currents form.
There are several large currents, such as the Gulf Stream (warm), Brazilian (warm), Canary (cold), Labrador (cold) and others. Thermohaline circulation occurs according to the same pattern for all currents: both warm and cold.
Gulfstream
One of the largest warm currents on the planet is the Gulf Stream. It has a huge impact on the climate of northern and western Europe. The Gulf Stream carries its warm waters to the shores of the continent, thus determining the relatively mild climate of Europe. Further, the water cools and sinks, and the deep flow carries it to the equator.
The famous ice-free port of Murmansk is such thanks to the Gulf Stream. If we consider the fiftieth latitudes of the Northern Hemisphere, we can see that in the western part (in Canada) at this latitude there is a rather severe climate, a tundra zone passes, while in the Eastern Hemisphere, deciduous forests grow at a similar latitude. It is even possible to grow near the warm current itself.palm trees, the climate is so warm here.
The circulation dynamics of this current changes throughout the year, but the influence of the Gulf Stream is always strong.
Influence on Earth's climate
In the areas of the Weddell and Norwegian Seas, water of increased salinity comes from equatorial latitudes. At high latitudes, it cools to freezing point. When ice forms, s alt does not enter into it, as a result of which the underlying layers become more s alty and denser. This water is called North Atlantic Deep or Antarctic Bottom.
Thermohaline circulation of the World Ocean runs through a closed system.
Thus, we came to the conclusion that the greater the depth, the higher the density of water. In the ocean, lines of constant density run almost horizontally. Water with different physical and chemical properties mixes much more easily along the line of constant density than against it.
Thermohaline circulation is not well understood. It is known that this process affects not only the state of the waters of the World Ocean, but also indirectly affects the climate of the Earth. All systems on our planet are closed, so a change in some subunits leads to a change in others.
