The total area of the World Ocean - the water shell of the Earth - 361.1 million km². This is a single system, which has its own biological, chemical and physical features, due to which the ocean “lives”, changes and circulates due to its change in one direction or another.
The oceans are water, therefore, all its physical and chemical features depend on changes in this environment.
Reasons for the circulation of water in the ocean
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 gravity of the moon and the sun.
The main reason for the movement of water is the wind. It acts on the water masses of the oceans, causes surface currents, and they, in turn, carry this mass to different parts of the ocean. Due to internal friction, the energy of the 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 layers move fast enough, then the lower ones move slowly and depend on the topography of the bottom.
If we consider the oceans as a whole, then according to the pattern of currents, you can see that they are two large maelstroms that are separated by an equator. In the Northern Hemisphere, water moves clockwise, in the Southern Hemisphere - against. At the borders of continents, currents can deviate in their movement. Also, the current velocity near the western shores is higher than near the eastern ones.
The 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 occurs as a result of the rotation of the Earth around its axis.
Water in the ocean can rise and fall. This is due to the attraction of the moon and the sun, due to which there are ebbs and flows. Their intensity changes over a period of time.
Thermohaline circulation of the oceans
"Halina" is translated as "salinity." Together, salinity and water temperature determine its density. Water in the oceans circulates, currents transfer warm water from equatorial latitudes to polar - so warm water mixes with cold. In turn, cold currents transfer water from polar latitudes to equatorial. This process is ongoing.
Thermohaline circulation occurs at a depth in the lower layer of currents. As a result of this process, convective water movements occur - cold, heavier water sinks and moves toward the tropics. Thus, surface currents move in one direction, and deep flows in the other. So the general circulation of the oceans takes place.
Thermohaline currents
The surface currents of the oceans accumulate heat at the equator, and when moving to high latitudes they gradually cool down. At low latitudes as a result of evaporation, water increases its specific gravity, its salinity increases. Reaching polar latitudes, water sinks, deep currents form.
There are several large currents, for example, the Gulf Stream (warm), Brazilian (warm), Canary (cold), Labrador (cold) and others. Thermohaline circulation occurs according to one scheme 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, thereby determining the relatively mild climate of Europe. Further, the water cools and falls, 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 fifties latitudes of the Northern Hemisphere, we can see that in the western part (in Canada) at this latitude there is a rather severe climate, the tundra zone passes, in the Eastern hemisphere deciduous forests grow at a similar latitude. Along with the warmest flow, even palm growing is possible, 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 great.
