The majors ocean currents Superficial in the world are caused by prevailing winds. The currents can be cold, like the drift current of the west wind, or warm, like the gulf stream.
The currents circulate in trajectories called turns, moving like the hands of a clock in the northern hemisphere and on the contrary in the south.
The turn of the Earth towards the East influences the marine currents, because it tends to accumulate water against the coasts located to the west of the oceans, as when we move a container with water in one direction and the water suffers a certain delay in the movement and stands against the back wall of the container. This explains, according to some theories, that the most intense currents such as those in the Gulf in the Atlantic and Kuroshio in the Pacific are located in these areas.
This same effect of the Earth's turn would explain the areas of upwelling on the east Pacific and Atlantic coasts where cold water flows from the bottom to the surface. This phenomenon is very important from an economic point of view, because rising water draws nutrients to the surface and fishing proliferates in these areas.
In the oceans there are also, deep currents. In these the water is displaced by differences in density. Colder or more salty waters are denser and tend to sink, while somewhat warmer or less saline waters tend to rise. In this way vertical currents are generated joined by horizontal displacements to replace the moved water. In some areas the deep currents coincide with the superficial currents, while in others they go against the current.
Ocean currents transfer large amounts of heat from the equatorial to polar areas. Together with atmospheric currents, they are responsible for the fact that the thermal differences on Earth are not as strong as those that would occur on a planet without an atmosphere or hydrosphere.
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