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In meteorology, air currents are concentrated areas of winds. They are mainly due to differences in atmospheric pressure or temperature . They are divided into horizontal and vertical currents; both are present at mesoscale while horizontal ones dominate at synoptic scale .
A Wind generated current is a flow in a body of water that is generated by wind friction on its surface. Wind can generate surface currents on water bodies of any size. The depth and strength of the current depend on the wind strength and duration, and on friction and viscosity losses, [1] but are limited to about 400 m depth by the mechanism, and to lesser depths where the water is shallower. [2]
Knowing the wind sampling average is important, as the value of a one-minute sustained wind is typically 14% greater than a ten-minute sustained wind. [16] A short burst of high speed wind is termed a wind gust ; one technical definition of a wind gust is: the maxima that exceed the lowest wind speed measured during a ten-minute time interval ...
The largest ocean current is the Antarctic Circumpolar Current (ACC), a wind-driven current which flows clockwise uninterrupted around Antarctica. The ACC connects all the ocean basins together, and also provides a link between the atmosphere and the deep ocean due to the way water upwells and downwells on either side of it.
In the study of fluid mechanics, researchers attempt to give a correct explanation of marine currents.Currents are caused by external driving forces such as wind, gravitational effects, coriolis forces and physical differences between various water masses, the main parameter being the difference of density that varies in function of the temperature and salinity.
The wind blowing parallel to a water surface deforms that surface as a result of shear action caused by the fast wind blowing over the stagnant water. The wind blowing over the surface applies a shear force on the surface. The wind stress is the component of this force that acts parallel to the surface per unit area.
Due to the Coriolis effect, surface water moves at a 90° angle to the wind current. If the wind moves in a direction causing the water to be pulled away from the coast then Ekman suction will occur. [1] On the other hand, if the wind is moving in such a way that surface waters move towards the shoreline then Ekman pumping will take place. [1]
Hence from the point of view of the atmosphere, the ocean can be considered effectively stationary; from the point of view of the ocean, the atmosphere imposes a significant wind stress on its surface, and this forces large-scale currents in the ocean. Through the wind stress, the wind generates ocean surface waves; the longer waves have a ...