Key features of ocean & atmosphere general circulation
Oceanic and atmospheric circulation is the means by which heat (thermal energy) is distributed on the surface of the Earth by large scale circulation of air. Atmospheric circulation, on one hand, occurs as a result of convection.
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Parts of the Earth surface near the equator receive more heat energy than any other regions near to the poles. Thus, heated low density air at the equator rises and spreads at the top of the troposphere toward the poles. The rotation of Earth, however, creates Coriolis Effect which complicates this circulation pattern of cold and warm air and hence influences atmosphere general circulation.
Latitudinal circulation features are thus influenced by the relative rotation of Earth and motion winds over the surface. High pressure winds in the northern hemisphere are deflected in a clockwise direction under the influence of Coriolis Effect. In the southern hemisphere, however, winds are deflected in a counter- clockwise direction.
Again, it is due to Coriolis Effect that the pattern of oceanic and atmospheric circulation is disintegrated into various belts referred to as Polar, Ferrel or Hardeley cells.
Longitudinal circulation features, on the other hand, are caused by disparities in temperature, which is in turn influenced by the differences in specific heat capacities of water and land. Thus, the extent of oceanic and atmospheric circulation are determined by the distribution of land and water masses
Necessary ingredients for circulation
Ocean and atmosphere general circulation are influenced by three principle forces: gravity, pressure effect and Corriolis. The effect of rotation of Earth also generates another important frictional force. Frictional force exerts an additional horizontal effect on the atmosphere near the surface of Earth.
The presence of ocean water, on the other hand, is also critical to atmosphere general circulation. Convection heat transfer also plays a significant role in atmospheric circulation process. Solar thermal energy is absorbed by liquid water in the oceans turning water into warm moist air in the atmosphere which redistributes this heat around the planet.
Importance for the climate
The atmosphere and oceans are two most crucial and indispensable water reservoirs in the hydrological cycle. The two systems work hand in hand to regulate temperature, circulation of water and influence weather and the climate.
Ocean and atmosphere circulation, the distribution of water and land masses as well as the topography of land moderates the worlds’ climate. Without all these features, the most significant climatic zones would only occur in belts parallel to the equator.
How flow in the atmospheres are consistent with relative rotation rates
The balance between pressure gradient force and gravity determines the vertical distribution of mass in the atmosphere. Gravity, however, only operates in horizontal direction and does not exert any horizontal force. The horizontal balance is created by the action of both the pressure-gradient force and Coriolis Effect, leading to a steady geostrophic flow.
As a result, steady geostrophic flow mainly occurs in the horizontal direction and is what is commonly known as general atmospheric circulation. Due to friction with the surface, rotation of the planets modifies the horizontal flow of the atmosphere below 1 kilometer altitude. This, therefore, explains how flow in the atmospheres of Venus, Earth, and Jupiter are consistent with their relative rotation rates and is attested by practical fluid experiments.