Wind and currents

Wind Power

The sun heats the upper layer if the world’s oceans to a depth of 20 to 30 meters. In doing so it causes the evaporation of enormous quantities of water, which escapes into the air in the form of water vapour. This transfer od heat between the ocean and atmosphere, which is really a transfer of energy*, causes the air to stir, forming winds. Winds are responsible for creating some of the currents that keep ocean water moving. The three types of ocean currents are surface currents, density-driven or thermohaline currents and slope currents.  

                                                                             

Wind Making Current

                    The action of the wind on the water’s surface creates surface currents. But these don’t move just any which way. Blowing along the equator, the trade winds create east-west current. When they reach the continents these currents run along their edges. Due to the spinning of the earth, currents that meet continents are deviated to the right in the northern hemisphere and to the left in the southern hemisphere (Carioles effect), creating the Gulf Stream in the North Atlantic and the Australian current in the pacific.

            Density-driven or thermohaline currents are deep currents driven by differences in seawater density, caused by variation in salinity and temperature. These currents are vary cold (around 0°C) and they are much slower than surface currents. It takes several centuries for them to circle the globe.

                                                     

Antarctic Ocean Circulation

                                                                 

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Step-2

In 1992, governments from around the world met in Rio de Janerio for the United Nation conference on the Environment and development. This marked the first debate on the question of how to satisfy current needs without harming those of future generations (sustainable development). The conference drafted a very thick report called the Action 21 programme; chapter 17 is devoted in its entirety to the world’s oceans, reminding us that the ocean is indispensable for life.

             The last noticeable of the three currents are the slope currents. They can be explained by the fact that the ocean’s surface is not flat but sloped 2 to 3 meters. This slope increases in the presence of atmospheric low-pressure systems. Currents are created to compensate for these differences in an attempt to make the sea level. The ocean currents and the drain in your bathtub circulate water in the same direction because of the spinning of the earth. In the northern hemisphere water swirls clockwise; in the southern hemisphere it swirls counter-clockwise!