## Coriolis effect

Wind action on the surface does not simply blow the water in the same direction as the wind, except in very shallow depths. The earth's rotation causes a deflecting effect so that surface water is moved at an angle to the wind. This deflection, generally known as the Coriolis effect after the French engineer and mathematician who first derived an equation for it, influences any object moving on the earth's surface, and is due to the rotational movement of the earth beneath the moving body. In most cases the effect is so small compared with other forces

Figure 1.5 Major tectonic plate boundaries. Arrows indicate relative directions of movement. Submarine ridges develop at separating boundaries; ocean trenches or new mountains at colliding boundaries. Dotted lines indicate uncertain plate boundaries.

involved that it can be ignored, but in movements of the atmosphere and oceans the Coriolis effect has a magnitude comparable with the forces producing the motion, and must certainly be taken into account in understanding the course of ocean currents (Ingmanson and Wallace, 1995).

The Coriolis effect is equivalent to a force acting at 90° to the direction of movement, tending to produce a right-handed or clockwise deflection in the northern hemisphere and a left-handed or counterclockwise deflection in the southern hemisphere. It is proportional to the speed of movement and to the sine of latitude, being zero at the Equator. The Coriolis deflecting force, F, acting on a body of mass m moving with velocity V in latitude \$ can be expressed

F = 2cV sin co being the angular rate of rotation of the earth.

Thus the Coriolis deflection acts to the right of wind direction north of the Equator and to the left south of the Equator. Theoretically, in deep water of uniform density it results in a deflection of 45° to wind direction at the surface. This deflection increases with depth. The speed of the wind-generated current decreases logarithmically with depth and becomes almost zero at the depth at which its direction is opposite to the surface movement. The deflecting effect is less in shallow or turbulent water. A sharp temperature gradient near the surface has an effect similar to a shallow bottom. The warmer surface layer tends to slide over the colder water below, following wind direction more closely than it would if the temperature were uniform throughout the water column.

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## Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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### Responses

• sirkka myllyniemi
Does coriolis effect set ocean currents in motion?
9 years ago
• Michael Massawa
What is coriolis effect ecology?
8 years ago