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Coriolis effect: Clockwise or anticlockwise

edited August 2014 in SSC
What is the direction of spinning of hurricanes in north and south hemispheres ?

Is it clockwise in northearthen hemisphere and counter in southern hemisphere ??

Different sources mention different directions in net ... kindly clarify ..

also what is the viewing angle ? i mean if you look from top something may appear clockwise and from the back side the same thing may appear counterclockwise

Comments

  • Global winds drag on the water’s surface, causing it to move and build up in the direction that the wind is blowing. And just as the Coriolis effect deflects winds to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, it also results in the deflection of major surface ocean currents to the right in the Northern Hemisphere (in a clockwise spiral) and to the left in the Southern Hemisphere (in a counter-clockwise spiral). These major spirals of ocean-circling currents are called “gyres” and occur north and south of the equator. They do not occur at the equator, where the Coriolis effect is not present (Ross, 1995).

    Is the above bold points correct ?
  • I believe it is correct, yes.

    For hurricanes -- it's anti-clockwise in the northern hemisphere and clockwise in the southern.

    These statements are not inconsistent with each other if you remember the simple deflection rule.

    Take a mass of water, flowing as a current. In the northern hemisphere, it deflects to the right due to the Coriolis effect => clockwise currents.

    Take a depression or a low pressure area. Air moves into the spiral from higher pressure areas surrounding it.

    Consider a stream of air moving N-to-S -it's deflected to the right in the northern hemisphere. Similarly, a stream of air moving from the South to the North is deflected to its right. Think of these air currents as couples acting parallel to each other all along the circumference of the low pressure depression:

    http://upload.wikimedia.org/wikipedia/commons/e/e4/Force_and_couple.PNG

    The net effect of the couple is a cyclic anti-clockwise hurricane.

    Likewise, in the southern hemisphere, these winds ('C', in the above diagram) are deflected to the left, and the net effect is a clockwise rotating cyclone or hurricane.

    Hope that helped.
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