Comments on: If a weather event (Typhoon/cyclone/hurricane) circulates clockwise in the northern hemisphere,? http://hurricanequestions.com/if-a-weather-event-typhooncyclonehurricane-circulates-clockwise-in-the-northern-hemisphere.htm Wed, 23 May 2012 12:57:20 +0000 http://wordpress.org/?v=2.7.1 hourly 1 By: Chris http://hurricanequestions.com/if-a-weather-event-typhooncyclonehurricane-circulates-clockwise-in-the-northern-hemisphere.htm/comment-page-1#comment-12668 Chris Thu, 19 Aug 2010 07:05:26 +0000 http://hurricanequestions.com/if-a-weather-event-typhooncyclonehurricane-circulates-clockwise-in-the-northern-hemisphere.htm#comment-12668 The tornado itself is too small to have its rotation determined by the Coriolis effect. Like water going down plugholes or dust devils, they can spin in either direction at that size. However, the rotation of a tornado is determined by the rotation of the thunderstorm that spawns it and some thunderstorms are certainly big enough to have their rotation determined by Coriolis. This means that most tornados will spin clockwise in the southern hemisphere and anticlockwise in the north because that is the way the thunderstorms spin. To answer your question: No. The cyclone/tornado/hurricane would have to deteriorate completely before spinning the opposite direction. The tornado itself is too small to have its rotation determined by the Coriolis effect. Like water going down plugholes or dust devils, they can spin in either direction at that size.

However, the rotation of a tornado is determined by the rotation of the thunderstorm that spawns it and some thunderstorms are certainly big enough to have their rotation determined by Coriolis. This means that most tornados will spin clockwise in the southern hemisphere and anticlockwise in the north because that is the way the thunderstorms spin.

To answer your question: No. The cyclone/tornado/hurricane would have to deteriorate completely before spinning the opposite direction.

]]> By: Michel Verheughe http://hurricanequestions.com/if-a-weather-event-typhooncyclonehurricane-circulates-clockwise-in-the-northern-hemisphere.htm/comment-page-1#comment-12669 Michel Verheughe Thu, 19 Aug 2010 07:05:26 +0000 http://hurricanequestions.com/if-a-weather-event-typhooncyclonehurricane-circulates-clockwise-in-the-northern-hemisphere.htm#comment-12669 Chris gave you a very good answer about the circulation of a tornado. But you write about a larger tropical cyclone line a hurricane or typhoon, right? The point is: the air in a cyclone and the water in your sink being drained, can move straight, without spinning. But that is so unstable that it must "fall" on one side or the other. Theoretically, if you toss a coin, it can fall and rest on the edge but that is certainly most unlikely to happen, right? Well, it is the same with any fluid dynamic. A convection, turning into a tropical cyclone near the equator will be just as unstable and "fall" either in the northern or southern hemisphere and, once there, spinning counter-clockwise (in the northern) or clokwise, won't - ever - move to the other hemisphere. Just like your coin falling heads or tails, won't just move again on the other side. Chris gave you a very good answer about the circulation of a tornado. But you write about a larger tropical cyclone line a hurricane or typhoon, right?

The point is: the air in a cyclone and the water in your sink being drained, can move straight, without spinning. But that is so unstable that it must "fall" on one side or the other. Theoretically, if you toss a coin, it can fall and rest on the edge but that is certainly most unlikely to happen, right? Well, it is the same with any fluid dynamic.

A convection, turning into a tropical cyclone near the equator will be just as unstable and "fall" either in the northern or southern hemisphere and, once there, spinning counter-clockwise (in the northern) or clokwise, won’t - ever - move to the other hemisphere. Just like your coin falling heads or tails, won’t just move again on the other side.

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