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Relative to the earth's surface, winds are deflected to the right in
the northern hemisphere (which could be eastward if the wind is blowing
to the north). When air moves into a deep low pressure center (like a
hurricane) it initially turns to the right as it move inward. It also
picks up speed (because of the pressure gradient) - which enhances the
Coriolis effect and the rightward turning. It will keep picking up
speed until the Coriolis force becomes so large that it offsets so much
of the pressure gradient force towards the low center that the air
motion is inward but almost circular in the counterclockwise direction.
In the southern hemisphere the Coriolis deflection is to the right -
giving an overall clockwise rotation about the low pressure center.
The pressure gradient is still inward.
Bob at PC
From: phys-l-bounces@carnot.physics.buffalo.edu
[phys-l-bounces@carnot.physics.buffalo.edu] on behalf of Anthony
Lapinski [Anthony_Lapinski@pds.org]
Sent: Wednesday, November 30, 2011 12:57 PM
To: phys-l@carnot.physics.buffalo.edu; tap-l@lists.ncsu.edu
Subject: [Phys-l] Coriolis effect
I know that the Earth spins eastward, which deflects winds to the west
(clockwise) in the northern hemisphere and to the west
(counterclockwise) in the southern hemisphere. However, hurricanes spin
counterclockwise in the northern hemisphere and clockwise in the
southern hemisphere. I don't fully comprehend this. Maybe it's more
complicated than I think. Are there other forces at work here, or am I
just missing/misunderstanding something?
Just trying to explain this in "basic" terms to kids and possibly do a
demo (e.g., using a marble and rotating turntable).
Any ideas/activities would be much appreciated.