Re: planetary and atmospheric rotation - origins, direction, etc

On 2008-02-29, Wayne Throop <throopw@xxxxxxxxx> wrote:
If you interpose a completely frictionless membrane along the
ground, to isolate the air from any lateral influence from the
ground, it'd still experience coriolis forces.

Only if it was still spinning. Without any coupling with the ground,
it would have no reason to spin at the same rate, and would long ago
have ceased spinning.


Indeed, even if you meant that the atmosphere was motionless in an
inertial frame, and you were using coordinates where the ground is
motionless, the atmosphere would *still* be subject to the coriolis
effect;

That is what I meant, but I disagree with your conclusion. It would
be subject to coriolis (pseudo)forces, but not to the coriolis
*effect*.


The coriolis force on an object moving antispinward is equal and
opposite to the centrifugal force on an object at that distance from
the center.

In the rotating reference frame for the situation under discussion,
the coriolis force has twice the magnitude of the centrifugal force.

|Centrifugal| = w^2 |r|
|Coriolis| = |2 w x v| = 2 |w| |v| = 2 w^2 |r|

In the rotating reference frame the excess coriolis force acts
centripetally, keeping the object in uniform circular motion.


- Tim
.

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