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Coriolis_Synthesis

# Coriolis_Synthesis - Coriolis Synthesis The inertial...

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Coriolis Synthesis: The inertial circle (Free Oscillations or Inertial Oscillations) Real forces: PGF, Friction, Gravity Apparent forces: coriolis, centrifugal You will see in the literature (including Holton) a discussion of what is referred to as an “inertial circle” which is really a constant (i.e., conserved) angular momentum (L = mVr, dL/dt = 0) flow. The inertia circle is often invoked as a way to explain the Coriolis force. The reason for this is that it is a simple flow whereby all other “real” forces are presumed to vanish i.e., no pressure gradient, friction – but what about gravity (a real force)? Well, if you read Dale Durran’s 1993 BAMS article he states that: When viewed in a non-rotating reference frame (e.g., from outer space), the inertial oscillation also appears to be oscillatory. This is a clue, because if an object appears to be accelerating from a non-rotating reference frame, then it must be acted upon by a real force (it’s a non-inertial frame!). Because gravity plays a role in establishing the oscillation (as a restoring force much like a spring system, or wave clouds that undulate downstream of a mountain range), the oscillation best illustrated with a curved surface (parabolic dish) rather than a flat surface (merry-go-round) because the latter has no gravitational component in the direction opposite of the centrifugal force. But why might it be important to use a model where there is a component of gravity opposite that of the centrifugal force? Well, I’ve included a figure from Durran’s article below – with some annotation on my part – it’s really the exact same figure that is included in Holton (4 th edition, Fig. 1.6 page 13) that should help answer this question. Objects fixed on the

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