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Old 20th November 2008 | 12:14
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BOAC
Per Ardua ad Astraeus
 
Joined: Mar 2000
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From: UK
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Question...
When you say 'GF', do you mean Gradient Force? If so, my understanding was that it was not GF but Coriolis Force that deflects wind (or any moving particle) left/right (depending on southern/northern hemisphere). I understood Gradient Force as being the force which accelerates air particles from a high pressure to a low.
- assuming that was for me, Geostrophic 'force' - hence the reference to its 'effect' on cricket balls which even with your bowlers are not affected by PG (Pressure Gradient).

GF is essentially a space referenced inertia effect which manifests itself as an apparent 'force' on a rotating sphere like the earth. This makes it easier to draw a 'balance of forces' picture.
the forces balance out and the air particles/wind being to travel parallel to curved isobars. Is this correct?
- no - parallel to straight isobars as per my previous. Curving the isobars and 'requiring' the wind to flow 'around' a curved system now requires an extra force (centripetal) to effect the curve [cf a cricket ball being swung around on a piece of string (don't tell your bowlers)]. The resulting 'balance of forces' results in a final direction which is not quite 'parallel' to the isobars (or 'tangential') hence the statement that the only 'true' G wind occurs with straight isobars.
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