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Old 4th March 2008 | 13:28
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Mariner9
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Joined: Feb 2001
: PPL
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From: Worcestershire, UK
Mind you she had a Phd in Mathematics and a degree in Met, so I took it that there is none
I'd be very surprised if she hadn't heard of Gustav Gaspard de Coriolis.

Increase wind velocity, Coriolis force increases, deflecting wind to the right in the N hemisphere and to the left in the S Hemisphere.

Various formulae apply, basic one is Coriolis Force= 2 x (Angular speed of earth) x (Sin Latidude) x (Wind Velocity). Having established Coriolis force, apply this to pressure gradient force (derived from another formula), et voila!

Sod the physics though, my personal rule of thumb is that gusts of 1/4 windspeed = 10 deg veer, 1/2 windspeed = 20 deg veer, 2/3 windspeed = 30 deg veer(In N Hem.). (The same as backing factors for surface vs 2000' wind)

EG 250/20G25 is likely to be 260 in gusts, and 250/20G30 is likely to be 270 in gusts, and 250/20G35 likely to be 280 in gusts

Last edited by Mariner9; 4th March 2008 at 13:39.
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