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October 27 2014
EAS 3 - 27
Wind Direction: parallel to isobars (lines of equal pressure)
"geostropic" means 'earth turning'
Arises from the rotation of the earth.
1) A body at rest stays at rest while a body in motion
stays in motion,
travelling at a constant speed and in a straight
line, until acted upon
by a net outside force.
2) F = ma
Vector and addition of forces
Velocity is a vector, direction and speed.
F_a + F_b = F_ab
Geostropic: Pressure gradient force + Coriolis force = 0
F_PG + F_c = 0
F_C is proportional to velocity
F_C points 90 deg to right of motion (in north hemisphere)
Occurs when at high enough altitude that surface friction
See associated images.
Pressure gradient force + Coriolis force + Ground friction
force = 0
Faster winds where isobars are closely spaced
Located above polar front, steep pressure gradients form.
Speeds up to 460 km/h have been measured.
Position of polar front is unstable
Large Rossby waves develop
Also affect location of the jet stream
Generally 3-7 around the globe at any given time