Coriolis Effect
on the spinning Earth
Trajectoriesinertial reference frame
Trajectoriesrotating reference frame
Coriolis Force• Apparent force that deflects a path in the
rotating frame of reference
QuickTime™ and aH.263 decompressor
are needed to see this picture.
Coriolis Force• Trajectory is straight; observer turns
beneath it
QuickTime™ and aH.263 decompressor
are needed to see this picture.
Rotation of the Earth
• Rotates West to East(counterclockwise as seen from above North pole)
• Poles on axis; equator farthest from axis
Source: Earth and Moon Viewer,Copyright © 1989 by Jef Poskanzer.
Coriolis Force on EarthEarth rotates to the East
Source: Strahler and Strahler, Introducing Physical Geography, 2005.
Trajectories deflect right in N hemisphere
Coriolis Force on EarthWhat happens in the Southern Hemisphere?
Source: Strahler and Strahler, Introducing Physical Geography, 2005.
Trajectories deflect left in S hemisphere
Coriolis Force on Earth
• The direction toilets and bathtubs drain on earth is not determined by the Coriolis force.
• They are to small and they drain too quickly for the Coriolis force to matter.
Global Circulation
• Equatorial air rises– Moisture precipitates
– Air travels poleward
– Diverted by Coriolis effect– Sinks, warms– Converges to equator
Global Circulation
• Polar air sinks– Diverted by Coriolis effect
– Warms from ground, rises
– Moisture precipitates– Returns to poles