The Coriolis Effect

Andrew Sorce

Understanding the Coriolis effect in terms of parcels moving North and South is fairly easy to comprehend. However, when visualizing parcels moving East and West, its hard to determine where the deflection comes from. Does anyone have a good way of explaining this deflection in East/West moving air parcels?
The lack of response only serves to reinforce my thought that a solid explanation for East West wind deflection is in indeed hard to put into words. Wikipedia seems to dance around the topic, and other searches stick to the easily explained North South wind deflection. Dig deep people, lets hear it.
OK, for a simple understandable explanation. Get a globe or a ball and a ruler. put the ruler flat on the ball/globe and roll it around the great circle (equator) of the ball/globe. The ruler goes just fine as it is flat and rotates around staying on the equator. Now move the ruler up to mid latitudes and try to roll it around east to west. You can't do it while keeping the ruler flat on the ball.