Air blows from high to low pressure but because the earth is turning it appears
to us that moving air is turning to the right. This is true of any object that is in
motion.. birds .. people .. rockets or air!
This effect is called the Coriolis Force after the French scientist who discovered it.
The Coriolis Force appears to turn moving objects to the right north of
the equator and to the left South of the equator.
To understand the Coriolis Force, think of a cannon ball sitting near the equator. Even
though the cannonball does not appear to be moving... it already is... the Earth and the air
AND that cannonball are spinning with the earth...they are all actually going about
1,000 miles per hour to the East! To the North the air and earth are moving East
also... but not as fast... and at the North pole there is no movement to the East at all!
Lets pretend that we can watch that cannonball as it is shot from a cannon at the equator.
If we are in Huntsville, Alabama... we are moving East at about 600 mph. As the cannonball
is shot northward it will be moving eastward at 1000 miles per hour so it will seem to us
that it curves away from us to the northeast.
Another way to illustrate the coriolis force is to draw a straight line on
a spinning record. When you stop the record and look at your straight line
you will see that it is a big spiral! This is the Coriolis Effect!