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Winds and Coriolis

An important component of determing weather patterns is wind direction. If pressure differences were the only thing acting on winds, they would simply blow from high to low pressure areas. However, the Coriolis effect causes winds to appear to curve as they blow. To understand the effect, try this demonstration!

Materials Needed

  • turntable (flat circular surface like a microwave dish that can be rotated about its center).

  • a piece of cardboard, about 15 cm square
  • scissors
  • ruler
  • marker

Procedure

Cut a circle out of the cardboard the size of the turntable you use. Make a dot in the center of the circle to represent the North Pole. Place the cardboard "record" on the turntable. Using the ruler and a marker, draw a straight line from the center of the cardboard to one edge. This represents wind direction unaffected by Earth's rotation.

Slowly start the turntable rotating counterclockwise. Again, using the ruler, and marker, try to draw a straight line from the center of the cardboard to the edge. This represents winds moving from North Pole to the equator. Stop the turntable. Examine the line you have drawn.

Questions

  1. Is the first line straight?
  2. Is the second line straight?
  3. Since you drew both lines with a ruler what can you say about the wind's path?
  4. Does the wind's path really change, or does it just seem to change?
  5. Would air moving from the South Pole into the Southern Hemisphere move in the same direction?
Click here if you would like the answers to these questions.
Author: Sharron Sample
Curator: SAIC Information Services
Date: July 27, 1999