THE CORIOLIS EFFECT

The earth is warmest along the equator, rather than the North or South Poles, because the sun is strongest here (check out this cool site to see why). Warm air is lighter than cold air, so the warm air along the equator rises up into the atmosphere. This is called a low pressure system. 

Cold air over the poles then moves toward the equator to fill in the space as the warm air rises. This is called a high pressure system. If the earth weren't spinning, the wind would just blow from high to low pressure areas, but the earth is also spinning. This creates what is known as the Coriolis effect. The Coriolis effect causes the wind to curve as it blows. You can try this simple experiment to see the Coriolis effect for yourself.

Pearson Scott Foresman, Wikimedia Commons

You'll need a turntable or lazy susan, a piece of thin cardboard, a marker and scissors.

1. Use a drawing compass or a circular pattern (tracing a bowl works well) to cut a circle from the cardboard about the size of your lazy susan (if your lazy susan is flat on top, regular paper will work too).
2. Mark the center of the circle.
   
3. Place the cardboard circle on the lazy susan and without spinning it, draw a line from the mark at the center of the circle to the edge of your paper.
4. Now slowly spin the lazy susan counterclockwise and draw a line again from the mark at the center to the paper's edge.

How are your lines different? Your first line represents what wind would do without the Coriolis effect. Your second line represents what happens when wind blows from the North Pole toward the equator with the Coriolis effect caused by the rotation of the earth.

Because of the earth's rotation and the Coriolis effect, wind in the northern hemisphere moves in a counterclockwise motion while wind in the southern hemisphere moves in a clockwise motion.

The Coriolis effect is named for the French scientist Gaspard-Gustave de Coriolis even though he wasn't the first to recognize it.

This lesson was adapted from NASA's Earth Science Enterprise lesson "Blow, Wind, Blow!" that is no longer published.



 

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"“Blow, Wind, Blow!” El Niño Making Sense of Weather." Earth Science Enterprise. National Aeronautics and Space Administration, 22 Jan. 2003. Web. 20 Dec.                 2010. <http://kids.earth.nasa.gov/archive/nino/global.html>.
Bunglesmate. "How to Find the Center of a Circle." Instructable.com. Autodesk, Inc., 2008. Web. 8 Jan. 2016.
            <http://www.instructables.com/id/How-to-find-the-center-of-a-circle/>.
Dunbar, Brian. "What Is the Coriolis Effect?" NASA. NASA, 10 Apr. 2008. Web. 26 Apr. 2015. <http://www.nasa.gov/audience/forstudents/brainbites/nonflash                /bb_home_corioliseffect.html>.
McKissick, Katie. "What Is the Coriolis Effect?" SciJinks. NOAA and NASA, n.d. Web. 27 Sept. 2015. <http://scijinks.jpl.nasa.gov/coriolis/>.
O'Connor, J J, and E. F. Robertson. "Gaspard Gustave De Coriolis." The MacTutor History of Mathematics Archive. School of Mathematics and Statistics University             of St Andrews, Scotland, July 2000. Web. 26 Apr. 2015.
Pearson Scott Foresman. Compass3. Digital image. Wikimedia Commons. Wikimedia Foundation, 15 Dec. 2007. Web. 26 Apr. 2015.
"Seasons and Ecliptic Simulator." University of Nebraska-Lincoln. Nebraska Astronomy Applet Project/National Science Foundation, 19 Mar. 2009. Web. 8 Jan.  
             2016. <http://astro.unl.edu/naap/motion1/animations/seasons_ecliptic.swf>.
"What Is the Coriolis Effect?" ESchool Today. ESchool Today, 2010. Web. 26 Apr. 2015. <http://www.eschooltoday.com/winds/the-coriolis-effect.html>.

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This lesson was created for my hyperdoc book project for the book By the Great Horn Spoon by Sid Fleischman. Visit my Teachers Pay Teachers store for more hyperdoc book projects on other novels

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