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THE CORIOLIS EFFECT

5/2/2015

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.

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).
Mark the center of the circle.
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.
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.

"“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>.

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

WIND PATTERNS

5/2/2015

The early explorers relied solely on wind power and were able to travel around the world! Christopher Columbus sailed 5,400 miles from the Canary Islands to the Caribbean in 36 days. How was this possible? Wind.

Wind is caused by changing air pressure. The earth is divided into imaginary lines of latitude and longitude. Latitude lines go east and west around the earth parallel to the equator. The longitude lines go north and south from the north and south poles. The tilt of the earth means the sun is always most directly over the region 23 degrees north and south of the equator. This warms the air there (check out this cool site for a simulator showing this).

Since warm air is lighter than cool air, it rises up into atmosphere. As the warm air goes upward, the cool air over the north and south poles moves toward the equator and fills in the space. This movement causes wind.

Peter Mercator Wikipedia Commons

TRADE WINDS

The wind doesn't just blow in a straight line from the poles to the equator, however. There is something else affecting it, the Coriolis effect. As the earth rotates, the movement also affects the wind. The winds nearest the equator are called the trade winds. The Coriolis effect causes the trade winds to blow toward the west.

DOLDRUMS
In the area near the equator, the winds from the north and the winds from the south meet at the equator where they are warmed enough they travel upward. There are often no steady winds at the surface of the earth here. This is called the doldrums and sailors are often stuck in this area, unable to move because there is no wind.

WESTERLIES AND EASTERLIES
The area between about 30º and 60º latitude is known as prevailing westerlies because the wind comes from the west (winds are named for the direction they come from). In the area above 60º the cool air over the poles flows south and because of the Coriolis effect. It curves toward the west from the east so they are known as polar easterlies.

Make your own wind pattern map

Print a copy of the map:

printablewindpatternmap.pdf
File Size:	70 kb
File Type:	pdf

Download File

Label the equator, the tropic of Cancer, the tropic of Capricorn, the Arctic Circle and the Antarctic Circle.
Use a red crayon to draw arrows showing the trade winds.
Use a green crayon to draw arrows showing the westerlies.
Use a blue crayon to draw arrows showing the polar easterlies.
Label the doldrums and color the area yellow.
Create a key for your map.

“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>.
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>.
Mercator, Peter. December Solstice Geometry. Digital image. Wikimedia Commons. Wikimedia Foundation, 14 Dec. 2011. Web. 2 May 2015.
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>.
Wicker, Crystal. "Weather Wiz Kids Weather Information for Kids." Weather Wiz Kids Weather Information for Kids. N.p., n.d. Web. 02 May 2015.
    <http://www.weatherwizkids.com/weather-wind.htm>.

Author

I often struggle to find websites with thorough explanations in simple language to help kids understand historical events or scientific concepts, so I decided to create some of my own!

-Cookie Davis