This activity models the Coriolis effect using a rotating balloon to represent Earth. Students attempt to draw straight lines from the poles toward the equator while the balloon spins, showing how Earth’s rotation makes paths appear to curve. The demonstration helps explain the deflection of winds, ocean currents, and large weather systems.

1. Inflate a balloon and mark the equator around its middle. Label the top as the North Pole and the knot as the South Pole.
2. Hold the balloon at eye level and rotate it left to right to represent Earth’s rotation.
3. One partner observes the motion from the North Pole and then the South Pole to see the apparent spin direction.
4. While one partner rotates the balloon steadily, the other attempts to draw a straight line from the North Pole to the equator.
5. Repeat the process by drawing from the South Pole to the equator.
6. Observe that the lines curve instead of being straight, demonstrating the Coriolis effect.
7. Discuss how the direction of the curve depends on the hemisphere.

Coriolis Effect Balloon - JANE DELONG:

Balloon Demonstration of Coriolis Effect - Earth Science Explained:

📄 Modeling the Coriolis Effect - Carolina: https://www.carolina.com/teacher-resources/Interactive/modeling-the-coriolis-effect/tr10643.tr?srsltid=AfmBOoqgP2rFVKs-bSE8UNuEOLOuyG7kGyGa182bCxqaUEk_9OAp1alH

• Change the balloon’s rotation speed to see how faster or slower spin affects the amount of deflection.
• Use a merry-go-round or turntable with marbles to create a larger-scale rotating system model.
• Compare the results with real-world maps of prevailing winds, hurricanes, or ocean currents.

• Handle permanent markers carefully to avoid staining clothing or skin.
• Do not overinflate balloons to prevent bursting.
• Use caution with rotating platforms like merry-go-rounds; supervise students closely.

• Why do the drawn lines curve instead of staying straight? (Because Earth’s rotation causes moving objects to appear deflected relative to the surface beneath them.)
• How does the direction of deflection differ between the northern and southern hemispheres? (Objects curve to the right in the northern hemisphere and to the left in the southern hemisphere.)
• Why does Los Angeles travel farther in a day than Anchorage, even though both complete one rotation? (Because it is at a lower latitude and moves faster due to Earth’s larger circumference there.)
• How does the Coriolis effect influence hurricanes and ocean currents? (It helps determine their rotation direction and large-scale movement patterns.)