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Paragliding by David, Alex and Abby

We live in Aspen, Colorado, and we are learning to paraglide. We know that the key to a great ride is to find thermals. Thermals are bubbles of rising air that lift the paraglider back up into the sky. Our question: Where are the strongest thermals?

What did we do?
We decided to paraglide over different kinds of terrain to find thermals. Looking out from high on a mountainside, we identified four major surface types: rocks, grass, trees and water. We used a thermal camera and looked at the different temperatures of those surface types. We then compared the images from the thermal camera to our ride results. David made three rides carrying a variometer, which is a device that tells his altitude and how quickly he is rising or falling. During his flight, he used a walkie-talkie to tell us what his altitude was and what kind of surface was underneath him. We recorded the information in a notebook.

What did we find out?
Using David's information, we constructed a graph showing his altitude during one entire ride. We also made notes about what surface he was gliding over at the time. We found that David's altitude increased slightly over grassy areas, but dropped over trees and water. His altitude went way up, about 600 feet per minute, when he was over some rocky areas. We concluded that the rocky and grassy surfaces warmed up the most in the sun, while the trees and watery areas stayed cool. When we looked out over the mountainside with the thermal camera, we confirmed that the grassy and rocky areas were the warmest, while the trees and watery areas were coolest. For their next ride, we would head for the rocky areas to find the best thermals.

What can you do?
• Look for thermals around the house. Make a little pinwheel and look for thermals over light bulbs, your toaster, even the oven vent when dinner is cooking.

• How is your house or apartment heated? Does it use hot air? Radiators? Where are the hot air vents placed and why? Can you detect warm air rising from the radiator?

• There can even be thermals in water! Try to find them in your fish's aquarium, if it has a heater.

• Use this physics investigation as a science fair project idea for your elementary or middle school science fair! Then tell us about it!

 SciLinks More on Wind Currents Go to the DFTV Boards, and tell us about your science investigation.