Pressure II Segment 7: Pressure and Elevation

In the Channel 10 studio, GPS units are used for another cool pressure experiment. GPS units can display the current elevation. How? It's pressure! Since air pressure is different at different elevations (high elevation means low pressure, and vice versa), the GPS units measure air pressure to estimate elevation. Want proof? When the units are placed in airtight containers, and the pressure is changed, the elevation changes. The units are "tricked" into calculating elevations several hundred meters lower and several thousand meters higher!