How does a glider fly?

The shape of a glider wing is an airfoil. This gives the wing lift. But a glider will fall to earth unless the pilot finds thermals to keep the glider up.

Thermals are warm currents of rising air. They are created when the sun shines on land, such as bare rock, that reflects heat. As the heated air rises, the glider can ride on the updrafts and stay up for hours.