What is a thermal in hang gliding?

In hang gliding, a thermal is a rising column of warm air that can be used to gain altitude. Thermals are caused by the sun heating the ground, which in turn heats the air above it. As the air rises, it expands and cools, causing it to become less dense than the surrounding air. This difference in density creates a buoyancy force that pushes the column of air upwards.

Hang gliders can use thermals to climb by circling within them. As the glider gains altitude, the pilot can then glide to another thermal or to a landing spot. To find thermals, pilots look for signs such as dust devils, birds soaring, or areas where the ground is shinier than usual. They may also use instruments such as variometers to help them locate thermals.

Ridge lift is another phenomenon that can create areas of rising air and can also be used by hang gliders for climbing.