 Another means of attaining height in a glider is exploitation of thermals, which are columns of warm rising air created by differences of temperature on the ground such as between an asphalt parking lot and a lake.Heated air rises, carrying the glider with it.As with a powered aircraft, lift is obtained by the action of the wings as the aircraft moves through the air, but in a glider, height is only gained by flying through air that is rising faster than the aircraft is sinking relative to the airflow.