Types of Lift
Gliders, also known as sailplanes, can remain aloft for hours by utilizing the energy in the atmosphere. The sun is the ultimate cause for each of the following sources of rising air:
Thermals
Slope Soaring
Mountain Wave
Thermals are rising columns of air that are caused by uneven solar heating of the ground.
Most of the soaring conditions encountered in Texas are from thermals.
Slope soaring refers to using updrafts produced by the mechanical lifting of air as it encounters the upwind slope of a hill, ridge or mountain.
Slope soaring requires two ingredients: elevated terrain and wind.
Wave lift is created when stable air flows over a mountain or descends from the downwind side of a plateau. The air then "bounces" very high into the atmosphere.
Altitudes of more than 50,000 feet have been achieved in gliders using mountain wave and distances of more than 2,000 kilometers flown using mountain wave systems.