Thermals are by far the most prevalent of lifting sources available to the gliding pilot. They are generated by the heat of the ground radiating upwards to the air directly above.

The heated air rises in a vertical column, almost donut shaped, and eventually reaches the condensation level of the air mass, and a cloud is formed. By circling inside this rising mass of air a glider pilot can gain altitude as quickly as 1000 feet per minute.

Ridge lift is another form of rising air. In this instance a prevailing wind rushes against a long hill or ridge of hills and the air is forced upwards over the hills. If the hills are high enough, and if the run of hills is long enough, great distances can be covered by the sailplane without ever needing to circle in lift. Essentially, once the airspeed required to produce lift for the sailplane wings is produced, the excess airspeed is converted into extra height, or extra forward speed.

Mountain Wave is the third form of lift used in soaring. If a strong wind blows over a row of mountains it may set up a sine wave in the atmosphere, much like water in a river passing over a pebble. The air in a mountain wave can rise or descend as much as 2000 feet per minute, and the phenomenon can exist up to over 50,000 feet of altitude.

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