What environmental feature is essential for the act of soaring?

The act of soaring relies heavily on thermals, which are rising columns of warm air that provide the lift necessary for gliders and birds to ascend without mechanical power. When the sun heats the Earth's surface, it warms the air above it, causing that air to rise. Soaring practitioners utilize these thermals to gain altitude and extend their flight time while conserving energy, as it allows them to travel great distances without needing to continuously generate lift through their own propulsion.

While wind currents play a role in the overall flying experience, they are not exclusively responsible for the lift required for soaring. Weather patterns can influence soaring conditions but do not directly facilitate the act itself. Similarly, geographical terrain may provide some context for thermal formation—such as hills or valleys that can enhance rising air—but it is the thermals themselves that are the specific environmental feature essential for the propulsion of soaring. Thus, thermals are the pivotal element allowing the performance of this graceful flight technique.