Dynamic soaring

Dynamic soaring is a technique mostly used by birds to gain kinetic energy without effort by repeatedly crossing the boundary between air masses of different horizontal velocity. Such zones of high wind gradient can be found close to obstacles and close to the ground. Albatrosses have perfected this technique gliding just above and below in the valleys of ocean waves.

Glider pilots have been able to use this technique at meteorological wind shears at higher altitudes. This however, is very uncommon.

Note: A more detailed discription of the technique should be added here. Some gliding books also show a nice simple figure.