Dynamic Soaring

From pbs.org:

...the concept of dynamic soaring dates back to the 1880s, when it was proposed by the physicist Lord Rayleigh. “He was watching the flight of birds and he figured out that birds could take advantage of gusts of wind,” explains Bowers. “He reasoned that as a stronger gust would hit a bird, the bird would see that as an increase in the amount of energy that it had and could convert that energy into an increase in altitude...”

Continue reading the article at pbs.org: Thermal vs. Dynamic Soaring