Albatrosses extract energy from winds to soar, as seen in these diagrammatic views from the side (left) and from overhead (right). Above a wave, winds blow progressively faster the higher you ascend. As albatrosses rise at an angle from a relatively windless wave trough, they cross a boundary into an area of brisk winds. They abruptly gain airspeed, giving them a burst of kinetic energy that allows them to climb to heights of 10 to 15 meters above the ocean. Then they bank downwind and swoop down into another wave trough, adding airspeed as they cross the boundary in reverse, and begin the cycle again.
After the birds gain height, they can proceed in any of three directions. They can turn downwind, getting a boost from the tailwind (orange). They can swoop down into the same wave trough, flying parallel to the waves and perpendicular to the wind (green). Or, like a sailboat, they can tack to the right or left of the wind and head generally into the wind (yellow). (Illustration by WHOI Graphic Services)[back]
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