When everything seems to be going against you, remember that the airplane takes off against the wind, not with it. ~Henry Ford
Adam Rifkin stashed this in Quotes!
Wait, is this really true? I told Emily I'd research this...
In short, pilots like to take off into a headwind because it helps them achieve "wheels up" faster. "A jetliner like a Boeing 747, needs at least 150 mph of airspeed to become airborne," says Gudmundsson. "Without wind, the plane has to accelerate to a groundspeed of 180 mph to lift off, but when you have a 30 mph headwind, the plane only has to accelerate to 150 mph, thanks to the extra boost it gets from the headwind."
Contrary to what you might have thought the last time you sat on a plane that taxied for 20 minutes, airports lay out their runways—not to drive you crazy—but to capitalize on the physics of flight. Exhibit A: In Atlanta, the main wind pattern at Hartsfield-Jackson Atlanta International Airport blows from the west, so all five of its runways are oriented from east to west.
Another factor in takeoff is air pressure, and how it changes. Wind traveling across the top of a plane’s wing moves differently than wind rushing beneath it due to the wing's aerodynamic shape. "The faster velocity of air passing over the wing creates a region of suction on the upper surface of the wing, especially toward the front," says Steve Smith, aerospace engineer at NASA's Ames Research Center. "The suction pulls the wing up."
You can see how this works by taking a strip of paper that's, say, two-inches-by-11-inches-long, and blowing lengthwise along the top of it, creating a headwind. The paper will lift up because of the pressure changes resulting from the flow of your breath, similar to what happens to a wing. But blow on it sideways, and the paper ripples wildly—a small reminder to never to fly in high crosswinds in Bilbao.