Here's something you don't see every day: a U.S. Coast Guard C-130J soaring directly toward you, set against a backdrop of sunset-illuminated clouds. But that's not the only thing noteworthy about this photo. See the gigantic flying mustache/ Mephistophelean orbs staring deep into your soul from behind the plane? Turns out those aren't eyes at all (or a mustache); they're a dramatic instance of wake turbulence known as "wingtip vortices," captured here in absolutely breathtaking detail (click here to see it in high-res).
Wingtip vortices form on airplanes due to the finite length of their wings. In general, lift on the wings results from low-pressure, high-velocity air moving over the top of the wing and high-pressure, low-velocity air moving below the wing. Near the wingtips, the high-pressure air is able to slip around the edge to the top of the wing, generating a vortex that then trails behind the airplane.