Beautiful swirls of fog show plane aerodynamics in action

Credit: Ruesch Productions

Flight. It happens all over the world, every day. Airplanes weighing roughly 100 tons gather thrust, take off, fly through the sky and later land in some far-flung destination. And invariably we ask "how does that work?", especially when we are young and seeing something fly for the very first time. Cue the Bill Nye music. We're diving into the mechanics of flight.

The answer, for those in a state of awe and wonder, is air pressure. Air pressure functions much like any other sort of pressure: it exerts force against things that it touches. And when something has enough pressure acting against it from a certain direction, it gets pushed, even if that push ends up coming from below. Pilots control the pressure by shaping an airplane's wings so that they make air molecules "bunch up" below them — but not on top.

Since nobody likes being all bunched up together, the air molecules exert pressure below the wing. By running air molecules into the space below the wings with engines and then bunching them up there due to the shape of the wing, sustained pressure is created.

At the same time, the shape of an airplane's wing allows for air to zip over its top. That leaves space — vacated by the air — for the wing itself to move into more easily, which we call lift.

So we've got ourselves a very basic definition of how things fly. But we haven't yet covered those awesome swirls in our video. Well, they're a function of pressure, too. Upon landing, that same upward-pressing jumble of air molecules that keep an airplane aloft gets squished between the airplane and the approaching ground — a thing appropriately called the "ground effect." By "mushing" through the ground effect (think wading through water) an airplane eventually dissipates the pressure below its wings and comes to rest.

However, all that squished-up air pressure has to go somewhere. It finds the path of least resistance out of its ever-squishing spot below the wing and shoots out from the airplane's wingtips, giving us the really cool swirls of fog in the video below.

Ruesch Productions, via Jalopnik

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