5 years ago

Planes Landing At Stockholm's Airport Create Incredible Wake Vortices

In this interesting footage, planes from different companies and hailing from different locations on the planet all seem to leave spectacular white trails behind during landing at Stockholm Arlanda Airport on December 14, 2016. The appear as soon as the airplanes get close to the ground, showing as white tubes parallel to the ground and dissipate as soon as the plane touches down.

They are called wake or wingtip vortices, a phenomenon that appears on the tips of the wings on aircrafts during liftoff and landing. They associated with drag and are the key component of wake turbulence.

Depending on ambient atmospheric humidity, as well as the geometry and wing loading of an aircraft, water may condense or freeze in the core of these vortices, making them visible, like in this compilation of clips.

When a wing generates aerodynamic lift the air on the top surface has lower pressure relative to the bottom surface. Air flows from below the wing and out around the tip to the top of the wing in a circular fashion. An emergent circulatory flow pattern named vortex is observed, featuring a low-pressure core.

If viewed from the tail of the airplane, looking forward in the direction of flight, there is one wingtip vortex trailing from the left-hand wing and circulating clockwise, and another one trailing from the right-hand wing and circulating anti-clockwise. The result is a region of downwash behind the aircraft, between the two vortices.

The two wingtip vortices do not merge because they are circulating in opposite directions. They dissipate slowly and linger in the atmosphere long after the airplane has passed. They are a hazard to other aircraft, known as wake turbulence.

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