Excellent video of vortices and aerodynamic contrails

Trailblazer

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Hope this is OK to post here - it's quite a new video and one I hadn't seen before - a really good compilation of low-altitude vortices and aerodynamic contrails on take-off and landing.

Look at 5:12 for a nice propeller contrail from a Flybe Dash 8 :)

 
Sorry, I meant the distortion of the lights and lines viewed through the vortex

Fascinating. It's the pressure gradients within the vortex bending the light. An extreme and oddly shaped version of the hot air mirage. It's exaggerated by the perspective foreshortening.
 
Sorry, I meant the distortion of the lights and lines viewed through the vortex
Oh, yeah. That's pretty cool. The refractive index of air varies according to temperature, pressure and water vapour content. I'm not sure which would be the dominant factor here though...

Edit: Mick beat me to the post. Probably pressure, then?
 
Fascinating. It's the pressure gradients within the vortex bending the light. An extreme and oddly shaped version of the hot air mirage. It's exaggerated by the perspective foreshortening.

Figured it was along those lines but the foreshortening hadn't occurred to me
 
Oh, yeah. That's pretty cool. The refractive index of air varies according to temperature, pressure and water vapour content. I'm not sure which would be the dominant factor here though...

Edit: Mick beat me to the post. Probably pressure, then?

It's really the density (mass per unit volume), which is kind of the same thing here.

Similar principle to seeing an explosion shock wave. (see various views from 2:05 here)


Figured it was along those lines but the foreshortening hadn't occurred to me
 
Plus some wingtip vortices - check out the opening shot - spot the "contrail" inside the intake of the port engine - never seen that before!! :)

 
spot the "contrail" inside the intake of the port engine - never seen that before!! :)
It makes sense though, at low speeds the air is being vigorously sucked into the engines, which would create an area of low pressure just in front of the intake blades.

And I think it's the same on both engines, just one is in shadow.
 
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