Thin Loops and curves within a contrail [Hybrid contrail, Crow Instability]

skephu

Senior Member.
This is quite an amazing video of what I think may be an example of Crow instability, but the intricate structure baffles me:

Anyone seen anything similar?
 

Mick West

Administrator
Staff member
This is quite an amazing video of what I think may be an example of Crow instability, but the intricate structure baffles me:

Anyone seen anything similar?

Which bit exactly baffles you? It looks just like a good example of a hybrid contrail with crow instabilities.
 

skephu

Senior Member.
Which bit exactly baffles you? It looks just like a good example of a hybrid contrail with crow instabilities.
Look at e.g. 0:39 or 3:25. It looks like a series of intricate knots. The usual form of the Crow instability resembles chromosome pairs, but here I see a more complex structure.



 
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Mick West

Administrator
Staff member
I think the loops pretty much always form. You just always get a sufficiently persistent hybrid contrail so you can see them. It likely requires quite precise atmospheric conditions - so as to maximize the hybrid contrail formation. More often the hybrid contrail does not extent into the connected part, so you get the "chromosome" appearance.

Here's a technical discussion of how the loops form. They are actually "vortex rings", a bit like smoke rings, formed by a kind of folding of the original vortices.

http://rs2007.limsi.fr/index.php/A_model_for_vortex_reconnection
 

M Bornong

Senior Member.
Which bit exactly baffles you? It looks just like a good example of a hybrid contrail with crow instabilities.

Isn't the thumb nail of the video a single plane formation? The opening 30 seconds implies it was made by 2 planes flying in opposite directions?
 

Mick West

Administrator
Staff member
Isn't the thumb nail of the video a single plane formation? The opening 30 seconds implies it was made by 2 planes flying in opposite directions?

The two planes are probably unrelated, or the trail just came from one of them. It looks just like a single plane hybrid contrail.
 
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