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I recently saw something I've not previously encountered: shortly after take-off, for a few seconds, an extremely dense tube of condensation rose from about 75cm in front of the wing, in-board of the engine, to a height of about 50cm above the wing and then raced back over it.

The tube of condensation was exceptionally well-defined. It appeared to have a diameter of around 15-20cm, which hardly varied, and a very circular cross-section. Its surface was smooth, and it appeared and a few seconds later disappeared as abruptly as if controlled by a switch.

As an illustration of some of the airflow over that portion of the wing, it was quite remarkable - I expected it to be more turbulent than that.

What was the likely source of this well-defined condensation? It appeared to originate from below and in front of the wing.

I've seen condensation form and travel across portions of the wing many times before, but never in this fashion, so I was thrilled to see it.

The aircraft was a 767-300 if that makes any difference.

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    $\begingroup$ @GregHewgill Not a duplicate, that's a question about how condensation forms; this one is about its point of origin. It's answered below. $\endgroup$ – Daniele Procida Jun 7 '16 at 10:07
  • $\begingroup$ If on a moist day you sit near the inlet of an MD-80, you can see a great condensation vortex going into the inlet from behind the Nose cowl, i.e. it is flowing aft to for and then does a 180 degree turn into the inlet. You can see it until ~50 knots. $\endgroup$ – OSUZorba Jun 9 '16 at 3:43
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What you might have seen is the condensation due to the vortex generated by the engine nacelle chine. The image below shows a vortex being generated by the chine.

Nacelle chine

Image from flickr.com. Photo credit- Frank Starmer

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    $\begingroup$ @aerolias That looked very much like what I saw, though what I saw recently was far thicker and denser, and better-defined. If it's coming off the leading edge of the strake/chine on the engine, that would explain a lot. I can't think of any other component around that area that would be responsible, so I will consider this the answer. The atmospheric conditions on the day must have been perfect for the formation of this vortex. Thanks! $\endgroup$ – Daniele Procida Jun 7 '16 at 8:51

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