After yesterday’s weird cloud photograph, I remembered this one I took a few months ago. I was traveling in a car near to Heathrow Airport and saw this – it’s a sort of negative vapour trail, the plane had cleared a trail through a cloud but there was also an ordinary vapour trail close by it.
Diane's 365 photo project 
Have you ever heard anything about “chemtrails”? Don’t know if it’s real or conspiracy theory, but I’ve watched with my own eyes as a pair of jets streaked up a formation in the sky and over a course of an hour, their trails spread out and merged. Eventually, a wonderfully blue sky was covered by this grayish haze. Cloud-seeding perhaps? Your photo reminds me of what I documented in the sky above Austin about two years ago.
How very cool, a negative contrail! š