Afterburner!

Frank,

You are somehow right - it is indeed a "dump and burn". However this cannot be done without having the afterburner on (although the flame is not visible in this case). If you don't trust me try Wikipedia: "A "dump-and-burn" is a fuel dumping procedure where dumped fuel is intentionally ignited using the plane's afterburner".

The dumped fuel cannot be ignited without the flame of the afterburner flame, which in turn is ignited using special "spark plugs". Without the afterburner, the jet exhaust temperature is simply not enough to ignite the dumped fuel.
The same is valid if the jet engine afterburner gets accidentally extinguished - you'll see a white fuel plume coming out of the engine and if this happens during take off it might ruin your day.

Coming back to the picture, I did not have any remorse disqualifying some other smoke trails pictures in this challenge, but I think that the dump and burn should stay.
Best regards,

Alex