[aruanan]

Every now and then a poster will put up a picture that purports to be of a jet fighter breaking the sound barrier.

And most of those pictures put up have, indeed, been of a jet fighter breaking the sound barrier and not what you're referring to.

[1raider1]

If, as some have replied that the Prandtl-Glauart singularity can occur at well below trans-sonic speed, how can you say by looking at a photograph that the sound barrier is being broken?