Today I've gone with this one. I took it on Canada Day in 2008. That was a great day. Hot & still. Fireflies over the marsh that night. We walked for miles and miles. Just one of those perfect days to be remembered fondly.
A lot depends on the aircraft and the conditions at the time but I would say that F-18 was very close to the speed of sound and generally when the aircraft is supersonic the shock wave moves off of the back of the wing.
I once saw a B-1b approaching Abbotsford airport on a cool August morning with an impressive cone of vapour around and it wasn't going even close to supersonic speed. High humidity likely had more to do with the vapour cone than the speed of the aircraft.