How Big Is the Airplane That Matches the Width of an 8-Lane Roadway?

[Danger]

Looks like a .22 at around 500fps.

While I can't vouch for the speed, I can say that I've never seen a .22 rimfire bullet that looked like that. The closest that I've run across were Hornets or Yellowjackets, both of which are definitely supersonic. And I've seen very similar pictures where the bullet is clearly identifiable as a spire-point boattail hunting round.

 

[AtomBeam]

Prandtl-Glauert Clouds

U.S. Navy F/A-18F Super Hornet fighter flight demo that includes a spectacular transonic, high-speed pass (vapor cone included): http://video.google.com/videoplay?docid=6017342022780502321

Photos of transonic F/A-18 Hornet fighters with the Prandtl-Glauert Cloud: http://ChamorroBible.org/gpw/gpw-20061112.htm (via http://ChamorroBible.org/gpw/gpw-The-Spectacular-Clouds-of-the-Transonic-Flight-Regime.htm )