Bullet traveling through air at about 1.5 times the speed of sound.When a moving object breaks the sound barrier, a shock wave and often turbulence are created. In this image, the curved line at the nose of the bullet is a shock wave. Other shock waves can be seen alongside the bullet, and a turbulent wake trails behind it.
Credit: Andrew Davidhazy/Rochester Institute of Technology
Source: GALEX - Galaxy Evolution Explorer, link
