Explanation: Is this what a sonic boom looks like?
When an airplane travels at a speed faster than sound, density waves of sound emitted by the plane cannot precede the plane, and so accumulate in a cone behind the plane.
When this shock wave passes, a listener hears all at once the sound emitted over a longer period: a sonic boom.
As a plane accelerates to just break the sound barrier, however, an unusual cloud might form.
A leading theory is that a drop in air pressure at the plane described by the Prandtl-Glauert Singularity occurs so that moist air condenses there to form water droplets.
