Just a pressure wave (below speed of sound). There might be a shock wave too (faster than sound) within the expansion of the fireball but the wave of fog after it is condensing water vapor in pressurised cold air. Same phenomenon that can be seen sometimes at the wings of (subsonic) airplanes.
Wow, two shock waves
It’s looped for some silly reason
Just a pressure wave (below speed of sound). There might be a shock wave too (faster than sound) within the expansion of the fireball but the wave of fog after it is condensing water vapor in pressurised cold air. Same phenomenon that can be seen sometimes at the wings of (subsonic) airplanes.