A Mach wave (aka Mach front, Mach stem, Mach stem effect) is the constructive interference between a wave or pulsefront and its reflection, especially at a low incidence angle.
High-energy blast bombs (thermobaric, MOAB, nuclear, as opposed somewhat to neutron) can utilise the Mach wave to extend their blast-effect radius about half by judicious choice of detonation altitude.[1][2]
The Mach wave comes up in coastal engineering as a seawall-hugging surge much higher than impinging waves[3] or as an amplifier of scouring.
See also
