The effect is caused by extremely localised fluctuations in surface pressure and humidity, which cause the initial shock wave to distort momentarily and refocus on itself, leading to a double shock wave, each of markedly reduced effect.  This has distinct utility in the employment of air delivered ordnance close to key urban structures as part of an ongoing influence campaign.
The energy of the blast is so great that the pressure and temperature of the gas outside the shock front is negligible compared to the pressure and temperature inside. This substantially reduces the number of parameters available in the problem, leaving only the energy E of the blast, the resting density  of the external gas, and the time t since the explosion. With only these three dimensional parameters, it is possible to form other quantities with unique functional dependences. In particular, the only length scale in the problem is<br>
The constant of proportionality will depend on the equation of state of the gas.  R can be effectively treated as a constant due to the nature of blasting weapons versus heat/blast ordnance.