NONLINEAR REFLECTION OF DIVERGENT ACOUSTIC RAREFACTION WAVES IN THE ATMOSPHERE

It is shown that the propagation velocity of a divergent rarefaction w ave in an isothermal exponential atmosphere decays to zero at a certai n critical height, which decreases as the initial pressure amplitude o f the wave increases, and at which the Mach number attains its maximum possible negative value. The latter depends only on the isentropy exp onent of the air. It is found that any further increase in the absolut e value of the Mach number in the rarefaction wave above the critical height is limited by the onset of total nonlinear reflection, which is characterized by a change of sip of the velocity of the corresponding part of the rarefaction waveform.