Sound Propagation in Air

Estimates of meteoroid kinetic energies from observations of infrasonic airwaves

“…where E S is the bolide source energy (J), E aw the observed acoustic wave energy per unit area at the observation point (J/m 2 ); r m the density of the meteor (kg/m 3 ); Dp the observed signal overpressure (Pa); p g the ambient pressure at the ground (Pa); p S the ambient pressure at the source altitude (Pa); c S the average acoustic sound speed (m/s); V the meteor velocity (m/s); t the observed period of signal at maximum amplitude (s); e ac the acoustic efficiency; f R the ground reflection factor of Cox (1958); R 0 the slant range between source and receiver (m); R the ground projected range to source (m); R max the ducted wave skip distance, counterwind (200 km), downwind (400 km) (m). A similar detailed analytical treatment of meteor infrasound was also attempted by Golitsyn et al (1977) and recently applied to infrasonic observations of the Vitim bolide by Shumilov et al (2003).…”

Modified ray-mode (phase) theory: Understanding counter-wind propagation effects from atmospheric explosions

“…For example, we have predicted values of the mean sound speed scale height of 33.3 km (333.3 km) for an assumed vertical mean sound speed gradient= 0.01 m/s/m (0.001 m/s/m), which corresponds to size parameter values of $62.8 ( $6280) for wave frequencies of 0.10 Hz (1.0 Hz), respectively. This has of course been anticipated for a very long time (Cox, 1958), but it is reassuring that the size parameter approach also formally predicts this expected behavior as well.…”

“…14 and 15 can also be systematically compared against similar results, but without any wave frequency information, presented in Cox (1958) in his Fig. 12 for example.…”

“…In addition, acoustic shadow zone diffraction effects have also been suggested (ReVelle, 1998) with low-frequency wave penetration into acoustic shadow zones or equivalently ''zones of silence'' having frequently been observed (Cox, 1958).…”

Fireballs: Interpretation of airblast data

“…Additional references (some classical, others relatively recent) may be found in these papers. An important fundamental reference to the subject of atmospheric sound transmission is Cox (1957). The textbook by Richardson (1927) is elementary and very old but nevertheless gives an unusually clear account of early work, with numerous references.…”