Sound, infrasound, and sonic boom absorption by atmospheric clouds

Abstract

This study quantifies the influence of atmospheric clouds on propagation of sound and infrasound, based on an existing model [Gubaidulin and Nigmatulin, Int. J. Multiphase Flow 26, 207-228 (2000)]. Clouds are considered as a dilute and polydisperse suspension of liquid water droplets within a mixture of dry air and water vapor, both considered as perfect gases. The model is limited to low and medium altitude clouds, with a small ice content. Four physical mechanisms are taken into account: viscoinertial effects, heat transfer, water phase changes (evaporation and condensation), and vapor diffusion. Physical properties of atmospheric clouds (altitude, thickness, water content and droplet size distribution) are collected, along with values of the thermodynamical coefficients. Different types of clouds have been selected. Quantitative evaluation shows that, for low audible and infrasound frequencies, absorption within clouds is several orders of magnitude larger than classical absorption. The importance of phase changes and vapor diffusion is outlined. Finally, numerical simulations for nonlinear propagation of sonic booms indicate that, for thick clouds, attenuation can lead to a very large decay of the boom at the ground level.

Acoustical Measurement of Natural Lightning Flashes: Reconstructions and Statistical Analysis of Energy Spectra

“…The increased spectrum decay with distance trend can be partly explained by sound absorption. At the considered frequencies (0.5 to 180 Hz), classical atmospheric absorption due to molecular relaxation of diatomic nitrogen and oxygen is negligible, but enhanced absorption by cloud droplets has been described theoretically (Baudoin et al, , their Figure 8) with absorption coefficients of the order of 1–2 dB/km in the range 10 to 100 Hz for cumulonimbus. This would explain at least partly the loss of high frequencies with distance observed in Figure .…”

Comment on “Attenuation and dispersion of sound in dilute suspensions of spherical particles” [J. Acoust. Soc. Am. 108(1), 126–146 (2000)]

“…In fact, real suspensions may be better described by particle size distributions. Nevertheless, there are few studies [10][11][12] which analyze the poly-disperse effect on sound propagation. For example, Gubadullin et al 10 showed that the assumption of mono-dispersion misjudges the absorption coefficients above the peak value near the particle resonance, Leroy et al 11 extended Foldy 13 and Henyey 14 models for poly-disperse bubble suspensions and verified it experimentally.…”

Sound propagation in saturated gas–vapor–droplet suspensions considering the effect of transpiration on droplet evaporation

“…The results of Baudoin et al [22] suggest that the assumption of monodispersion tends to overestimate the . absorption coefficient above the peak value (as observed in Fig.…”

“…Gubaidullin and Nigmatulin [24] and Bl~.udoin et al [22] investigated polydispersion effects on sound propagation, and show that it is important to take into account polydispersion. The results of Baudoin et al [22] suggest that the assumption of monodispersion tends to overestimate the .…”

“…To the author's knowledge, these are the only quantitative measurements concerning the influence of phase transformation on sound absorption in air-water droplet system (see also Baudoin et al [22]). This error'margin is smaller than the 35 percent mismatch observed between the theory and the data of Cole and Dobbins [14].…”