Attenuation and dispersion of acoustic energy by atmospheric dust

Insight into the role of atmospheric dust in the attenuation and dispersion of acoustic energy in the lower troposphere is gained by a comparison of theoretical attenuation coefficients and dispersion functions in the 100‐ to 107‐Hz range for the mechanisms of classical‐rotational absorption, molecular absorption, turbulent scattering, and dust absorption for a variety of dust and meterorological conditions. Over most of this frequency range the attenuation due to dust absorption is masked by one or more of the other attenuating mechanisms, but at lower frequencies there appear to be physically realizable dust and meteorological conditions wherein dust absorption may become significant. However, the most significant effect of atmospheric dust upon acoustic energy propagation lies in its dispersion, which is opposite in sign and much larger at lower frequencies than dispersion due to classical and molecular effects. The magnitudes of absorption coefficients and dispersion functions for dust are directly pr...