2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/109201The system of hydrodynamic-type equations, derived by two-side distribution function for a stratified gas in gravity field is applied to a problem of ultrasound propagation and attenuation. The background state and linearized version of the obtained system is studied and compared with the Navier-Stokes one at arbitrary Knudsen numbers. The WKB solutions for ultrasound in a stratified medium are constructed in explicit form. The problem of a generation by a moving plane in a rarefied gas is explored and used as a test while compared with experiment.9 pages, 2 figuresAtmospheric and Oceanic PhysicsFluid Dynamicstext