Lamb waves in a nearly isothermal atmosphere

If the variations in sound speed c (z) and wind u (z) with height z are not too great, there is a mode of propagation of acoustic waves in the atmosphere in which the wave energy E (z) decreases exponentially with z with a scale c 0 2 /(2 – y) g (about 16 km), and the phase speed c m is given approximately by (about 300 m s −1 ).