<p>The propagation and disintegration of long weakly nonlinear acoustic-gravity waves in the upper atmosphere is investigated. A direct numerical solution of the hydrodynamic equations for atmospheric gas is performed using a high-resolution model. Comparison of the results of these numerical simulations with the results of the analysis of the system of hydrodynamic equations based on the KdV–Burgers equation derived in the first part of this study for atmospheric layers showed fairly good agreement. The preferred heights near which AGWs can disintegrate approximately correspond to the heights of the change in the sign of the horizontal velocity in the wave. The parameters of small-scale secondary soliton waves formed in simulations using full hydrodynamic equations agree well with the estimates based on the analysis of the KdV–Burgers equation. The latter equation does not describe the propagation of secondary waves over time into other atmospheric layers, as well as oscillations, tilts, and deformation of the layered structure created by the primary wave, due to the approximations used in deriving the KdV–Burgers equation.</p>