Time evolution of the propagating disturbance given by Eqs. (23)–(24). The continuous line represents the v_x component, while the v_z component is plotted with a dotted line. Its amplitude has been multiplied by a factor 40 for visualisation purposes. Fast and slow modes travelling to the left are denoted as F_I and S_I, F_I +  and S_I +  move to the right, and S_G is the generated wave at z = 0 (moving to the right). For this simulation z₀/a = 5, ka = 2π/0.75, v₀/v_A = 1, k_xa = 1.5 and c_s/v_A = 0.2. In this plot the time has been normalised to the characteristic time scale, τ_A = v_A/a.