General scheme of the pulsating chromosphere dynamics from Ca IR variations. Panel a: as the main shock continues to propagate outward causing a radiative wake (black arrow emitted by the green zone), Hα exhibits a blended P Cygni profile. At the same time, a blueshifted absorption appears from the emerging main shock from the κ mechanism (blue zone). This shock collides with the Ca IR infalling layers (red zone), producing a Schwarzschild profile (Sect. 6). Panel b: quiescent phase: main shock has reversed the movement of the atmosphere which is now entirely propagating outward. The Hα P Cygni profile progressively disappears around ϕ = 0.5. Panel c: following a ballistic motion, layers of the atmosphere fall onto the star (orange area). Supersonic velocities are reached if the acceleration is strong enough and thus an inverse P Cygni profile appears for Hα, Ca λ8542, and λ8662. The main shock continues to propagate outward and a Ca IR P Cygni profile could appear due to a radiative wake emission from the chromosphere (black arrow emitted by the green zone).