Ca ii  H contrast as a function of the parameters of wave motions. Upper left panel: contrast as a function of the phase shift between velocity oscillations at the bottom and upper photosphere for a period with maximum power, φ(V,V). Upper middle panel: contrast as a function of the phase shift between the temperature and velocity oscillations at the base of the photosphere, φ(T,V). Upper right panel: bi-dimensional representation of the Ca ii  H contrast as a function of φ(V,V) and φ(T,V). Bottom left panel: contrast as a function of the power of velocity oscillations. Bottom middle panel: contrast as a function of intensity oscillations, in arbitrary units. Bottom right panel: bi-dimensional representation of the Ca ii  H contrast as a function of velocity and intensity oscillation power.