Left panels: forward period spacing, ΔΠ_k, in terms of the pulsation periods, Π_k, for WD models with M_⋆ = 1.29 M_⊙, T_eff ∼ 12 000 K and different thicknesses of the H envelope. Thin horizontal dashed lines correspond to the value of the asymptotic period spacing, ΔΠ^a. Right panels: oscillation kinetic energy versus the periods for the same WD models shown in the left panel. Normalization, (δr/r)_r = R⋆ = 1 (δr being the radial displacement), has been assumed to compute the kinetic energy values.