Bernoulli invariant and its components for the field line originating at R₀ = 6 as functions of the latitudinal coordinate θ. All quantities are normalised to . The shaded grey area corresponds to the turbulent atmosphere, the end of the turbulent atmosphere coincides with the SM surfaces. The vertical lines correspond to the different critical surfaces. The vertical dashed line is the fast magneto-sonic surface while the vertical dotted line is the Alfvénic surface, consistent with the notation Fig. 8.