Mid-transit velocity shift of the dominant (red) component in the helium 1083 nm triplet as a function of the night-to-day side pressure ratio. The data points represent the average velocity shift over five snapshots in the steady-state, with error bars indicating the corresponding standard deviation. All models show the same trend: the line becomes more blueshifted with increasing day-night anisotropy. However, for ratios <50%, this behavior shifts, due to the occurrence of incident material on the night side. A represents the fiducial model group, including A′, with the distinction that the latter employs a constant ṁ_p instead of a constant ρ_p as outlined in Sect. 3.3 (see full model overview in Table 1).