Top panel: ΔN_1,tot (black solid line) as the difference between static (black dashed line for comparison) and advection cases as a function of the G₀ ∕n_H ratio for v_IF = 0.1 km s⁻¹. The blue and red dashed lines are fits of ΔN_1,tot in the weak and strong-field limit, respectively. Middle panel: ΔN_1,tot between static and advection cases as a function of v_IF. The points were obtained for a strong field of G₀∕n_H = 10². The black lines are the formula presented in Eq. (17). Bottom panel: same as middle panel but for a weak field of G₀∕n_H = 10⁻⁵. In this limit, Eq. (17) is a fit made on all the points, including metallicity, discussed in Sect. 3.4.