Inversions of four time steps during the development of a synthetic UF using a wavelength sampling of δλ = 55 mÅ between Δλ = ±0.55 Å in addition to points at Δλ = ±0.88 Å (case #12 from criterion B, second column in Fig. 1). Top two rows: original (solid lines with crosses) and inverted (dashed lines) Stokes I and V profiles. Second row: dotted lines illustrate the residuals from Stokes V. Bottom three rows: comparison between stratification of the simulated atmospheres (solid lines) and those inferred from the inversion of the synthetic Stokes profiles (dashed lines). Thick dashed lines correspond to the best inversion (cases with lowest χ²) and dashed lines illustrate the uncertainties.