Atmospheric properties at the formation height of the Mg II k spectral line features. Intensity maps (first row, panels a–c), formation heights (second row, panels d–f), vertical velocity maps (third row, panels g–i), temperature (fourth row, panels j–l), and density (fifth row, panels m–o). We show these quantities for the following spectral features: k_2v (left column, panels a, d, g, j, and m); k₃ (middle column, panels b, e, h, k, and n); and k_2r (right column, panels c, f, i, l, and o). The synthetic spectra correspond to the snapshot muram_en_499000_379s. The pink pixels indicate where the respective spectral feature could not be detected by the peak-finding algorithm.