Comparison of the intensity spectra of a non-magnetic white dwarf (WD 2007−303, top) followed in order of increasing ⟨ | B | ⟩ by the DA stars WD 0446−789, WD 2105−820, WD 2047+372, WD 0257+080, and WD 2359−434. All spectra have been rebinned in bins of width 0.2 Å (in some cases two spectra have been averaged) to improve S/N in the plot, normalised to 1.0 at 6550 and 6575 Å, Doppler shifted to the rest frame of Hα, and then offset vertically for clarity.