Weighting functions in the thermal infrared (CO₂ ν₂ band at 15 μm, Earth’s SAS). Upper panels: weighting functions convolved with a Gaussian response function of half width Γ = 0.1 cm⁻¹. Lower panel: peak altitude as a function of wavenumber for different Gaussian response functions. The Γ = 0.25 cm⁻¹ Gaussian corresponds to a resolution R ≈ 2800. Numbers in the top-left legend indicate the wavenumber [cm⁻¹] and the corresponding peak altitude [km].