Comparison of the temperature stratification with optical depth for the different penumbral atmospheres indicated in Fig. 3. Left panel: temperature stratification of six different models corresponding to the six different pixels in the penumbra of the sunspot as a function of optical depth. The model with the lowest uncertainty from Socas-Navarro (2007), is also shown for the sake of comparison. Contribution functions computed from the cool penumbral model for the Mg II k_2v, Ca II 8542 core, and Ca II wing-averaged over the wavelength range between 8541.15 Å and 8542.28 Å, are plotted (in arbitrary units) with solid, dash-dotted, and dashed lines, respectively. Right panel: temperature stratification as a function of geometric and optical depth of our hot penumbral and quiet surrounding model compared to the purely photospheric model-R of Fontenla et al. (2006).