Variation of the temperature with atmospheric height corresponding to various atmospheric models available in the literature. In particular, the E model of Avrett (1981), the models by Maltby et al. (1986) and Fontenla et al. (2009) that cover from the photosphere to the chromosphere, and the model of Collados et al. (1994; cool umbra and hot umbra) that only covers the photosphere. The optical depth scale has been calculated using the Maltby et al. (1986) atmospheric model.