Empirical TP profiles used as input for the spectral synthesis calculations. Black, red, blue, and green lines identify the models having a lower temperature, at the bottom of the atmosphere, close to 3500, 4000, 4750, and 5500 K, respectively. Solid lines are for profiles computed setting κ equal to 2.5, while dashed lines are for profiles computed setting κ equal to 3.1 The thick orange line shows the TP profile obtained for KELT-9b using PHOENIX.