absorption line from the chromosphere
Most of the absorption line comes from the photosphere in the region where the temperature is still dropping.  Nevertheless, you can also get an absorption line where the temperature is rising, due to scattering effects.  The Kirchoff-Bunsen law you describe is a simplified rule that assumes the lines form in thermal equilibrium with the local temperature, but sometimes scattering produces non-thermal-equilibrium ("non-LTE") effects.  With scattering, line photons that get absorbed get re-radiated right away without coupling to the local temperature, and their re-emission has a 50% chance of being radiated back downward, where they will be reabsorbed deeper in the atmosphere.  This contributes to absorption, especially near line center (and can cause a feature called "central reversal" there).  But it is true that you can also get emission lines from very strong chromospheres where the Kirchoff-type effect does occur, see the profiles from chromospherically active dwarf stars (called "dMe stars").