Top: spectral energy distributions (SEDs) of the red giant models with and without chromosphere. The blue line shows the average SED of the model without chromosphere computed using an ensemble of 20 model snapshots obtained at different instants in time. The red line shows the SED of the model with chromosphere computed using the single snapshot shown in Fig. 1. Bottom: relative difference between the flux of the models with and without chromosphere. The vertical scale is different in the wavelength region <270 nm.