Synthetic transmission spectra of LTT 3780 c. Left panels: transmission spectra calculated without taking into account the opacity contribution of haze particles (soot). Top-left panel: variation of spectra with the strength of vertical mixing, corresponding to the cases in Fig. 11. Two middle panels: correspond to the two cases in Fig. 12. Bottom-left panel: transmission spectra of all 108 models in the two categories of strong (10⁶, 10⁸, or 10¹⁰ cm² s⁻¹) and weak (10⁴ cm² s⁻¹) vertical mixing. Right panels: same as left panels, but with opacity of haze particles taken into account.