Spectra for planets around the Sun (top panel), AD Leo (middle panel), and T3100, a model M dwarf with no chromosphere (bottom panel), all at a spectral resolution of λ/Δλ∼50. The black curve is a spectrum for a planet with 0 Sorg flux. The red and blue lines show model spectra for planets with 1 and 30 times the modern Sorg fluxes. The purple lines show spectra for planets with 30 times the modern day flux of CH3SH and 0.65 times the modern day flux of CH4. The cyan lines show spectra with 2 times the modern day flux of CH4 and 0 Sorg flux. The green lines show spectra with 1000 times the modern day flux of H2S and 0 Sorg flux. The goldenrod, orange, and brown dashed lines represent the Planck function for an object at 278 K (the surface temperature), 276 or 273 K (the highest “color temperature” for the “1 modern Sorg flux” spectrum), and 180 K (the stratospheric temperature).