Spatially integrated spectra of the relative transit depth (in ppm) expected for GJ 1214 b (left panel) and HD 209458 b (right panel) as a function of the day–night transition angle (β). The colour goes from red to green when β goes from 0 to 50° every 15°. The blue curve is the reference uniform case. Spectra with larger β are undistinguishable from the uniform case. The different labelled groups of curves are for our various sets of day–night temperatures. For each (T_day − T_night) group, the temperature at the terminator of all the models – including the uniform one – is (T_day + T_night)/2. Transit depth can be seen to increase monotonically when β decreases.