Transmittance maps obtained with the simulation of the atmosphere of GJ 1214 b depicted in Fig. 8. The region shown between the inner white disc and the outer black dotted circle is an enlargement of the region delimited bywhite circles in Fig. 8. The white dotted circle corresponds to the effective radius: the radius of the opaque disc resulting in the same overall absorption as the simulation over a homogeneous stellar disc. The maps in the upperrow are obtained with Mie scattering turned off in order to show the effect of clouds. Clouds dominate near 0.95 μm, methane is the main gaseous absorber at 1.17 μm, and carbon dioxide at 4.30 μm.