SEDs from the far-infrared to the radio, observed for each cloud. The fluxes observed at 160 μm, 870 μm and 1.2 mm are fitted with a single modified black body either with an emissivity index of 1 (dashed blue line) or 2 (plain red line) or with a free emissivity index (dotted green line). Radio fluxes (or upper limits) computed in the same regions are overplotted and the extrapolated free-free emission is displayed as a black line. This shows clearly that the sub-millimeter and millimeter emission is dominated by dust emission rather than free-free.