Pressure temperature profiles of the four giant planets of the solar-system as derived from observations (dotted line, Lindal 1992) and from model D of Sect. 5.2 (plain lines). The thin lines are radiative regions whereas the thick lines are convective regions. For Uranus we plot two profiles: one with the measured value of the internal temperature T_int = 29.4 K (the hotter profile) and one with the 1-σ upper limit T_int = 35.5 K (the cooler profile). The fiducial model of Uranus have a deep radiative zone, it illustrates the difficulties of the method when a detached convective zone appears (here between 0.5 bar and 7 bar), since it is not taken into account by the analytical solution.