  We study, via hydrodynamic equations, the granular temperature profile of a
granular fluid under gravity and subjected to energy injection from a base.
  It is found that there exists a turn-up in the granular temperature and that,
far from the base, it increases linearly with height. We show that this
phenomenon, observed previously in experiments and computer simulations, is a
direct consequence of the heat flux law, different form Fourier's, in granular
fluids. The positive granular temperature gradient is proportional to gravity
and a transport coefficient $\mu_0$, relating the heat flux to the density
gradients, that is characteristic of granular systems. Our results provide a
method to compute the value $\mu_0$ for different restitution coefficients. The
theoretical predictions are verified by means of molecular dynamics
simulations, and the value of $\mu_0$ is computed for the two dimensional
inelastic hard sphere model. We provide, also, a boundary condition for the
temperature field that is consistent with the modified Fourier's law.
