  From the point of view of tunneling, the physical meaning of the Davies
critical point of a second order phase transition in the black hole
thermodynamics is clarified. At the critical point, the nonthermal contribution
vanishes so that the black hole radiation is entirely thermal. It separates two
phases: one with radiation enhanced by the nonthermal contribution, the other
suppressed by the nonthermal contribution. We show this in both charged and
rotating black holes. The phase transition is also analyzed in the cases in
which emissions of charges and angular momenta are incorporated.
