  The turbulent Rayleigh--Taylor system in a rotating reference frame is
investigated by direct numerical simulations within the Oberbeck-Boussinesq
approximation. On the basis of theoretical arguments, supported by our
simulations, we show that the Rossby number decreases in time, and therefore
the Coriolis force becomes more important as the system evolves and produces
many effects on Rayleigh--Taylor turbulence. We find that rotation reduces the
intensity of turbulent velocity fluctuations and therefore the growth rate of
the temperature mixing layer. Moreover, in presence of rotation the conversion
of potential energy into turbulent kinetic energy is found to be less effective
and the efficiency of the heat transfer is reduced. Finally, during the
evolution of the mixing layer we observe the development of a
cyclone-anticyclone asymmetry.
