One of the most important problem in turbulence is the prediction of large-scale structures of very high Reynolds'flows. The class of two dimensionnal and geostrophic flows is relevant for geophysical applications (ocean and atmosphere). We consider the two-dimensional Navier-Stokes equation with weak stochastic forcing and dissipation in the inertial limit. This is an example of dynamical system, where an out of equilibrium stationary state is reached, without detailed balance. The existence of an invariant measure has been mathematically proved recently, together with mixing and ergodic properties. This problem has however never been considered from a physical point of view. We thus address the following issues: when is the measure concentrated on an inertial equilibrium, how are the large scales selected by the forcing, what is the level of the fluctuations ? The most striking result is the existence of out of equilibrium phase transitions. One observes transitions from one type of flow (unidirectional) to an other one (dipole), at random time. This is similar to the classical two wheel potential with noise. By contrast, in our case, no such potential exists and the turbulent nature of the flow (infinite number of degrees of freedom) renders the phenomena richer. Analogies with the Earth magnetic field reversal, and with similar phenomena in experiment of two dimensionnal and geophysical flows will be discussed.