The stability of the oceanic mixed layer is influenced by surface buoyancy and momentum fluxes: processes that add heat or fresh (less dense) water to the surface, such as solar heating, oceanic rainfall (precipitation), tend to stabilize the mixed layer by increasing the density contrast (making surface water lighter than water below); processes that remove buoyancy from the surface or add mechanical energy, such as evaporation (which increases surface salinity and density) and wind-driven mixing or surface gravity waves, tend to destabilize (promote mixing within) the mixed layer.