The numerical strategies, formulation and parameterizations utilized in fashions of the circulation of the environment and ocean might be described intimately. Extensively used numerical strategies would be the focus however we may also assessment rising ideas and new strategies. The numerics underlying a hierarchy of fashions might be mentioned, starting from easy GFD fashions to the high-end GCMs. Within the context of ocean GCMs, we are going to describe parameterization of geostrophic eddies, mixing and the floor and backside boundary layers. Within the environment, we are going to assessment parameterizations of convection and huge scale condensation, the planetary boundary layer and radiative switch.