modèle de nuage

CONT: There are several serious difficulties in including clouds in models. First, cloud properties are largely subgrid-scale. Even the most regular layered cloud systems have wide variations on a 100-km scale, and boundary-layer cumulus clouds can be of a scale less than 1 km. ... Second, there is a wide variety of cloud types, each of whose radiative properties varies widely from cloud system to cloud system. ... The third, and perhaps most serious difficulty, is that processes of cloud formation and cloud radiative properties have not been satisfactorily related observationally to other meteorological processes. ... As a consequence of the limitations discussed above, the current approach of modellers is to make up some ""cloud model"" based on simple physical arguments, include this parameterization in a GCM simulation, and compare the resulting model cloud climatology with one or several observational climatologies.