I've done some reading through the literature on the dynamical cores of weather models. It isn't really true that vorticity is modeled as an additional set of

I've done some reading through the literature on the dynamical cores of weather models. It isn't really true that vorticity is modeled as an additional set of dimensions. Vorticity and divergence are an alternative description of the fluid velocity. They are the curl and div of the fluid velocity, respectively. Just as the fluid velocity may be discretized in 3 spatial and one time dimension, the fluid's vorticity and divergence may be discretized in three spatial and one time dimension.