Barotropic fluid

Water, which varies only a few percent with temperature and salinity, may be approximated as barotropic.

In astrophysics, barotropic fluids are important in the study of stellar interiors or of the interstellar medium.

One common class of barotropic model used in astrophysics is a polytropic fluid.

Hence, the motions of a rotating barotropic air mass is strongly constrained.

A fluid which is not barotropic is baroclinic, i. e., pressure is not the only factor to determine density.