(Or baroclinicity.) The state of stratification in a fluid in which surfaces of constant pressure ( isobaric) intersect surfaces of constant density ( isosteric). The number, per unit area, of isobaric–isosteric solenoids intersecting a given surface is a measure of the baroclinity. If the surface is horizontal, this number is given by where α is the specific volume and the pressure. Barotropy is the state of zero baroclinity. See also barotropy.
In fluid dynamics, the baroclinity (sometimes called baroclinicity) is a measure of the stratification in a fluid. A baroclinic atmosphere is one for which the density depends on both the temperature and the pressure; contrast this with barotropic atmosphere, for which the density depends only on the pressure. In atmospheric terms, the barotropic zones of the Earth are generally found in the central lattitudes, or tropics, whereas the baroclinic areas are generally found in the mid-lattitude/polar regions.