Baroclinity

Measure of misalignment between the gradients of pressure and density in a fluid Density lines and isobars cross vertically in a baroclinic fluid. Visualization of a (fictive) formation of isotherms (red-orange) and isobars (blue) in a baroclinic atmospheric layering. A rotating tank experiment modelling baroclinic eddies in the atmosphere In fluid dynamics, the baroclinity (often called baroclinicity) of a stratified fluid is a measure of how misaligned the gradient of pressure is from the gradient of density in a fluid. In meteorology, a baroclinic flow is one in which the density depends on both temperature and pressure (the fully general case). A simpler case, barotropic flow, allows for density dependence only on pressure, so that the curl of the pressure-gradient force vanishes. Baroclinity is proportional to: ∇ p × ∇ ρ {\displaystyle abla p\times abla ho } which is proportional to the sine of the angle between surfaces of constant pressure and surfaces of constant density. Thus, in a barotropic fluid (which is defined by zero baroclinity), these surfaces are parallel. In Earth's atmosphere, barotropic flow is a better approximation in the tropics, where density surface