# Barotrope

In Mechanical of the fluids, a fluid barotrope , is that whose lines of equal Pression are parallel with those of equal Densité ( isopycne ). This qualifier is used in several fields of which the Météorologie, the physical Océanographie and the Astrophysique to describe gases or liquids of which propriétées do not vary with the thickness.

## Consequences

In an ideal fluid barotrope, the variation of the pressure is done only with the variation of the density: $\, P = P \left(\ rho\right) \ propto P \left(T\right)$. This wants to say:
• that the Température (T) is everywhere equal to a pressure level (P)

• that a flow with a given pressure level does not change the temperature on this level. It is thus strongly constrained
• that a disturbance barotrope is a disturbance in flow coming from the horizontal shearing of the basic flow, and not of the conversion of the potential energy into kinetic energy

The image of right-hand side shows the vertical stratification of the density and the pressure. Notice that one gave a slope to these lines. If one made a cut according to the horizontal one, one would see that the pressure changes when one goes from has to B, in the same way that the density. It is what one observes in a chart on constant level, like a chart of surface of the weather systems, when it is seen that the Isobare S are parallel to the Isotherme S.