Adiabat

An adiabat is a curve representing a quasistatic adiabatic change. In a reversible description it is also a curve of constant entropy. For an ideal gas with constant heat-capacity ratio $\gamma$, it obeys $p{V}^{\gamma }=\mathrm{constant}$. A general irreversible adiabatic process need not follow this equilibrium-state curve and can produce entropy.