 Lorentz line shape

A normalized collisional line model ${\kappa }_{\nu }=(S/\pi )\Delta /[(\nu -{\nu }_0{)}^2+{\Delta }^2]$, with integrated strength $S$ and half-width $\Delta$. The centre scales as $S/\Delta$ and far wings as $S\Delta /(\nu -{\nu }_0{)}^2$. In a dilute pressure-broadened gas $\Delta$ scales approximately with pressure.