Abstract
An extension to the Gossard-Munk impedance relation, valid for large-amplitude, dissipative disturbances, is outlined. This new relation yields information on the dissipative properties of a convergence line if the associated wind and pressure perturbations as well as the propagation speed of the line are known. When applied to the gust fronts of squall lines and tradewind showers, it is found that the fractional dissipation rate increases with the non-dimensional amplitude of the disturbance.
