Example DIRTY model output spectra showing the variations in each dimension of the parameter grid. In each plot, we vary one parameter and fix all the others. The fixed parameter values are 10 Myr old stellar age, 10¹⁰ solar masses, solar metallicity, instantaneous star formation, ﹩{\tau }_{V,\mathrm{ext}}=1﹩, Milky Way type dust, shell geometry, 10 kpc radius, and clumpy dust, except when shown in the legend of each plot.