Synthetic observation of the KHI at 8.25 μm, with fixed observational angle β = 90° and α = 128° (cases E and G). Two different times are shown, left: t = 0.0084, right: t = 0.01 or 8.21 × 10⁴ and 9.78 × 10⁴ year, respectively). During this interval the development of small-scale perturbations in the nonlinear phase can be seen. A linear scale is used for the intensity of the images.