At https://spaceweather.com (January 29th 2020) we have dunes in the sky, a form of aurora rippling through the northern skies. A paper published in the AGU Advances (January 28th 2020) describes the physics behind it. Dune shaped aurorae form in a narrow altitude range, 80 to 120km above the surface of the Earth. They have a pure monochromatic wavelength. They are also a mesopheric bore – resembling an atmospheric gravity wave that springs up from the surface below and becomes caught up in a thermal waveguide 100km high. When solar wind particles rain down they illuminate its rippling structure …
… monitoring dunes may reveal previously unknown waves and waveguides at the boundary between earth and space.