Airglow events visible to the naked eye

During IR photographic airglow observations covering several years, three naked-eye events have been recorded. Two of these are moving, luminous acoustic gravity wave groups of some 10-15-km wavelength, which occur near high lunar tide in the atmosphere. The events appear quickly, endure 0.5-1 h, then fade. Visible photos of two events appear enhanced while little enhancement is present in the IR photos, although the structures are well correlated. If these events are due to OH, we suggest that some unrecognized mechanism, perhaps a gravity wave interaction, enhances the visible transitions of the OH over the IR transitions. If the events are due to an unrecognized continuum emitter, perhaps NO, its emission must occur at the same height as the OH. Spectra seem to be the only reasonable approach to solving this problem.