|Mock-Mirage Green Flashes, Finland imaged at Jakobstad Feb 17, 2009 by Jonas Förste.
©Jonas Förste, shown with permission.
There are several types of green flash but the ones most seen or photographed are (1) the classical 'Jules Verne' flash very close to the horizon as the last sliver of sun disappears and (2) ones like these, mock-mirage flashes on the top of the sun's still visible disk. Mock-mirage flashes are less conspicuous and more photographed than seen. Both are produced by mirages made in turn as the setting sun's light is abnormally refracted by passing through strong temperature gradients (therefore differences in optical refractive index) in the atmosphere. Mock mirage flashes are seen when you are above a temperature inversion layer,