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  Observing & photographing green flashes


To see green flashes a sea horizon is best but the view from a tall building or a hillside can suffice. Flashes are also visible from aircraft. A low horizon is needed because pure I-Mir and M-Mir flashes take place below the astronomical horizon. The apparent sea horizon dips lower by an amount depending on your height above sea level. Flashes made by wavy inversion layers do not need such low horizons.

Stand a few metres above sea level to see I-Mir flashes. M-Mir flashes require that you are above the inversion layer but the ideal height is a compromise because the higher you are above the layer, the shorter is any flash. In any event, inversion layers are often only a few feet above the surface.

Don't be deterred by thin haze. It will dim the sun, thick haze will hide the sun completely, but a good flash might still be visible.

Do not stare at the sun or look at it through any optical device - your eyesight could be permanently damaged. An I-Mir flash, the type most seen by eye rather than a camera, occurs just before the sun disappears altogether. Looking at the sun earlier will, as a minimum, bleach the red sensitive receptors of your retinas and impair your ability to see the flash faithfully. Don't take risks.

More images from Florian Schaaf's sunset sequence. Several frames contain flash fragments, the classical I-Mir flash occupies the second and third frames from the end and lasted 1-2s. The spiky horizon 'waves' are not real, they are part of the mirage and a sign that a flash might be visible. Images ©Florian Schaaf.