A green flash at sunset over Tràigh Thorastain, Coll. Here, the sun is setting across the Sea of the Hebrides just south of Berneray (Barra Head). A green flash lasts only a couple of seconds just as the sun sets; it is a result of refraction of the sun's rays by the atmosphere. It is an optical phenomenon caused by higher frequency light (green and blue) refracting (curving) more than red light, so remaining visible after the red light from the sun has sunk below the horizon. It is a magnification of the thin green line around the setting sun, which is usually not visible to the naked eye. It is best seen in clear air over the sea with no cloud on the horizon. I have only observed a green flash twice in the 5 years I have been looking - the other occasion being at Barvas, Lewis in July 2010.
24 August 2014
Red deer in Strathdearn
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Monadhliath
Red deer (Cervus elaphus) by flashlight in Strathdearn. To avoid the dark shadow to the right of the deer, more than one flash would be needed.
