Green Flash from Tenerife

December 23, 2004


Provided and copyright by: Tony Cook
Summary authors & editors: Tony Cook

The above photo showing the "green flash" was captured on October 24, 2004 from Palm Mar, on the island of Tenerife in the Canary Islands (Spain). This is an excellent example of a mock mirage/green flash, photographed as the Sun was setting behind the neighbouring island of Hierro.

Green flashes are created by variations in refraction near the horizon. The refractive layer causes sunlight to be weakly dispersed into the constituent colours of red, yellow, green, blue and violet. Violet and blue light are normally scattered in the Earth's atmosphere, with the result that the last portion of the dispersed light to be observed as the Sun sets is green.

Green flashes come in a variety of types, all related to the formation of mirages. Examples include the inferior-mirage flash and the mock-mirage flash. The mock mirage type is produced by a weak thermal inversion. The flash is the green rim of the dispersed solar image, magnified at the thermal inversion boundary. When the green rim reaches the magnifying zone, the keen eyed observer may see a flash of emerald coloured light.

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