Mushroom sunset La Coruna, Spanish Atlantic
Imaged by Oscar Blanco 25th October '05. Image
As the upper sun descends a second sun climbs from
the ocean. The lower sun fragment is a rising inverted image
of the lower limb.
This remarkable mock-mirage sunset was
made by a strong temperature
produced by warm air from onshore overlaying cooler maritime air. The cooler
air below the inversion is visible a a darker band (greater optical extinction)
above the horizon. Its upper edge is is lit by the 'tin-hat' effect characteristic
of strong inversions.
The inversion here is so strong that 'ducting' is
taking place. Rays are trapped within the inversion layer and travel considerable
distances before escaping. Oscar estimates that he was no more than 30m
above the ocean surface and Andrew
Young estimates that the top of the
inversion layer was ~5m below.