Thursday, March 08, 2007
Reflected rainbows near Spitsbergen
On 22nd August 2006 between 20.35-20.50 hrs, while cruising on the Isfjord near Spitsbergen, Nicola Boll watched these wonderful reflected rainbows. The lower bow is an ordinary primary bow. Intersecting it and curving upwards above it is a 'reflection bow'. The bow is formed by sunlight reflected off the smooth waters of the fjord. The upward going reflected rays are, in effect, from a 'virtual sun' the same distance below the horizon as the real sun was above it. Since rainbows are always centred opposite the light source, the centre of the reflected bow is up in the sky and the bow correspondingly high. In the picture enhanced by unsharp masking a reflection bow is also visible curving upwards above and to the right of the secondary rainbow.