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On the scientific explanation of parhelia

Published online by Cambridge University Press:  01 August 2016

John B. Reade*
Affiliation:
Mathematics Department, The University of Manchester Ml3 9PL

Extract

The cover picture shows a 22° halo seen in Preston on Sunday 28 October 2001 at 10 am. In contrast with a rainbow, the red band is on the inside rather than the outside, the colour bands are much thinner, and the arc is centred round the sun instead of being opposite to the sun. Also, it is not raining. Haloes occur on still sunny days when there is plenty of cirrus cloud. It is possible to see a full circle depending on how high the sun is in the sky. This never happens with a rainbow except when seen from an aeroplane. Sometimes the colours are particularly vivid at the 3 o’clock and 9 o’clock points. These vivid areas are called parhelia or mock suns. Sometimes the parhelia are all that can be seen.

Type
Articles
Copyright
Copyright © The Mathematical Association 2003

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