Rainbow Spokes  seen by Ern Mainka (photography site) in Australia 25th March '08. Image ©Ern Mainka, shown with permission.


Rainbows are actually disks of light brighter at their edges. The disks of each colour overlap but are of different sizes and hence we see their coloured edges - they are the bow.

The disks are centred on the antisolar point directly oppositie the sun and this is also where shadows converge by perspective.

The dark parts of the 'spokes' are where raindrops are shadowed by clouds and are therefore unable to glint light and contribute to the light of the disk. The spokes are related to - but not the same as - anticrepuscular rays