I captured these two rainbows a few weeks ago from Victoria.
The secondary bow has a radius of 51º and lies some 9º outside the primary bow. It is broader, 1.8X the width of the primary, and its colours are reversed so that the reds of the two bows always face one another. The secondary has 43% of the total brightness of the primary but its surface brightness is lower than that because its light is spread over its greater angular extent. The primary and secondary are concentric, sharing the antisolar point for a center. [Source: www.atoptics.co.uk]
Date and Time: August 9, 2008 at 19:53
Location: Victoria, BC
Optics: Canon EF 17-40mm f/4L USM
Camera: Canon 20Da
Exposures: One single JPEG light frame of 1/125 sec, f/11, at ISO 400
Process: Colour balance in Canon DDP.