Rainbows again

This blog is still loving the proliferation of rainbow posters in support of NHS staff. It's not been raining recently, fortunately, so we haven't had a lot of rainbows to look at. As I remember, for a normal rainbow, red is at the top and following the mnemonic Richard Of York Gave Battle In Vain, the colours go down to violet at the bottom, as shown in the poster above. That's unless there is a double rainbow, when the colours in the upper bow are reversed, or indeed when there is a supernumerary rainbow when you get pastel colours like pinks. https://en.wikipedia.org/wiki/Rainbow#Supernumerary_rainbows and http://wigtonphysics.blogspot.com/2009/11/wigton-church-stained-glass.html I hadn't realised that these latter gave the first proof of the wave nature of light, being an interference pattern not a refraction effect. So not all rainbows need to follow the traditional order! Perhaps this might excuse the old stained glass in Wigton church http://wigtonphysics.blogspot.com/2009/11/wigton-church-stained-glass.html