Supernumerary

A rather tiring day, not helped by a vaguely sore throat and tickly nose, which will hopefully come to nothing...

In the morning we went to visit Molly, who seemed a little more confused than on our last visit, possibly the result of an infection. We spent a lot of time trying to reassure her, but very little of what we said seemed to be retained. So difficult.

Then Pete and I drove to the community orchard at  Bourne Woods where I was presenting the prizes for a local photographic competition that I judged recently. Fortunately the heavy morning rain had  stopped, but it was very wet underfoot, and it was only when we'd arrived that I realised I'd forgotten to pack my walking boots - so I ended up with very soggy feet. 

I was going to blip a medlar, a rather unusual member of the Rose family that is only edible when it's nearly rotten or bletted (see extra) but just before dinner the sun came out briefly, producing a beautiful supernumerary rainbow over our house. 

Supernumerary bows occur when raindrops responsible for the main rainbow are more-or-less uniform in size. Slightly different ray paths through a raindrop yield slightly different path lengths and slightly larger exit angle. As a result, there is constructive and destructive interference of each color in the spectrum as a function of ray exit angle, and a set of bows become visible inside the primary rainbow. Usually, there is some variation in size of raindrops, and the supernumeraries are washed out altogether. There is almost always some washing out of colors, and the bows show much green and red in them, and not the other colors in the spectrum.