Cloud Iridescence

I noticed the coloured clouds as Gus and I were going for our morning walk, they were high in the atmosphere and there were lower-level clouds scudding underneath them obscuring the sun.  Of course, I didn't have my camera.  A walk with Gus is now short in distance, but takes almost as long as the ascent of the Knott that we used to do every morning.  The advantage is that the walk is also later, or else I might never have seen these clouds with the sun lower in the sky.

Anyway, they were still showing when we got home, and there was time for a photograph while the sun was still behind our neighbour across the road's house.  It seemed fitting somehow that Kirstie and Rob, who live there, had the removals men in today, they are leaving Arnside for South Wales.  So I shall be able to send them this as a goodbye present.

According to the source of all knowledge, Wikipedia, iridescent cloud is caused by small water droplets or ice crystals individually scattering light.  Where the droplets or crystals are of similar size, their cumulative effect will be seen as rainbow colours.  The cloud apparently must be thin so that most rays encounter only a single droplet.  For this reason, the phenomenon is more likely to be seen at the edge of clouds, which is what I have seen previously.  Today was unusual for the extent of the effect in the sky.