When the sun set over Silloth, I realised I might have misunderstanding something for years. I know and teach that it is air molecules and fine dust in the atmosphere that scatter blue light. At sunset the light travels the maximum distance through air to reach us so all the blue light is scattered leaving the red end of the spectrum. I now realise that I thought the clouds were red because it was they that scattered the light. The clouds are red because they reflect the red light that is the result of the scattering. I think that the give away is that it is the bottom of the clouds that seem red.
