As a scientist I guess I should stop and admire the beautiful natural world a bit more than I do. Too busy doing stuff most of the time, which is a poor excuse. Anyway, above is a picture of sunset over the river Seine in Paris. To the right you can see twin squarish towers, this is I think the Notre Dame cathedral.
The clouds are beautiful, wispy like cotton wool, and they are illuminated red by the setting sun. They are red because the sky is blue. All the photons in the picture came from the Sun but the predominantly blue ones from the sky were scattered (i.e., deflected) by the molecules in the Earth’s atmosphere into my phone camera. The predominantly red ones from the clouds came more directly from the Sun, many of the blue photons that arrived along the same path as these red photons were deflected up or down and so did reach my camera, leaving the red ones to dominate, colouring the clouds red.
Chance & Necessity 