He had read about rainbows in a soppy picture book, but then he had started to see them in the streets in London after it rained, when the petrol from the cars stained the tarmac and the water fanned out in broken purple, blue, and yellow rings.
It´s not
exactly a rainbow, but we all have seen it on a rainy day on the road. The description
in the text is very good, rings are formed, not
archs, the complete circumference. This effect is produced because
petrol, like oil, is immiscible with water and stays upon a puddle on the road.
Then, a triple layer air-petrol-water appears, which produces a game of
refractions that separates the light into its colours
