That's a pretty sight and a real show stopper when seen. We've few here in L.A. because it does not rain that often. The one question I've asked many times and to many people about them, I've never gotten an answer about. Why is it that the shade of the sky above the rainbow appears darker than the shade of the sky below it? (In this case to the left of the rainbow the sky appears darker.) Does anyone know?
From Wikipedia: The sky inside a primary rainbow is brighter than the sky outside of the bow. This is because each raindrop is a sphere and it scatters light over an entire circular disc in the sky. The radius of the disc depends on the wavelength of light, with red light being scattered over a larger angle than blue light.
Thank you.
