Why is it darker outside a rainbow than inside?
A. The angle of the primary rainbow is determined by the maximum angle light which has passed through raindrops can be scattered away from the anti solar point. For the primary rainbow light is scattered at all angles closer to the anti solar, which means inside the rainbow. Thus the brighter area is light scattered by raindrops in which the light has reflected once inside the raindrop. The secondary rainbow is caused by light which has reflected twice inside raindrops and is the minimum angle towards the anti solar point which this light can be scattered. Thus the light area outside the secondary rainbow is light scattered after reflecting twice inside raindrops. Light which has passed through raindrops will not be scattered into the area between the primary and seconded rainbows, and this darker region is known as Alexanders Dark Band. In this region the light is either background light or light which has reflected off the surface of raindrops. Q. How do a rainbow get it’s colours? A
