Why is red on the outside of a rainbow and blue inside?
A. The colours are caused by the different wavelengths (same as saying colours) of light having different indexes of refraction (see question above). The maximum angle away from the anti solar point which light from the sun is refracted by the raindrops is greater for red than blue. Thus red is on the outside and blue is on the inside of the rainbow. Q. What is the shape of a rainbow? A. Rainbows are an arc at a constant angle from the anti solar point (shadow of your head). For a primary bow this angle is 42 degrees, and for a secondary bow 51 degrees. So the shape is an arc along the circumference of a circle. Q. Why do rainbows always appear round? A. Rainbows always appear round because they are formed at a constant angle around the anti solar point (the shadow of your head). The shape of something described by an arc a constant distance away from a point is a circle, which is called round. Q. Why are rainbows arcs or semi circles? A. Rainbows are usually only partial – part of – t
