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 – the cirlce around the anti solar point (shadow of your head) on which rainbows are seen. They can not be square or straight, because of the way rainbows are formed. Read about how a rainbow is formed to understand this better. Q. Can a rainbow be a complete circle? A. Yes. It is difficult to produce the conditions for this to occur. It isn’t really possible to have a complete circle fro
