Question

If the shape of the rainbow is circular, why are we unable to see the whole circle?

Answer 1

A rainbow is not actually shaped like a semicircle or an arc; that is simply the shape that we see. In fact, a rainbow is a circle, but we can’t see the full shape because the horizon cuts off the lower half. However, if you were flying high enough, without any disturbance, then you would be able to see a full rainbow.