Question

Why rainbow is curved if light always travels in a straight line?​

Answer 1

The rainbow is curved because of the required observation angle. Rainbows are always circular. ... Rainbows are formed by small water droplets (spherical in shape) in the air splitting the suns light into colors.

Answer 2

For a rainbow to be formed,light has to hit the water droplet at an angle. Rainbow is not a single strip of light,but a combination of a million droplets splitting light in all directions. Due to the effect of wind and the downward motion of the droplets,the rainbow appears to be curved.