Why rainbow has a bent sructure?

Question

Why rainbow has a bent sructure?

Answer 1

Sunlight (all colors) striking tiny water droplets in the air is refracted by the small spheres of water.

The angle of refraction depends upon the wavelength of the light, with red light deflecting the most, and violet light the least.  The light deflects in all directions, so you end up with concentric cones of light, each of a different color.

This is visible to us as concentric circles around the light source (usually the Sun).  However, the ground often gets in the way of the lower part of the circles, leading to the typical half-circle arch.

Answer 2

A perfect answer above.