A rainbow is a phenomenon in which light rays get reflected, refracted and dispersed by the water droplets resulting in the spectrum of light. This phenomenon occurs immediately after rainfall due to a high humid atmosphere and in absence of air pollution.

A rainbow is the band of color that appears in the sky and can only be seen when the sun
shines through falling rain. This pattern of colors starts with red, orange, yellow, green, blue, indigo to violet.

A rainbow is formed when white light from the sun is entered into the water droplets and is refracted (bent), split into separate colors, and reflected back.

They are classified into two types of rainbow:

1. Primary Rainbow: A primary rainbow takes place in the atmosphere when light rays from the sun hit the water drops at a unique and certain angle. It is a phenomenon that is formed by processes that include: refraction of light, dispersion of light, internal reflection, and secondary
refraction.

2. Secondary Rainbow: A secondary rainbow formed by a secondary reflection of light within the raindrops. It is the only difference between a primary rainbow and a secondary rainbow. Therefore,
when we see the light reflected by the raindrops the spectrum of the light is
the exact opposite of that of a primary rainbow, which means the secondary
rainbow colors are like red on the inside and violet on the outside.

We see rainbows because of the geometry that is possessed by the raindrops. When the sun shines in the rain, incident rays of light from the sun enter the raindrops and are refracted inwards. They are reflected from the back of the raindrop and are refracted again when they exit the raindrop, returning to our eyes and letting to see this phenomenon.