Rainbow is one of the most spectacular light shows observed on earth. It is the chromatic dispersion of light. Rainbows are optical and meteorological phenomena.

A rainbow is an arch of light exhibiting the spectrum colors in their order. The rainbow is made up of all the colors of the visible spectrum namely:

• Red, Orange, Yellow, Green, Blue, Indigo, Violet

Each color is bent differently. Red is bent the least, violet is bent the most. The colors can be seen, however, only when the angle of reflection between the sun, the drop of water, and the observer’s line of vision is between 40° and 42°.

Two physical phenomena are occurring within a rainbow:

1. Refraction
2. Reflection

Refraction occurs when sunlight enters a raindrop, it is broken into different colors heading in slightly different directions and bending at different angles depending on the wavelength of light.

Reflection occurs when the light is reflected off the back of the raindrop and passes back into the air again, in the process is further refracted. This is the prism effect wherein “white” sunlight is broken into a spectrum of different colors from red to blue-violet.

Rainbows can be observed whenever:

1. There are water drops in the air and sunlight shining from behind a person at a low altitude or angle.
2. The rainbow effect is also commonly seen near waterfalls or fountains.
3. Rainbow fringes can be seen at the edges of backlit clouds.

In the primary rainbow, the colors are arranged with the red outside. Occasionally, a second, dimmer, and thicker secondary rainbow is seen outside the primary bow.

Secondary rainbows are caused by a double reflection of sunlight inside the raindrops. The colors of a secondary rainbow are inverted compared to the primary bow, with blue on the outside and red on the inside.