The formation of the rainbow

The Formation of the Rainbow

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The Formation of the Rainbow

The creation of the rainbow takes a sequence of physical happenings; refraction, reflection, dispersion and internal reflection. This is made possible owing to the interaction of light with air and water and the in-between boundaries. Research has it that for one to be able to view the rainbow clearly, they must have their back facing the sun, and viewing at an angel of 40 degrees above the ground into the atmosphere, where there are floating droplets of water or mist (Prigarin, et al., 2013)

A compilation of water droplets floating in the atmosphere acts as a light refractor.  When the light waves cross from one medium to the other, they refract. When light enters into a water droplet, it reduces in speed and in so doing it bends the conduit of light into a normal line. But upon exiting the droplet it increases speed and exits from the normal line. There are many paths in which a ray of sunlight can pass through a droplet of water, and each path is differentiated by how it bends towards or away from the normal line.

When a light ray has refracted twice and reflected once it is isolated and bent downwards in the direction of a person looking at the earth’s surface. The rainbow is usually observed as a circular arc in the sky but when looking it from an airplane it can be a full circle. This arc is as a result of the droplets in the atmosphere absorbing the isolated light at angles of movement away from the original path of the sun. Each drop of water within the arc disperses and refracts the entire spectrum (ROYGBIV).

The red color is refracted at vertical angles towards the earth than the blue color. Therefore when someone sights the rainbow at a steeper angle from the ground, the droplets of water from that angle refract light to the person’s eye. The blue radiance passes through a less vertical angle and is projected above the observers’ eye. This explains why the red color is at the top or outer boundary of the rainbow, and the blue one is at the inner part of the rainbow.

Researchers have also discovered the existence of secondary rainbows. Secondary rainbows often occur as a result of double reflection of the sunlight inside the droplets of rain. The colors of the second rainbow appear faint and are inverted with the blue color being on the outside of the rainbow and the red color on the inside. This is as a result of more light escaping from the effect of two reflections as compared to the primary rainbow and because it is spread over a wide area of the sky (Brasch, 2010). There is also the existence of the twin rainbow that constitutes two separate and concentric arcs. This type of rainbow is very rare to occur.

Rainbows form an important part of human culture. In ancient mythology, rainbows have been used in arts and even one of the legendary occurrences of a rainbow. In the Biblical story of Noah the rainbow acts as a sign of a covenant not to destroy the earth with water again.

In conclusion, rainbows are not necessarily limited to the scattering of light by raindrops. There are a number of factors that can contribute to the formation of a rainbow. Splashing of water at a waterfall can cause a mist of water in the air that can result in the development of a rainbow. Sunlight, suspended water droplets, and a good sighting are the major constituents of viewing the rainbow.

References

Brasch, N. (2010). Tricks of sound and light. Mankato, Minn.: Smart Apple Media.

Prigarin, S. M., Bazarov, K. B., Kerscher, M., & Oppel, U. G. (2013). Numerical study of rainbows and glories in water-drop clouds.Russian Journal Of Numerical Analysis & Mathematical Modelling, 28(3), 245-266. doi:10.1515/rnam-2013-0015