Introduction
Mainly, refraction and dispersion of sunlight by water droplets or rain in the air form an arch of colors visible in the sky referred to as the Rainbow. The Rainbow consists of seven colors: green, yellow, red, orange, blue, violet and indigo. Debatably, in today’s society, rainbows are seen as a symbol of good luck, opposition, holiness, or even creation, but these mythical symbols differ from one community to another. However, rainbows are formed as a meteorological occurrence instigated by reflection, refraction, and dispersion of light in H2O droplets after a continuum of light in the sky. Therefore, in this regard, this paper seeks to explain how these beautiful formations come to be through physics.
Background
The Greek philosopher Aristotle made the first attempt to explain the Rainbow in around 300 BC. His fundamental idea was when the sunlight hits the raincloud, they all bounce back at a fixed angle. As sun rays are parallel, they will deflect at the same angle at all cloud points, forming a splash of different colors (Andreou, 2018). Aristotle further explained that if it were not for the appearance of the ground, we would see a full rainbow circle. Nevertheless, with shadows on their way, we can only see the arch shape. The Rainbow’s position is always dependent on the locus of the observer; thus, when we move, the angle of the Rainbow mythically moves with us; hence there is the myth, “pot of gold at the other side of the rainbow.”
In 1304 the German monk Theodoric opposed Aristotle’s hypothesis of the Rainbow coming from collective refraction and argued that each raindrop resulted in its Rainbow. Dominican Theodoric experimented with his hypothesis with a magnified drop, filled a spherical flask with water, and was able to trace the routes followed by the light rays that ended up forming the Rainbow, thus concluding that each raindrop in the cloud makes its Rainbow. Years later, philosopher Descartes employed and seconded monk Theodoric’s hypothesis.
Body
Legends and Symbolism of Rainbows Throughout History
Mainly, the Rainbow is seen as a symbol of hope in that it appears after rainfall and thunderstorms when everything seems to be at its darkest, then it forms and spreads light, thus hope. It also signifies new beginnings, and flashing back to the story of Noah in the Bible, the Rainbow appeared after massive destruction and was assigned a fresh start, thus relating to some societies to date. (Bolin, 2021) Typically this refers also to the Rainbow being a sign of promise and good luck. The unification of colors shows equality. In the pre-Islamic religion of the Arabians, the Sumerian god Ninurta defended Sumer with an arrow and bow and wore a crown referred to as the Rainbow (Cosgriff, 2019). Even though these symbolic representations differ from one society to another, most of these myths are strongly opinionated even to date. There is also a sequence of rainbow deities.
Notably, Amitolane is a rainbow spirit from the mythology of the Zuni located in Pueblo in South West US. It is a recognized Native American tribe. The Zuni residents refer to the Rainbow as Amitolane, representing a spirit. Characteristically, Kahukura or Uenuku is the God of rainbows in Maori mythology. The Maori believe that Kahukura fell in love with a mist maiden who later left him, and after a tiring search for a lost lover, he did not find her, so God turned him into a rainbow. Iris was the incarnation of a divine messenger and a rainbow for the ancient Greeks. They also believed that Iris was the dress of the goddess.
Norse religion was one of the traditional societies that believed in rainbow bridges. In North Europe, Scandinavia, this was a religion where the Vikings originated. Norse religion thought the Rainbow to be a road that connected the realm of the gods and the living realm. The appearance of the Rainbow in Scandinavia after the formation of Thor, God of thunder, signified eternity and a new beginning for the living dead. Classically, in Japanese mythology, the Rainbow was viewed as an inspiration for a floating bridge to heaven. Deities Izanagi and Izanami stood on this bridge as they brought the Japanese archipelago to existence. In Japanese mythology, the Rainbow was imaged as the path of a spirit and was depicted as sacred.
How Rainbows are Formed
Typically, despite many historical explanations behind the formation of the Rainbow and its imagery, there is a proven physics behind its formation as well. A rainbow’s primary formation results after a wave of light pass through a water droplet that eventually reflects a specific color. Each water droplet represents a tiny prism that forms a dispersion of pigments according to their wavelengths. Notably, red appears on the outer perimeter since it refracted at a steeper angle, and violet is at the bottom since it has the slightest steep angle of refraction. When viewed from the ground, these dispersed light rays form an arch since it blocks the other half. (Shaw, 2020)However, the Rainbow appears as a complete circle from an airplane view. The refraction, dispersion, and reflection portents transpire across the skyline, thus the formation of the Rainbow.
Types of Rainbows
Characteristically, there are four known types of rainbows; Primary rainbow forms between 40 and 42 degrees from the antisolar point. It involves one reflection inside the water droplet, and if the drop is 1mm and above, green, red, and violet are more bright with less blue, but if the droplet is smaller, red weakens, subsequently causing all colors to disappear in a fine mist. (Dang, 2020) Consequently, the secondary Rainbow involves two reflections inside the water droplet, which is around 10 degrees further than the primary Rainbow, with the one-tenth intensity of the primary Rainbow.
A supernumerary bow is a sequence of dimly colored bubbles mainly inside the primary Rainbow, thus making it dimmer and dimmer. Technically the bow gets weaker on each repeat, making it hard to notice. Finally, there is the lunar type of Rainbow, which, as the name states, is formed as light is diverted through water particles in the air. Notably, the lunar rainbows are much paler than their daytime forms, which is acquainted (Richardson, 2020). The size of a lunar rainbow depends on the moon’s height in the sky, and for it to be clear enough, the moon must be in its brightest phase. The full moon and water droplets should be on the opposite side of the moon. Thus this leads to forming of a transparent lunar rainbow or a moonbow.
Conclusion
This beautiful phenomenon of the refraction of light that passes through a water droplet can be clearly explained historically or rather through physics. Either way, there is the promotion of cultures and beliefs and, at the same time, the growth of scientific research. Therefore, from different researchers’ evidence and experiments, we can agree that the Rainbow is formed from the refraction and diversion of sunrays after they hit a water droplet.
References
Andreou, C. (2018). Reflection and the Aristotelian theory of Vision. In Proceedings of the XXIII World Congress of Philosophy.
Bolin, I. (2021). 12 Metaphors or Reality-Visions from the Past. Rituals of Respect. University of Texas Press.
Cosgriff, T. (2019). Raphael’s Rainbow and the Vision of Saint Catherine. Renaissance Quarterly, 72(1), 97-147.
Dang, N. L., Matlock, M. K., Hughes, T. B., & Swamidass, S. J. (2020). The metabolic Rainbow: Deep learning phase I metabolism in five colors. Journal of Chemical Information and Modeling, 60(3), 1146-1164.
Richardson, J. E., & Abramov, O. (2020). Modeling the formation of the lunar upper megaregolith layer. The Planetary Science Journal, 1(1), 2.
Shaw, J. A. (2020). Observing glories and cloud bows from an airplane. In Light in Nature VII