Introduction
When we look around, there are many questions one would want to ask. Although most of the answers are found through academic approaches, the truth is that the broadness of this discipline makes it challenging to exhaust every natural phenomenon. Among the many questions asked is the explanation for the color of the sky. Have you ever imagined why the sky is not another color but blue? Is it natural or there are contributing factors which make it blue?
Could it be as a result of our natural color blindness that makes us perceive it to be blue? Definitely the questions are countless. This research paper explores reasons, findings, theories and the truth, which surrounds the blue color of the sky and the occurrence of rainbows. In order to achieve this, the research mainly analyses findings, gathered from reputable sources, including but not limited to online articles and books.
Blue sky
When observed on a clear day, without clouds, mist or dust, the sky always appears blue. Although there are several theories, which explain this concept, it is believed that the blue color is as a result of atoms of oxygen and nitrogen found in the atmosphere (Jacobs 1).
Due to the presence of these particles, the white light from the sun is separated into several colors, which are then scattered all over in the atmosphere. Additionally, based on scattering properties of these colors, it has been found that blue light has a wavelength that scatters in the atmosphere better than any other color.
This means that blue light dominates the atmosphere, making the sky to appear blue when observed by the human eye (Rea 10). On the other hand, the sun appears orange and red during sunset because the blue light is usually scattered far away from the visible line. This scientific phenomenon that explains light scattering and the appearance of the sky is commonly referred to as the Tyndall effect or the Rayleigh scattering.
Tyndall effect
This theory was put forth by John Tyndall in 1859, explaining the color of the sky. According to his discovery, blue wavelength is shorter and gets scattered better than other wavelengths, when light is passed through a fluid with particles. From a real life perspective, this can be illustrated by shining white light through water that has soap or milk.
When observed from the side of the container holding the water, it is possible to observe the beam of white light by the blue light, which is scattered (Mara 23). However, the light that is observed at the end of such an experiment appears red after the beam has passed through the entire vessel of water.
A filter of polarized light can also be applied to investigate the scattering nature of light. This can be compared to the deep-blue appearance of the sky, when viewed through sun glasses. Although the concept is commonly known as the Tyndall effect, many physicists refer to it as the Rayleigh scattering, based on the studies that were done by Lord Rayleigh a few years after it was proposed by John Tyndall in 1859 (Rea 10).
In their explanations, Rayleigh and Tyndall argue that the blue color of the sky is attributed to the presence of water droplets in form of vapor and dust particles in the atmosphere. However, if this were true, color variation in the sky would be a common occurrence due to ever-changing humidity. Based on this argument, it was agreed that the presence of nitrogen and oxygen in the atmosphere is the most appropriate explanation for the blue color of the sky (Jacobs 1).
This was fully backed by Einstein in 1911 when he developed a formula applied in determination of scattering light in different molecules. The results were acceptable as they had experimental evidence. From this discovery, it was also observed that the scattering of light by molecules is made possible because light waves have an electromagnetic field, responsible for dipole moments in these molecules.
Even though the sky is blue, it is clear that clouds appear white in color when observed. This is based on the fact that they contain particles, which are believed to be greater than the wavelength of light (Mara 23). As a result, all wavelengths are scattered equally, a concept that is commonly known as the Mie scattering.
However, the possibility of smaller particles in the atmosphere cannot be ruled out. This explains why some regions are famously known because of their blue haze. It is believed that the interaction between terpenes and ozone leads to the formation of tiny molecules that are approximately 200nm in diameter (Jacobs 2). Importantly, these particles give an explanation for the blue color.
Nevertheless, an eruption or forest fire may emit particles into the atmosphere, which end up scattering the red light. In such cases, the results would depict the opposite of the Tyndall effect. Consequently, the moon may appear blue since red light is commonly scattered out. However, it is important to note that blue moon is a very rare phenomenon (Rea 10).
Rainbows
Besides observing a clear blue sky or clouds, human beings equally get fascinated by rainbows. How are rainbows formed? From Greek mythology, rainbows were believed to be the path for a messenger of gods known as Iris. On the other hand, Norse mythology proposed that a rainbow acted as a link between human beings and their gods (Lee and Fraser 33).
All these myths make the understanding of the rainbow quite fascinating to human beings. Are they natural in existence or they are formed? These questions have been answered by scientists who spent their time analyzing the scientific explanation for the existence of the rainbow.
A rainbow can be described as arc that appears in the sky with colored light. A fact to note is that rainbows have a relationship with water droplets and light. It is believed that this arc forms due to reflection and refraction of light, mainly from water droplets, arising from rain or mist in the atmosphere (Lee and Fraser 322).
In other words, rainbows occur when there is splitting of white light into different colors, caused by water. In this line of thought, it is important to underscore the fact that when light falls on a drop of water, it enters into the drop. This penetration allows refraction of various light colors, depending on their respective wavelengths (Dwyer 4). Additionally, this separation of refracted light is similar to the analogy of the glass prism effect.
Furthermore, the position of a rainbow is very important with regard to its relationship with the sun. Under whatever circumstances, a rainbow naturally occurs on the opposite direction of the sun as viewed by an observer (Dwyer 10).
This position is crucial in explaining why rainbows mostly appear in the afternoon, when the sun is slightly low in the sky. If this occurs in the afternoon, the arc usually appears to the east of the person observing it and to the west if it occurs in the morning. On the other hand, the shadow of the observer is always at the center of the arc, with the rainbow forming the upper segment of the circle.
Besides the position of the rainbow, it is worth noting that the angle of reflection of its light to the eye is 42o to the initial ray of light. Its bow-shape is believed to be a portion of the cone of light that is blocked by the horizon (Dwyer 10). Another important fact about rainbows is that no one can move ahead of it. If you tried to overtake the rainbow to be on the other side, it would appear moving, thus making it impossible to see the end of a rainbow.
Moreover, every person sees a different rainbow since the angle measured is based on the observer’s eye contact with the refracted light from the sun through a drop of water (Lee and Fraser 322). This therefore means that every rainbow observer is usually at the center of the cone formed by colored light. It is sometimes possible to observe a complete circle of the rainbow when flying or at the top of a mountain.
From the above analysis, it is clear that the blue sky and the rainbow are fascinating natural phenomena, whose existence has an array of scientific and traditional explanations. However, the two are closely linked to properties of light, with regard to the scattering effect. Nonetheless, contributions of John Tyndall, Lord Rayleigh and Einstein remain paramount in the understanding of this concept.
Works Cited
Dwyer, Jacqueline. Rainbows. New York: The Rosen Publishing Group, 2001. Print.
Jacobs, Marian. Why Is the Sky Blue? New York: The Rosen Publishing Group, 1999. Print.
Lee, Raymond, and Fraser Alistair. The rainbow bridge: rainbows in art, myth, and science. Pennsylvania: Penn State Press, 2001. Print.
Mara, Wil. Why Is the Sky Blue? Singapore: Marshall Cavendish, 2006. Print.
Rea, Thelma. I Wonder Why the Sky Is Blue. New York: Rosen Classroom, 2000. Print.