Sample Environmental Management Paper on Rainbow
Rainbow is regarded as one of the most magnificent aspects of nature. The occurrence of rainbow in various parts of the world is indeed countable. A rainbow is simply described as an arc of spectrum colors that appear opposite the position of the sun during a heavy downfall. It is one of nature’s most splendid masterpieces that provide a great demonstration of the dispersion of light. This is mainly because of the fact that a rainbow is only formed when there is sun or moonshine along with rainfall (Suzuki et al. 2). Rainbows can only be viewed whenever there is a heavy downpour and sunlight shining from behind a low altitude range (Lee et al. 19). The formation of the rainbow provides enough proof that visible light is composed of a spectrum of wavelengths that are displayed in form of different colors (Lynch et al. 53). The formation of a rainbow stems from the rain droplets which serve as reflectors. Thus, rain droplets serve as compulsory ingredients for the formation of a rainbow. A rainbow is also regarded as an optical phenomenon that consists of the primary rainbow and the secondary rainbow.
Formation of a Rainbow
A rainbow is an arc spectrum consisting of all the colors formed by the refraction and reflection of rays of light from rain drops appearing on the part of the hemisphere that is opposite the sun (Lynch et al. 1). Induced by interplay of light and droplets of rain, the formation of a rainbow commences when white light from the sun passes through spherical rain droplets that are suspended in the air. The ray refracts upon passing through the water droplets after which the light gets dispersed before undergoing an internal reflection. This is later followed by refraction of light which exits the water droplets in form of different colors. The resultant of refraction, internal reflection and refraction of light through the rain droplets is what culminates to a rainbow. Since the rainbow is always formed in the direction opposite that of the shining sun, an individual must be directly in front of the position of the sun in order to get a glimpse of the rainbow (Ho 2).
There are two major types of rainbows that may be formed. These are; the primary rainbow and the secondary rainbow. The primary rainbow is formed when one total internal reflection and two refractions occur from the suspended raindrops (Lee et al. 3). On the other hand, Suzuki et al. (3) noted that the secondary rainbow is usually formed as a result of two internal reflections and two refractions emanating from the water droplets that have been suspended in the air during a heavy rainfall.
The primary rainbow occurs as a result of a single internal reflection and two refractions of light from the sun through the suspended water droplets. The primary rainbow can be identified by a single bright arc that usually appears after a rain shower. The arc or bow that usually appear opposite the direction of the sun occur when the refracted rays deviate directly back towards the light emanating from the sun (Lee et al. 15). The primary rainbow is further characterized by an angular radius of approximately 42 degrees with a width of approximately 2 degrees (Dudeja 22). Additionally, the sky with the primary rainbow looks brighter as compared to the surrounding sky (Lee et al. 19). Thus, the primary rainbow is viewed as the brightest type of rainbow with a radius subtending an angle of 40 degrees at the observers’ eye which is commonly described as the anti-solar point (Suzuki et al. 2). Additionally, the inner edge of the primary rainbow is usually violet in color whereas the outer edge is characterized by a red color.
The secondary rainbow is considered to be less bright as compared to the primary rainbow. A secondary rainbow occurs just beneath or outside the primary rainbow. This form of rainbow occurs as a result of rays of sun light entering suspended drops of water through the process of two internal reflections and two refractions. The colors of the secondary rainbow are usually a reverse of the colors of the primary rainbow (Lynch et al. 53). The secondary arc is also described as being broader in comparison to the arc formed by the primary rainbow (Lynch et al. 53). The inner edge of the secondary rainbow is characterized by a red color whereas the outer edge of the rainbow is usually violet. The difference in color is described as being reversal from the primary rainbow. This is mainly due to an additional reflection that causes a 180-degree reverse of the primary rainbow color sequence (Suzuki et al. 5). The secondary rainbow has an angular radius of approximately 50 degrees, thus its position being outside of the primary arc (Ho 21). A secondary rainbow is blurry and rarely observed as a result of its weak and faintly colored rings. In general, a typical rainbow would consist of a primary rainbow, a secondary rainbow with an Alexander’s space in between the two rainbows.
Aside from the sun serving as the primary natural source of light for the rainbow formation, the moon may occasionally play the role of producing light that is necessary for the formation of a rainbow. The type of rainbow that is usually formed as a result of the production of light reflected off the surface of the moon is referred to as the lunar rainbow. Commonly referred to as moon-bow, lunar rainbow is formed in the same manner as the primary rainbow with the only difference being the different source of light (Lee et al. 96). The lunar rainbows are weaker and fainter in comparison to the solar rainbow. This is primarily because of the less amount of light being reflected from the moon as opposed to the unlimited amount of light that is usually reflected from the sun (Lee et al. 101). Therefore, the formation of lunar rainbow requires a full moon so as to produce and reflect sufficient light to the rain droplets.
Moonbows are rare as compared to both primary and secondary rainbows. Essentially, a lunar rainbow only occurs a few days prior to the full moon phase. It is however difficult for individuals to discern the different colors formed on the lunar rainbow. However, an individual can only be able to view the lunar rainbow in occasions where the moon is nearest to its brightest phase or is a full moon (Dudeja 6). Even though lunar rainbow rarely occurs around the world, there are a few specific places where people have actually got a glimpse of a lunar rainbow. Example of such places includes; Yosemite National Park and Cumberland Falls in the U.S, the Victoria Falls in Zambia and Cumberland Falls near Kentucky (Ho 44). As a result of the relative low amount of light reflected from the full moon, an observer may hardly identify the lunar rainbow which usually appears as plain white or grayish white in color.
The Colors of a Rainbow
A rainbow is essentially made up of seven colors namely; red, orange, yellow, green, blue, indigo and violet. Each of the seven rainbow colors has their own specific wavelength. Thus the different colors appear in a specific sequence as determined by the different wavelength. The rainbow colors are classified as visible light with a wavelength falling in between the Ultra Violet (UV) rays and Infrared rays (Suzuki et al. 3). Red color has the shortest wavelength whereas violet has the longest wavelength. Thus, the arrangement of the rainbow color appears from the color with the shortest wavelength progressing to colors with longer wavelengths.
Fundamentally, the colors of the rainbow are normally formed by refraction, internal reflection and second refraction of rays of light in individual droplets. Due to the large number of droplets, they would all reflect a single color to the eye of the observer. Consequently, there several types of rainbows, with the primary rainbow regarded as being more visible in comparison to both the secondary rainbow and lunar rainbow which appear faint or blurry for human observation. In addition, the color sequence of the primary rainbow that usually starts from violet to red is usually displayed in a reverse sequence by the secondary rainbow.
Below is a diagram showcasing the processes involved in the formation of a Rainbow.
Source: “Kamal Al-Din Al-Farisi’s explanation of the rainbow.” Humanity & Social Sciences Journal
A diagram showing the difference between the Primary Rainbow and Secondary Rainbow
Source: “Primary and Secondary Rainbows”. Hyperphysics.phy-astr.gsu.edu.
Dudeja, Ravi R. Crash Course in Aieee Physics 2009. Pearson, 2009.Internet resource.
Ho, Mae-Wan. Living Rainbow H2o. Hackensack, N.J: World Scientific, 2012. Internet resource.
Lee, Raymond L, and Alistair B. Fraser. The Rainbow Bridge: Rainbows in Art, Myth, and Science. University Park, Pa: Pennsylvania State Univ. Press, 2001. Print.
Lynch, David K, and William Livingston. Color and Light in Nature. Cambridge: Cambridge University Press, 2004. Print.
Suzuki, Masatsugu, and Itsuko S. Suzuki.”Physics of rainbow.” (2010).
Topdemir, Hüseyin Gazi. “Kamal Al-Din Al-Farisi’s explanation of the rainbow.” Humanity & Social Sciences Journal 2.1 (2007): 75-85. http://s3.amazonaws.com/academia.edu.documents/6221916/kamalrainbow.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1496780031&Signature=A5U9cW9pGhu2l3WKyliMqZkV8Ac%3D&response-content-disposition=inline%3B%20filename%3DKamal_Al-Din_Al-Farisis_Explanation_of_t.pdf
Nave, C. R. “Primary and Secondary Rainbows”. Hyperphysics.phy-astr.gsu.edu. N.p., 2017. Web. 6 June 2017. http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/rbowpri.htm