Have you ever wondered why the sun seems to change color as it dips below the horizon? It's a captivating phenomenon that has intrigued humans. While many believe that the sun itself is altering its hue, the truth lies in the Earth's atmosphere. In this article, we'll delve into the science behind sunset's stunning color transformations!!
The Composition of Sunlight
Sunlight represents parts of the electromagnetic spectrum, like infrared, visible light, and ultraviolet light. When sunlight reaches Earth, it goes through the atmosphere. Sunlight is a mixture of all the colors of the rainbow. This phenomenon can be demonstrated through a simple experiment using a prism. When sunlight passes through a prism the different colors that make up the lights are bent (at slightly different angles). This causes the light to be separated into its component colors, creating a spectrum of colors similar to a rainbow.
You can watch the prism experiment with an explanation here!
The Earth's Atmosphere as a Filter (Scattering light)
Atmospheric particles play a role in scattering sunlight. These particles, which include dust and air molecules interact with the incoming light waves. When light goes through a prism it separates into different colors. (This is called dispersion). Different colors of light bend at different angles because they move at different speeds in the prism. Shorter colors (wavelengths) like blue and violet bend more than longer colors (wavelengths) like red. (It's why the sky is colorful at sunrise and sunset and is blue during the daytime.) The Earth's atmosphere acts like a big prism, bending the different colors of sunlight.
The Path Length of Sunlight and the changing color.
During the day, the sun is high in the sky (meaning its light has to travel through a thin layer of the atmosphere). However, as the sun begins to set, it descends lower in the sky. This means that its light must now travel a much thicker layer of the atmosphere. As the sun's light passes through this thicker layer, it interacts with more atmospheric particles. This increased interaction leads to more scattering of the shorter wavelengths of light, like blue and violet, as they pass through the atmosphere.
This scattering of shorter wavelengths leaves behind the longer wavelengths, like red and orange, which are less likely to be scattered. These longer wavelengths can reach our eyes, creating the typical orange or red hues seen during sunsets.
The captivating phenomenon of sunset\sunrise is a result of a complex interplay between sunlight, the Earth's atmosphere, and the principles of light scattering. As the sun descends below the horizon, its light must travel a thicker layer of atmosphere, leading to the scattering of shorter wavelengths and the dominance of longer, red and orange hues. So the sun doesn't change its color during these phenomena.
Works Cited
Energy Education. (2024). Sunlight, Sunlight. Available at: https://energyeducation.ca/encyclopedia/Sunlight (Accessed: 13 September 2024).
Met Office. Why is the Sunset Red? Available at: https://www.metoffice.gov.uk/weather/learn-about/weather/optical-effects/why-is-the-sunset-red (Accessed: 13 September 2024).
MITK12Videos (2013). Newton’s Prism Experiment. YouTube. Available at: https://www.youtube.com/watch?v=uucYGK_Ymp0 [Accessed 30 Sep. 2024].
TutorChase. How do different wavelengths affect light dispersion? Available at: https://www.tutorchase.com/answers/igcse/physics/how-do-different-wavelengths-affect-light-dispersion (Accessed: 13 September 2024).
UCSD. The light scattering phenomenon. Available at: https://caice.ucsd.edu/wp-content/uploads/2020/05/Light_Scattering.pdf (Accessed: 13 September 2024).
Wikipedia. (2024). Atmospheric refraction. Available at: https://en.wikipedia.org/wiki/Atmospheric_refraction (Accessed: 13 September 2024).
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