The blue colour of the sky and the reddening of the Sun at sunrise and sunset are caused due to the phenomenon of :
dispersion of light.
reflection and refraction of light.
aberration of light.
scattering of light.
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Answer is Right!
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UPSC CISF-AC-EXE – 2022
When sunlight enters the Earth’s atmosphere, it interacts with the gas molecules (mainly Nitrogen and Oxygen) and tiny particles present. This interaction causes the light to be scattered in various directions. This process is called scattering.
Rayleigh scattering explains why the sky is blue. It states that the intensity of scattered light is inversely proportional to the fourth power of the wavelength. Shorter wavelengths, like blue and violet light, are scattered much more effectively than longer wavelengths, like red and orange light. When we look at the sky during the day, we see the scattered blue light from all directions.
At sunrise and sunset, the sunlight travels a much longer path through the atmosphere to reach our eyes. During this long journey, most of the shorter wavelength blue and green light is scattered away by the atmospheric particles. The longer wavelength light, such as red and orange, which is scattered less, is left to reach our eyes, making the Sun and the sky around it appear reddish or orange.
– This interaction involves scattering of light.
– Shorter wavelengths (blue) are scattered more effectively than longer wavelengths (red) by atmospheric gases (Rayleigh scattering).
– The path length of sunlight through the atmosphere affects which colours are predominantly seen.