The sky appears blue due to the scattering of sunlight by the molecules of gases (primarily nitrogen and oxygen) in the atmosphere. This phenomenon is called Rayleigh scattering. Sunlight is composed of different colors, each with a different wavelength. Rayleigh scattering is more effective for shorter wavelengths (like blue and violet) than for longer wavelengths (like red and orange). As sunlight passes through the atmosphere, the blue light is scattered in all directions much more than the other colors. Some of this scattered blue light reaches our eyes, making the sky appear blue. While 'Dispersion' typically refers to the separation of light into its spectrum (like in a prism), sunlight is composed of a spectrum of wavelengths. The scattering process acts differently on these wavelengths. Thus, the phenomenon involves the scattering of the dispersed (spectral) components of sunlight. 'Scattering' is the primary cause, and Option D includes it.
The sky is blue in colour due to:
Asked in APPSC Draughtman 2008 · Topic: Optics (Prisms and Dispersion)
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