Rayleigh scattering
Rayleigh scattering explains why the sky is blue.
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It causes the blue color of the daytime sky because shorter wavelengths scatter more strongly than longer ones.[1][2] The phenomenon is named after the 19th-century British physicist Lord Rayleigh.[1] When light or other electromagnetic radiation encounters particles whose size is significantly smaller than the radiation's wavelength, the light is deflected or scattered; this process is known as Rayleigh scattering.[1]
Quick Facts
- Field
- Physics
- Nationality
- British
- Known for
- Rayleigh scattering, explaining the color of the sky
Facts from the source article.
Key facts and history
Around 1506–1510, Leonardo da Vinci conjectured that sunlight scattering off small particles gave the sky its blue hue.[3] Tyndall proposed this explained the sky's blueness but could not account for the preference for blue light.[4] By 1881, Rayleigh showed his equations followed from electromagnetism, using Maxwell's proof of light's electromagnetic nature.[5] Rayleigh scattering applies when the particle size parameter x is much less than 1.[6]
The scattering intensity for a single particle is proportional to the inverse fourth power of the wavelength.[1][6] Rayleigh scattering is also an important mechanism of wave scattering in amorphous solids like glass.[7] John Tyndall observed in 1869 that light scattering off extremely small particles produced a faint blue tint, a discovery made while he was checking for contaminants in purified air used in infrared experiments.[4] Lord Rayleigh published papers in 1871 that provided a quantitative description of Tyndall's effect, relating the scattering to the volumes and refractive indices of the tiny particles.[5]
By 1899, Rayleigh had extended his scattering model to apply to individual molecules, substituting terms for molecular polarizability in place of the earlier particulate volume and refractive index terms.[5]
What the research sources say
The Hyperphysics account states that Rayleigh scattering off air molecules gives the blue sky, and it is more effective at short wavelengths.[2] Hyperphysics describes Rayleigh scattering as elastic scattering where the photon energy is not changed.[2] The account explains that the almost white glare around the sun is due to Mie scattering, which is not strongly wavelength dependent.[2] The same source notes that water droplets in clouds, being much larger than air molecules, produce scattering that is nearly independent of wavelength across the visible spectrum.[2]
References
- Wikipedia, "Rayleigh scattering" (CC BY-SA 4.0), which cites: Lord Rayleigh (John Strutt) refined his theory of scattering in a series of papers; see Works. (original not read by us) en.wikipedia.org
- Rayleigh scattering. Hyperphysics.phy-astr.gsu.edu. Retrieved on 2018-08-06.. facts only, no text reused. hyperphysics.phy-astr.gsu.edu
- Wikipedia, "Rayleigh scattering" (CC BY-SA 4.0), which cites: Gonzalez, "Microchemical analysis of Leonardo da Vinci's lead white paints reveals knowledge and control over pigment scattering properties", Scientific Reports, 2020-12-10, p. 21715 (original not read by us) en.wikipedia.org
- Wikipedia, "Rayleigh scattering" (CC BY-SA 4.0), which cites: Tyndall, "On the blue colour of the sky, the polarization of skylight, and on the polarization of light by cloudy matter generally", Proceedings of the Royal Society of London, 1869, p. 223–233; Bohren, "The Optics Encyclopedia", Wiley, September 15, 2007 (we also read that source) en.wikipedia.org
- Wikipedia, "Rayleigh scattering" (CC BY-SA 4.0), which cites: Strutt, "On the light from the sky, its polarization and colour", The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 1871, p. 107–120; Strutt, "On the light from the sky, its polarization and colour", The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 1871, p. 274–279; Strutt, "On the scattering of light by small particles", The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, 1871, p. 447–454; Rayleigh, "On the electromagnetic theory of light", en.wikipedia.org
- Wikipedia, "Rayleigh scattering" (CC BY-SA 4.0), which cites: Seinfeld, John H. and Pandis, Spyros N. (2006) Atmospheric Chemistry and Physics, 2nd Edition, John Wiley and Sons, New Jersey, Chapter 15.1.1, (original not read by us) en.wikipedia.org
- Wikipedia, "Rayleigh scattering" (CC BY-SA 4.0), which cites: Mahajan, "Quasi-localized vibrational modes, boson peak and sound attenuation in model mass-spring networks", SciPost Physics, 2023, p. 069 (original not read by us) en.wikipedia.org
Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Rayleigh scattering (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Rayleigh scattering (CC BY-SA 4.0).
- Word definitions: the , each quoted from its Wikipedia article.
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