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Rayleigh scattering in Earth’s atmosphere makes the daytime sky appear blue.

The Claim

The sky is blue.

Verified by Lenz ·

The Short Version

The claim matches well-established scientific explanation and ordinary observation. Multiple authoritative sources explain that atmospheric Rayleigh scattering makes the daytime sky appear predominantly blue to human eyes. Technical nuances about violet light, perception, or “bluish white” descriptions do not change the practical truth of the statement.

Caveats

  • The claim describes the sky’s usual daytime appearance; it is not blue under all conditions, such as at sunset, sunrise, or heavy overcast.
  • A physically exact description can be more nuanced than everyday language, since scattered light is not a perfectly pure spectral blue.
  • Violet light is scattered even more than blue, but human vision and atmospheric absorption make the sky appear blue rather than violet.

The Receipts

  1. Why Is the Sky Blue?

    NOAA NESDIS

  2. Why is the sky blue?

    NASA Space Place

  3. Why Is the Sky Blue? Understanding Rayleigh Scattering

    Arizona State University (ASU Learning Sparks)

  4. Blue Sky and Rayleigh Scattering

    HyperPhysics (Georgia State University)

  5. Why is the sky blue?

    Royal Museums Greenwich

  6. Why is the sky blue?

    University of California, Riverside

  7. Why is the sky blue and the sunset red?

    Royal Meteorological Society

  8. Rayleigh scattering | Chemistry | Research Starters

    EBSCO Research Starters

  9. Why is the sky blue?

    Royal Meteorological Society

  10. Why is the Sky Blue?

    European Southern Observatory (ESO)

+ 3 more sources — see the full list on Lenz

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