Why does the sky appear blue during a clear day?
Answer and explanation
Correct answer: B. Rayleigh scattering of sunlight by atmospheric air molecules
- Step 1: Rayleigh scattering states scattered light intensity is inversely proportional to the fourth power of wavelength: I proportional to 1 / lambda^4. Step 2. Shorter blue wavelengths (approx 400-450 nm) are scattered much more strongly than longer red wavelengths (approx 700 nm). Answer: Rayleigh scattering of sunlight by atmospheric air molecules. Why not the others: Dispersion through water droplets produces rainbows; total internal reflection causes mirages; ozone absorbs UV radiation in stratosphere.
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