Class 10 Physics simulations · The Human Eye and the Colourful World

Scattering of light: blue sky, red sunset

Sunlight is scattered by the air. Change the height of the Sun and the size of the particles in the air.

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What to notice

Air molecules scatter blue light far more than red, so the sky is blue. At sunrise and sunset light crosses much more air, so mostly red reaches us.

Key relation

Scattering by very small particles ∝ 1/λ⁴ (blue scattered most)

Try this

Lower the Sun to 5°. Then make the particles large (cloud droplets): why do clouds look white?

What you can change

• Height of the Sun above horizon: 2 to 90 °
• Particles in the air: choose Air molecules (very small), Fine dust / smoke, Water droplets (large)

More in The Human Eye and the Colourful World

• Defects of vision and their correction
• Dispersion through a prism
• Total internal reflection

See all Class 10 Physics simulations or every Physica simulation.