Which physical process governs the whiteness of clouds when sunlight hits water droplets roughly the same size as or larger than the wavelength of visible light?

Answer

Mie scattering

Mie scattering is the key mechanism responsible for the whiteness of clouds, occurring when water droplets are large enough (similar size or larger than visible light wavelengths) to scatter all colors equally.

Which physical process governs the whiteness of clouds when sunlight hits water droplets roughly the same size as or larger than the wavelength of visible light?
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