Blue

:For other uses, see Blue (disambiguation)

Sky

A clear sky on a sunny day appears blue because of Rayleigh scattering of the light from the Sun. Large amounts of water appear blue because red light around 750 nm is absorbed as an overtone of the O-H stretching vibration. Interestingly, heavy water is colorless, because the absorption band (~950 nm) is outside the visible spectrum.

Related Topics:
Sky - Day - Rayleigh scattering - Sun - Water - Heavy water

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