Does Antarctica really have the bluest sky in the world?

On holiday the sky may look a deeper shade of blue than even the clearest summer day at home. The blue of the sky is the product of Rayleigh scattering, which affects light more at the blue end of the spectrum. High humidity and dust, as well as smoke and pollutants, also scatter light, but over a wide range of wavelengths. At higher altitudes there is less atmosphere above to scatter light, so the sky is darker and the blue may appear more intense. Antarctica is the likely winner for deepest, most saturated blue sky, as it combines high altitude with extremely low humidity and pollution.