blue
Blue is a color, it is red, green and blue light of the three primary colors in which a dollar, in which the three primary colors in its shortest wavelength (about 470-440 nm). As the dust in the air on the sun's Rayleigh scattering, the sunny sky is blue. Due to the hydrogen-oxygen bond in the water molecule, the absorption of light of about 750 nm, a large amount of water is concentrated together in blue, and the deuterium-oxygen bond absorbs longer wavelengths (about 950 nm), so the heavy water is colorless of. The complementary color of blue is orange. ...