The atoms of nitrogen and oxygen in the atmosphere separate the sun’s white light into its many colors and scatter them throughout the atmosphere. The wavelength of the blue light scatters better than the rest, predominating over other colors in the light spectrum. This makes the sky appear blue to us on a clear day.
The scientific name for this phenomenon is ‘Tyndall Effect’, more commonly known as ‘Rayleigh Scattering’. This phenomenon describes the way in which light physically scatters, when it passes through particles in the earths atmosphere that are 1/10th in diameter of the color of light. The light spectrum ranges in wavelength from red to violet and since the wavelength of the blue light passes through the particles with greater ease than the wavelengths of other colors of light, the sky appears blue to the naked eye.
The human eye has three types of light receptors, known as cones, located in the retina. The cones are either considered to be red or blue or green, based upon their strong response to light at these wavelengths. As light stimulates these receptors, our vision translates the signals into the colors we see. The skylight stimulates the red and green cones almost equally, while stimulating the blue cones more strongly, resulting in the blue colour of the sky.