The color of light from the sky is a result of Rayleigh scattering of sunlight, which results in a perceived blue color. On a sunny day, Rayleigh scattering gives the sky a blue gradient, darkest around the zenith and brightest near the horizon.

The daytime sky appears blue because air molecules scatter shorter wavelengths of sunlight more than longer ones (redder light).

The light travels in waves that are too small and fast for us to see. Colors like red, orange, and yellow travel in longer waves and have less energy. Colors like blue, indigo, and violet travel in shorter waves and have more energy. When light is moving through the atmosphere, some of the waves are scattered, which gives the sky its color.

In a RGB color space, hex #87cefa (also known as Light sky blue) is composed of 52.9% red, 80.8% green and 98% blue. Whereas in a CMYK color space, it is composed of 46% cyan, 17.6% magenta, 0% yellow and 2% black.