Atmospheric physics explains why the sky appears blue

The blue color of the sky is a result of sunlight interacting with the Earth's atmosphere through a process known as Rayleigh scattering. While sunlight appears white, it is actually composed of various colors, including red, orange, yellow, green, blue, and violet, each corresponding to different wavelengths.

As sunlight enters the atmosphere, it collides with gas molecules such as nitrogen and oxygen. Shorter wavelengths, specifically blue and violet light, are scattered more strongly in many directions compared to longer wavelengths like red and orange. This widespread scattering of blue light allows observers on the ground to see the blue color across the sky.

Although violet light has an even shorter wavelength and is scattered more intensely, the sky appears blue rather than violet because the Sun emits less violet light and the human eye is more sensitive to blue light.