Why is the sky blue?

2000/02/16 Elhuyar Zientzia

• Fisika

The light coming from the Sun is composed of waves of different wavelengths, and each wavelength is colored. On the other hand, when light passes through the Earth's atmosphere, it collides with the gas molecules and particles in it. Consequently, waves that circulate directly to the ground spread in all directions.

This effect is called "Rayleigh diffusion." But not all waves or colors spread the same way. Short wavelength waves disperse more than others, so we see the blue sky, which is the blue with the shortest wavelength of the colors that make up the light.

Even in the cinema, if we look at where the projector is, we will see that the light that comes from there is blue. This is because dust particles in the air act the same way as the atmosphere.