When white light falls on a surface that separates two media, a range of colors appears. This phenomenon is called light scattering and occurs due to the difference in incidence of refraction, as well as the difference in speed of propagation of the light beam. When light is traveling in air and hits a glass prism, for example, its speed changes to another value, which is lower than when it was traveling in air.
This phenomenon is also responsible for the formation of the rainbow . After the rain, tiny droplets of water are suspended in the air. When falling on these droplets, white light, coming from the Sun, undergoes the phenomena of refraction and dispersion , factors that end up giving rise to the color of the rainbow.
In Optical Physics, scattering is defined as the separation of light into various spectral components, with different frequencies. This phenomenon occurs due to the difference in refractive indices that separate the media.
Another phenomenon that can be explained from dispersion is the way in which the colors of the sky are formed . During the day, the sky is blue , but at dusk, it becomes reddish . This happens because the molecules of the air, when hit by sunlight, scatter the blue and violet colors with great intensity, however, the human eyeis little sensitive to violet color. When the afternoon comes, the Earth is more inclined and, therefore, the sun’s rays travel a much greater distance in the atmosphere. Therefore, blue and violet light, which are scattered with greater intensity, are not perceived by the observer’s eyes, but red and orange light are, causing us to perceive the sky in a red-orange hue.