Which type of light scattering causes the reddish-orange colors observed during sunsets?

The reddish-orange colors observed during sunsets are primarily caused by Rayleigh scattering. This phenomenon occurs when light interacts with small particles or molecules in the atmosphere, primarily those of gases like nitrogen and oxygen. As sunlight passes through the atmosphere, especially at lower angles during sunrise and sunset, the shorter wavelengths of light (blue and violet) are scattered in all directions, while the longer wavelengths (red, orange, and yellow) tend to pass through more directly. This scattering effect makes the longer wavelengths more prominent, giving the sky its warm hues during these times.

Mie scattering, on the other hand, involves larger particles in the atmosphere, such as dust or water droplets, and generally contributes to the scattering of all wavelengths more evenly, leading to grayish or white skies rather than the distinct reds and oranges seen at sunset. Brillouin scattering is a rare phenomenon associated with acoustic waves and the scattering of light with sound waves, which does not apply to the colors observed during sunsets. Similarly, Raman scattering involves inelastic scattering where energy is transferred between light and molecules, resulting in frequency changes that are not responsible for the vivid colors of sunsets. Thus, Rayleigh scattering is the correct explanation for the beautiful shades of red and orange that characterize sunset scenes.