The appearance of a reddish-orange hue in the sky during or after rainfall is primarily attributable to the scattering of sunlight by atmospheric particles. This phenomenon occurs when larger particles, such as those found in rain clouds or dust, are present in significant concentrations. These particles preferentially scatter shorter wavelengths of light (blue and green) away from the observer’s line of sight, allowing longer wavelengths (red and orange) to dominate the visual spectrum.
This scattering effect, known as Mie scattering, differs from Rayleigh scattering, which explains the blue color of the sky on clear days. Mie scattering is more pronounced when particle size is comparable to or larger than the wavelength of light. The consequence is a richer, more saturated display of sunset or sunrise colors, which can be particularly vivid when these conditions coincide with precipitation. The intensity of the coloration depends on the density and composition of the atmospheric particles, as well as the angle of the sun.
