Mie Scattering

Mie scattering describes how light and other electromagnetic waves are redirected when they encounter a sphere whose size is on the order of the wavelength of the radiation. Unlike Rayleigh scattering, which applies only to particles much smaller than the wavelength and produces a simple angular dependence, Mie theory solves Maxwell’s equations for the full range of sizes, accounting for complex interference between light that passes around the particle and light that penetrates and emerges from it.

The phenomenon matters because it determines the colour, intensity, and polarization of light after it has interacted with common suspensions such as droplets in fog, aerosols in the atmosphere, or pigment particles in paints. By analyzing the scattering pattern one can infer the size distribution and composition of the particles, a capability that underlies techniques ranging from climate monitoring to medical diagnostics.

Mie scattering reappears wherever spherical particles are present in an optical path: in clouds and rain forming the white glare of the sky, in industrial processes that monitor spray nozzles with lasers, in laboratory instruments that size colloidal beads, and even in astronomical observations of dust around stars. Its predictive power comes from a mathematically exact solution, making it a cornerstone concept for anyone working with light interacting with small objects.