Dispersion, or scattering, occurs when light or other waves encounter particles or irregularities in a medium, causing the waves to change direction. This phenomenon can be observed in various contexts, such as when sunlight passes through the atmosphere, resulting in the blue color of the sky. Different wavelengths of light scatter at different rates, which is why shorter wavelengths, like blue, scatter more than longer wavelengths, like red. This principle is also responsible for the colorful effects seen in rainbows and the way light behaves in materials like glass or water, where it can bend and spread out.