Sunlight from upper left beams into a simulated water droplet. The light is refracted and reflected by the droplet. Shorter wavelengths of light are refracted more, causing a dispersion of colours (most obvious in the diverging rainbow beam at lower left). This image uses simulated light beams and the refractive indices of water for the respective colours. The dispersion (separation of colours) is less than normally shown because the graphic strives for accuracy.