About scattering in raindrops
- Regular scattering of light in raindrops results from both refraction and chromatic dispersion.
- Regular scattering occurs when light is scattered by particles that are much smaller than the wavelength of the radiation.
- Refraction occurs when light changes speed and direction as it passes from one transparent medium to another.
- Chromatic dispersion is the phenomenon where light separates into its various colours and becomes visible to a human observer.
- Scattering in raindrops obeys the laws of both reflection and refraction, commonly referred to as Snell’s law.
Here are three related descriptions of what causes scattering when visible light strikes a raindrop:
- When light of a specific wavelength strikes the surface and enters a raindrop its subsequent path depends upon the point of impact, and the refractive indices of water and air.
- When rays of light of a single wavelength strike a raindrop at different points, scattering is primarily determined by the angles at which they enter the droplet.
- The interaction between refraction and chromatic dispersion gives rise to the appearance of rainbow colours when parallel white light rays strike various points on the surface of a raindrop.