Rayleigh Scattering
Definition and meaning of Rayleigh Scattering in chemistry.
Rayleigh scattering is the elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation.
In more detail
This phenomenon occurs when light travels through transparent solids and liquids, but it is most prominently observed in gases. The intensity of Rayleigh scattering is inversely proportional to the fourth power of the wavelength. This means that shorter wavelengths, such as blue and violet light, are scattered much more strongly than longer wavelengths, such as red and yellow light. This differential scattering is responsible for the blue color of the daytime sky, as well as the reddish hues of sunrise and sunset. When sunlight passes through a thicker layer of the atmosphere at dawn or dusk, most of the blue light is scattered out of the direct beam, leaving predominantly red and orange light to reach the observer.
Key facts
| Field | Physical Chemistry |
|---|---|
| Dependence | Inversely proportional to wavelength to the fourth power |
| Type | Elastic scattering |
| Particle Size | Much smaller than the radiation wavelength |
The sky appears blue because molecules of nitrogen and oxygen in the atmosphere scatter short-wavelength blue sunlight in all directions through Rayleigh scattering.
Frequently asked questions
Why is the sky blue?
The sky is blue because gas molecules in the atmosphere scatter blue light from the sun more effectively than other colors due to Rayleigh scattering.
How does it differ from Mie scattering?
Rayleigh scattering applies to particles much smaller than the wavelength, whereas Mie scattering applies to particles roughly the same size as the wavelength.