Rayleigh Scattering is the scattering of light by particles that are smaller than the wavelength of light that hits the particle. When light hits a particle that is small the scattering angle of the light is dependent on the wavelength. As illustrated in the following picture I made. In this picture below white light is scattered from a particle indicated by the black circle. Longer wavelengths, i.e. red and yellow wavelengths, are scattered the least but shorter wavelengths, such as blue, are scattered at greater angles from the original path of light.
How has everyone seen this effect? This is the reason why some eyes are blue. The particles that are in the iris are smaller than in other types of eyes and this leads to blue wavelengths being scattered off of the iris. If you would like to learn more about what other physical effects lead to other eye colors I invite you to check out wikipedia's article on eye color. So next time you see anyone with beautiful baby blues, you can thank Rayleigh Scattering. (Photo by paul+photos = moody's on Flickr)
The most important phenomenon that can be explained by Rayleigh Scattering is the color of the sky. This picture, taken by kevindooley on Flickr, is a perfect example of Rayleigh Scattering. You can see that closer to the sun the light is redder, then the light fades to yellow as you get farther away from the sun, and then finally to blue. This is due to the scattering angle of the light that is hitting the particles in the atmosphere. This gradient from red to yellow to blue is present throughout the day around the disk of the sun but the colors do not spread out enough to be noticed until the sun is close to the horizon during sunset.
This is just one of the many physical effects you can observe on a daily basis. If you have any questions about Rayleigh Scattering feel free to ask and I will gladly answer them.
JPLittleton
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I teach high school physics and I think this explanation is great! This blog seems to be exactly the kind of thing I've been looking for. It takes a real world phenomenon and explains the physics behind it in simple terms that can be understood by the average person. I plan to use this explanation when I talk about light in my low level physics class. Thank you so much for doing this and keep up the good work!
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