Mississippi State University Weather

Scattering 101

The Colorful Atmosphere

As a lover of all things weather, one weather phenomenon in particular (that I love) are the clouds and beautiful blue skies that we see here in Mississippi on clear, calm days. Many people may wonder why the sky is blue. Why not, red, or green? It is a simple, yet complex idea dealing with a term called scattering. Keep in mind that the human eye can only see a small portion of what the sun is giving off from the electromagnetic spectrum. Our eyes can only see the visual part of that spectrum and with that comes different wavelengths represented by a multitude of colors. When the sun comes up every morning, the incoming solar radiation is in reach with Earth’s atmosphere, it is scattered in all different directions. Blue wavelengths are scattered much more efficiently and they are shorter which is why the sky looks blue.


Science Made Simple. Digital image. N.p., n.d. Web. 29 Oct. 2015. <Http://www.sciencemadesimple.com/img_sky/horiz.jpg>.

Now there are two terms to define more specifically that help to explain why the sky is blue and why the clouds are white; Rayleigh scattering and Mie scattering. As discussed earlier, the sky appears blue because of the sunlight that is reflected off of different molecules. Rayleigh scattering better defines this idea because the scattering of light off of the molecules of the air gives us the blue sky. For Mie scattering, it does not necessarily depend upon the wavelength but it gives off the white glare that we see around the sun when a lot of particles are in the air. Rayleigh scattering is the more dominant of the two because of its favor towards shorter wavelengths. The water droplets that make up the cloud are much larger than the parcels in the air and they do not depend on wavelength, so they are overshadowed by the blue wavelength leaving them with a white-grayish tint.


The Natural Environment. Digital image. N.p., n.d. Web. 29 Oct. 2015. <https://laulima.hawaii.edu/access/content/group/2c084cc1-8f08-442b-80e8-ed89faa22c33/book/chapter_2/scatter.htm>.

Sunrise & Sunset

For sunrises and sunsets, this concept is a little different. Starkville is known for its beautiful sunsets and sunrises, almost everyone has either put a picture on Twitter or Instagram of the sun setting. As the sun lowers in the sky, the atmosphere at that  becomes much thicker and these wavelengths have to scatter through it. Shorter wavelengths have a harder time doing that, so longer wavelengths can penetrate through. Blue and violet wavelengths are scattered back into space due to their shorter wavelengths, while red and orange wavelengths make it through the thicker layer making the sky beautiful. Smog and ash can also enhance the coloring of the sunset and sunrises. The atmosphere has a unique way of working and the science behind it makes it more intriguing that what the human eye can only see.  ~Caroline Ritter


Photo taken by Caroline Ritter on October 24, 2015 during the Run For Wishes 5k put on by Chi Omega at Mississippi State University