# Follow up to an Interesting Photo: In Flight

To all,

Recently we discussed this interesting photo:

In the Shadow of a Plane

Thanks to all who commented on our previous post for the help in understanding what is generating the color rings, but I still wanted a little more understanding. I took the liberty to dig a little deeper, meaning reading beyond a wikipedia article, and I found that a NASA satellite imaged the same phenomenon: NASA photo. The NASA satellite photographed a glory just like this photo only the diameter was miles larger. I also found three other informative discussions: Here, here, and here(p145).  Thanks to all who commented on our previous post for the help in understanding what is generating the color rings, but I more understanding.

Lets try to nail this thing down.

What I gathered is that it is created by the water droplets in the air, not due to the plane itself. The same color rings can be seen around your head from the top of really tall mountains, then it is called specter of the Brocken. This is the science as I understood it: when the droplets are the right size, Mie Scattering takes place in all the little water droplets. This is a very complicated phenomenon involves diffraction, surface effects of the droplet, and I would imaging refraction too. This scattering of light from all those millions of droplets averages to create the colors rings. Scientists in the 70’s used Mie Scattering theory calculations to predict the intensity of the rings.

Optical Glory

But, if you prefer, don’t take my word for it and read for yourself. I only dug a little and read these websites I linked to. I would like to thank those individuals who composed their work on the subject before me.

One more mystery solved: I was confused as to why the rings were centered where they were. Why not the back of the plane? Well, the center of the rings is always located on the straight line between the sun and observer, so you can guess where I was sitting on the plane. It moves with the observer just like a normal rainbow. Speaking of normal rainbows, the importance of the water droplets in our color rings makes since because it is after rain when we see our old favorite rainbows.

Wow! This was a much bigger subject than I originally expected when I first thought it was an interesting photo. Thanks for going on this ride with me. If anyone has any extra thoughts or corrections, speak your peace. While were at it, let me know if anyone has seen other interesting in flight phenomenon!

All the Best,
Ben Washington

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