Here is an interesting photo I captured while in flight. I love looking out of the window during flights because you can see a lot of very interesting things, and this one I had not seen before. It it the shadow of the airplane on an adjacent cloud. This is neat in itself, but not very curious. The curious part is the ring of color bands like a rainbow surrounding the shadow. As a note to those concerned, my phone was on airplane mode, so no interference created here. You’ve got to obey those flight attendants!
A note also to any skeptics, I have not altered this photo in any way other than cropping. This is merely what the camera on my phone captured. Here a two more pictures to confirm it was not a fluke. I did not crop these photos, so the shadow appears a little further away.
In the photos the color rings where always with the shadow and the shadow appears “on top” of the rings. Also, the rings only show when projected on the cloud. With these things in mind, I conclude that the color rings are not an effect created by the camera or with my window, but the color bands are actually on the nearby clouds.
Lets try and understand why these rings of light were created.
My first thought brought me to the diffraction or bending of light as it passes around an object. As an example, the Greeks made their columns a little wider at the center so that they would appear of constant diameter. This is because as light diffracts around the column it is pulled inward making them look a little smaller at the center, see photos below. In the photo on the right, the light diffracts around the window frame making it look like there is a hole. But this has nothing to do with a rainbow ring, so we need more information.
My next thought brought me back to introductory physics class and when we learned that light is both a particle and a wave. The canonical experiment is single or multiple slit diffraction experiments. As light passed through a very narrow slit, it would bend and create this line of alternating colors like a rainbow. When it passed through a hole it would make rings like we see here. This is good, we are making progress. (For those who did not take that introductory physics class, I am sorry, but I don’t really have the space here to get you up to speed.)
Two things are left unexplained. The plane is not a hole, but a dot (compared to the sun), and the plane is not round, but plane shaped. If I remember correctly, diffraction happens just the same with a dot instead of a hole. This makes sense because the light will still bend. But why did the weird shape of the airplane make perfect circles of light.
I am still a little perplexed. Can any readers help fill in the holes of understanding regarding this interesting photo? Is my thinking so far correct or is something totally different at play here?