Rainbows, Shadows, and the Physics of Light

Zooming along above the clouds (window seat, of course) I was thinking about rainbows. Not sunshine and lollipops kind of rainbows, but light refracted and reflected through water droplets in the air.

I read a riddle once that posed the question, “If you look at the very center of the arc of a rainbow, what will you see?

The answer is, “Your shadow.”

From aircraft I’ve had the pleasure of seeing full circle rainbows several times, and sure enough, there’s the shadow of the plane in the middle. I often wonder if the plane were banked a the right angle, if I would be able to see the shadow of the plane, within that light of the sun shining through the windows of the plane, with the silhouette of my head in the light of the window in the shadow of the plane in the middle of the rainbow!

A little while later, I look to my right out of the window (flying from ATL to EWR I was looking east) and there was a shadow of the plane in the middle of a bright bullseye-rainbow! Rainbows are visually pretty large; more than 80 degrees of your field of view. This was much smaller, and as the clouds reflecting the rainbow came closer, the shadow of the plane grew HUGE. Really, really a cool sight to see. It looked exactly like an archery target.

Definitely not the 40º (x2) span of a rainbow. Which cause me to look it up when I got home. I found a picture of something similar, but not as spectacular.  There is a picture below; it’s called a glory (or pilot’s glory, or solar glory), and I don’t quite understand why you see a glory sometimes (I’m sure I’ve seen them before and just didn’t realize what it was) and sometimes a rainbow. I will figure it out one of these days. I’m currently thinking it has to do with the distance from you point of view to the point of refraction. Far away = rainbow, closer = glory.

One of these day’s I’ll talk about sun dogs, which I’ve seen twice in my life, but one time it was like looking at a crystal fortress in the sky.


Posted in Daily Miracles, Physics, Random Interesting Thoughts