At first, the dark band in between seems so counterintuitive, but then your realise rainbows don't create extra light, so it has to come from somewhere. Alexander's Dark Band is the empty husk left behind after a rainbow is born.
That doesn't explain the gay frogs, at all.
So I don't know if I got a picture, but I was at a local beach right at sunset, and we had this moment where, for like just a moment, the entire valley behind us lit up with rainbows. Not a double rainbow, but like 5+ deep 'double' rainbows. It was utterly surreal.
Can somebody explain this image? If you had raindrops in only those four positions, this might make sense, but I think there are more than four static drops and thus angles.
Edit: staring at it helped. Anything that hits your eyes in a certain way comes from above a certain angle and has to have traveled and been refracted in a certain way, anything below a different angle is the opposite. Hence the opposite order to the rainbows and the difference in intensity from the difference in length of the path (which loses more light on each change in direction).
Not exactly correct, but close enough for my brain to stop trying to figure out.
More info can be found here: https://old.atoptics.co.uk/rainbows/ord34.htm
So how do triple rainbows work?
Light bounces around and exits a raindrop in many different directions. This graphic illustrates the first(brightest) two that hit your eye, but there will be a third, fourth, etc in decreasing brightness.
Also, the tertiary rainbow is directly around the sun, which is hard to see because of, you know, the sun.
AAAAAAA DOUBLE RAINBOW
All the way!
