We have all seen what happens when some people run across double rainbows out in the wild. I don’t even what to know what that dude would have done had he happened on a twin rainbow. A double rainbow is when there are two separate rainbows over the top of each other. A twin rainbow is when one splits in to two separate bows.
Google software engineer Iman Sadeghi performed research on the physics of rainbows at the University of California, San Diego for his doctorate. He created software that was able to simulate rainbows and the way they occur in nature. The software created the geometry of a raindrop and the reflection of the light that creates the colors we see in a rainbow.
In a double rainbow, light that hits the water drops is reflected twice before emerging creating the double effect. In a twin rainbow, there are two types of raindrops involved with small round drops and then fatter, flat drops called burgeroids thanks to their resemblance to hamburgers. The burgeroids shift light in one direction and the small drops produce a separate rainbow.