Originally shared by Friends of NASA
Triple Rainbow over Norway
Rune: "I have seen a lot of rainbows, but not one like this, taken right after sunrise this morning."
Rainbow: an arc or circle of colors that appears in the sky opposite the sun. A rainbow is caused by the sunlight shining through raindrops, spray or mist
Credit: Rune Askeland
Location: Glesvær, Sotra, Norway
Image Date: August 26, 2018
How does that work? Optically speaking?
ReplyDeleteRainbows come at you from further back than the rainbow you're looking at. The sun is always behind you, and the rainbow origin is further behind the rainbow as you look at it. The direction that you're looking. It's the breaking apart of light as it enters, "bounces" off the back of the drop, and then exits towards you that "fractures" the light like a prism. Nearby groups of droplets all spray out the same - which is why (at a distance) they form a circle.
ReplyDeleteSo, if there were different groups of droplets receiving sunshine, each of the groups would form a different circle. That means that each of those rainbows are lit in groups. I suspect that behind the viewer, there are thick broken clouds radiating out beams of light in two or three groups to catch different droplet groups and form a different centre.
There are clear examples here of rainbows that don't share a centre (not all but some? I can't be sure, from this pic). Rainbows that share a centre are lit by the same beam but the droplet groups are further back. As an example, one group 2km away (clearer and smaller) and another one 3km away (larger and faded). Numbers are for illustration only.
James Hough ahh, I hadn't thought of multiple areas of rain allied with multiple breaks in the clouds behind. That makes sense, thanks.
ReplyDeleteRainbows arcs with different centers are generated by different sources. An example would be the sun in one case and the reflection of the sun off of a lake, for example.
ReplyDeleteAnd it appears legit. Most "fakes" get the outer rainbow wrong. The colours go in the opposite direction. The fakes often just clone the inner rainbow. Dead give-away.
ReplyDeleteFriends of NASA tends to be an extremely trustworthy source. :) Can't remember them ever posting anything fake.
ReplyDeleteUm...those arcs don't have the same center, and the observer's shadow is always at the center. (Sundogs are a different matter, but these aren't sundogs.)
ReplyDeleteUnless there's a strong secondary light source behind the observer (large, placid lake, perhaps?), I don't see any physical way to do that with a single exposure.