How are rainbows formed. I know it’s about refraction from water droplets, but shouldn’t you see many tiny rainbows instead of one big one.
In: Physics
> **shouldn’t you see many tiny rainbows instead of one big one**
True there are many droplets, but there’s only one light source (typically). The Sun.
So each droplet forms a slightly different Sun-droplet-observer angle, which results in a slightly different apparent color for each droplet. The combined effect of this multitude of different colors is a rainbow.
Probably the [best explanation of rainbows](https://www.youtube.com/watch?v=6Hl7BLXq5vA) I’ve ever seen. Not ELI5 though, more like college physics level.
[Found a 1 minute explanation as well](https://www.youtube.com/watch?v=uRmdZVvzMzQ), closer to ELI5 level.
Our eyes are picking up all the tiny rainbows and merging them into one consistent pattern as each drop is in a slightly different place each one has a small bit of the puzzle – https://youtu.be/usEcoMirsu8
TIL that a rainbow would look different to each person depending on their angle of viewing. Thanks to everyone who attempted to ELI5
Take a thousand 1cm x 1cm mirrors (raindrops) and arrange them into a grid on the wall. Stand in front of it wearing a gay pride shirt. You will only see one rainbow. Your pal standing next to you will see one slightly different rainbow.
Everyone is talking about the droplets, it it’s solely about the light source and your position relative to it. You see it when there’s is spray inside near a bright lamp and get a smaller rainbow.
Rainbows are a bit like a mirror, as others have said, they’re unique to everyone because of positions, colour perception in your eye etc.
Ok, having learned something from all the info here, here’s my attempt to ELI5 it: (I may be mixing up refract and reflect, but I’ll just pick one). Maybe ELI9,since we do need to talk about angles.
Sun hits a raindrop and light refracts off in all sorts of directions. If the drop is at a specific angle to you in relation to the sun, you will see that refracted light as a color. So for this example, lets say that angle is 45 degrees.
So for this example, you have the sun behind you and look directly away from it. We’ll call that point zero degrees. Now we know that a raindrop at 45 degrees from there will refract color to you. 45 degrees to the left you see red, 45 degrees up you see red, 45 degrees to the right you see red. Since every point 45 degrees from the center is showing you red, it forms a red circle around the center. You don’t see the bottom of the circle because the ground is there and you can’t see rain under the ground.
As for the other colors, each color in the rainbow is created by a slightly different angle. So at 44 degrees you see orange, 43 yellow, etc.
It’s because the sun is very far away.
When a single raindrop refracts the light, it does it in a straight line, red on top, violet on bottom. The angle this line comes out of the droplet depends on the angle between the sun, the drop, and you.
Because the sun is very far away, we can consider it a “point source”. That means all the light is coming from the exact same point in space. The light source has no width or height, just a single dot of light.
Now, since we can consider the sun a point source, think about the shape of a rainbow. It’s a circle, though usually cut off by the horizon. So we have a circle and a point, draw some lines between them and you have a cone!
What’s happening here is that when water droplets refract the light, the angle the light comes out is relative to the angle it comes in. Since the sun is a point source, the angles add up to form a circle! Think about the cone we drew from the sun to the rainbow. Light comes from the point, travels to the base edge at an angle, then hits a water droplet that refracts it at the *opposite* angle. This places the point of observation somewhere *inside* the cone, which is why you can only see rainbows if the sun is behind you!
yknow how you can take a hose with one of those fancy nozzles and put it on mist and see a rainbow?
its like that except the whole sky
You *would* see many tiny rainbows, if you could look at it from many perspectives simultaneously.
Latest Answers