From the article that I read on physics classroom website on rainbow, rainbow is formed with red on the top and violet on the bottom because violet refracts more, and has a smaller angle of deviation and red refracts less and has a bigger angle of deviation. So the red light rays come out of the water droplet steeper than do the blue rays. This steepness requires you to look higher up in order to see the red part of the rim.
Here is also an explanation I saw of my question on PhysicsSE. But the answer to that question doesn't really answer my particular question about the concepts of the formation of rainbow.
- Water droplets being so small, and the width of rainbow so big, how then is the whole rainbow still shown in ROYGBIV, but not composed of rainbows of smaller width, the colors of each too shown in the order of ROYGBIV?
- What is described in the PhysicsClassroom seems to only work for the very top portion of the entire rainbow that is horizontal. I don't see how it would work for the vertical portion, the part where the rainbow starts from the ground. At this portion, the observer does not have to change his/her angle of viewing in relative to the ground in order to see the two (violet and red) extremes of the color band.
please attach a picture of a single droplet and how rays from the Sun comes in and out of the droplet and into the observer's eye.