This is a very important point. You are always in between the sun and the center of the rainbow circle, the sun is at your back. A normal rainbow has a lighter area of sky under it. White is the reflected color under the rainbow. Dark, or no added reflected light is over the top, over the red.
Yellow light is in the middle of a rainbow.
A warm magenta is barely visible on top of the red on a strong rainbow. Also, yellow will appear again under the magenta on a strong rainbow. If you make your own rainbow, with a small spray of water, you don't see the green, white will take it's place. Red is on the outside of the main rainbow and on the inside of the second rainbow, the second rainbow is separated by 15 degrees actual. It refracts light to you from the start of the other 180 degrees of polarized light, like rotating the prism.