Someone needs to give her a book:
Rainbows are created by refraction. Sunlight passes through the dropplets
of water, and it splits apart into whatever colors of light make up white
light (i.e. red, orange, yellow, green, blue, indigo, violet), and this
is what you see. In fact, rainbows are spherical. If you were to look down
down from a plane at one, you'd see a circle of colored light. You can
do this yourself with a garden hose, and spraying a fine mist of water.
Spray the mist down to the ground, and look down from above. Of course,
you have to be facing away from the sun for this to work. Pretty neat
though...
