To understand the property of refraction through rainbows, first
you could think Raindrops as falling prism-like objects... The
same answer here - Refraction & Dispersion of light (Wikipedia &
Howstuffworks has a pretty good article on it...) These images
show the refraction and dispersion of light by raindrops (just
like an optical prism). But, it has a small difference from a
prism.. The refraction occurs twice inside a raindrop... (due to
the spherical shape I think so). For a typical rainbow, the
angle of refraction at which light would enter and exit the
raindrop is 40°-42° for colors in the order violet-red. This 2°
range is due to increasing wavelengths of different colors...
Howstuffworks shows a good comparison for the image below: When
A disperses light, only the red light exits at the correct angle
(42°) to travel to the observer's eyes. The other colored beams
exit at a lower angle, so the observer doesn't see them. The
sunlight will hit all the surrounding raindrops in the same way,
so they will