Why is it that you only see rainbows in the morning or afternoon? I am thinking this is because of the way the sun's rays are. Ima

MIKE MOSS SAYS:      You're on track with your insight, in the sense that if you imagine a particular ray of light that runs directly from the sun through the back of your head and out to where the shadow of your head is located (the "anti-solar point"), a primary rainbow (the one that is most prominent and commonly seen) is formed along a circle that exists at a 42 degree angle outward from that location. Therefore, if the sun is more than 42 degrees above the horizon, that entire circle is below the horizon and no rainbow is observed. The closer the sun is to the horizon, after sunrise or toward sunset, the greater the portion of that circle (at most, the arc that comprises almost the upper half) may be visible.

You'll find a very nice web site about rainbows at this address:

http://www.atoptics.co.uk/bows.htm