The optical physics are too complex (and dull) to explain in mere words however Google is indeed the best chance of finding some decent piccies. Other optical goodies to watch out for are "Sun Dogs" which are often seen from the ground when the sun's rays are refracted by ice crystals in sheets of thin cirrus producing a bright patch or even a small section of a rainbow.
(The refraction is always observed at a radial distance of 22.5 degrees from the sun)
Another cool sight is a moonbow (I kid you not) so check out
http://www.sundog.clara.co.uk/rainbows/moonbow.htm
Complete halos around the moon are quite common when there is a thin even cirrus sheet and the following link gives you some idea of what such an event looks like
http://www.sundog.clara.co.uk/halo/circmoon.htm
cool
