Vancouver Sun Halo
Yesterday, on my way to the East Van Show and Shine, my friend Eli pointed out a circular rainbow around the sun. Not something you see every day, and since we both had our cameras we took some photos. Someone suggested that this phenomenon is called a sun dog or sundog (Wikipedia), but I think it is actually a sun halo. A sun dog is a ‘mock sun’, or a bright point of light similar to the sun. I this case, it’s a complete circular halo around the sun and looks like a rainbow. There are some references to these things here and here.
Update (May 29): After posting on a forum, it turns out this phenomenon is called a sun halo. It is seen when thin cirrus clouds are present high in the atmosphere on a sunny day. Light refracts off ice crystals and creates the effect. More info here: 22° halo at Wikipedia, NASA.