That rainbow really struck me. Certainly, I've seen rainbows, but this one was unusually intense in color and nearly complete. It wasn't a full circle, but I usually think of rainbows as fading off on one side. After I resumed driving, I kept peeking at the rainbow and it started to fade. I was lucky to see it full and intense for the brief time it was there.
In reality, the rainbow was more nearly circular. This image was taken as three exposures on my cell-phone camera, then merged with Photoshop Elements 4 using a perspective merge and advanced blending. This explains the kink near the peak of the rainbow and the spreading of the curve (divergence from circular). Initial attempts to merge the images had major discontinuities in the sky and rainbow, so I kept playing with the Photoshop options.