A cloudy night sky adds drama to the Lunar Eclipse event in the San Francisco Bay Area. I was fortunate to be able to grab a few shots whenever a break in the clouds afforded me the opportunity. This one image caught me by surprise when I saw the blue halo as the images taken within minutes of either side of this image had no such feature.

Could this effect be caused by light diffraction? I am hypothesizing that the cloud layer (invisible in this image) may have acted as a 'filter' thus blocking out IR.