On a cold winter day thousands of years ago, the local inhabitants of northern Europe may have looked into the sky to see a spectacle much like the one on the cover. Perhaps, they became convinced of the presence of a deity. Such is the dazzling power of an ice crystal display, and it has been proposed that the Prophet Ezekiel’s vision of a wheel within a wheel was a complex ice crystal display not too dissimilar to our cover this month.

The magnificent and complex ice crystal display illustrated here was photographed by Walter Tape in Antarctica, and can be found on the cover of his book entitled Atmospheric Halos (American Geophysical Union, 1994). It illustrates some of the many possible rings, arcs, pillars, and other optical phenomena that often greet the observant.

The innermost circle of reflected light is called the 22° ring, and is very common. Such 22° rings or fragments are visible in most parts of the world, and perhaps up to 200 days a year or more. This is a ring refracted through the prism-like ice crystals formed in the stratosphere or even near …