Atmospheric optics expert Les Cowley comments on the apparition: "There have been quite a few ellipticals seen in the last few weeks both in Europe and the US. Something strange [is happening] in all our skies!"
"These unusual ice halos are much smaller than the ordinary 22 degree halo encircling the sun or moon," Cowley continues. "In the 22 degree halo the ring is effectively made by light refracting through a 60 degree ice prism. The smaller elliptical halos need much narrower prisms and we think that six sided plate shaped crystals with very shallow pyramidal ends might do the work. The problem is that such crystals are unphysical and computer simulations using them do not predict the halo very well. An alternative is the wedge shaped sections of small snowflake-like crystals. Whatever their cause, they are rare and mysterious!"
The shower is subsiding now as Earth exits the debris stream.