22 degree lunar ice halo above our street (Te Weka Street, Timaru) 12 May 2009
This night, I had seen a smaller 'corona' around the moon about 10:00pm when coming home. The smallish 'rainbow' ring around the moon being far more common, didn't pull my interest. But I kept an eye out during the night and finally, spotted the big one at about 2:20am in the morning. I photographed it for the next 40 minutes, un till the cloud thickened and the effect disappeared.
Strange... I seem to be seeing ice halos everywhere now
So at last I have found my first halo all by myself - well worth staying up half the night. Even so, I still think it is quite rare to see such large rings around the moon. First, the moon needs to be in full phase to show greatest effect.. Then, at the same time the cloud must form it's certain shaped ice crystals to create the effect.
Thinking about it, the weather has only a dozen short periods to 'get it right' each year, compared to a solar event, which can happen on any day. To further lessen the chances of seeing a Lunar Halo, we don't spend that long looking up into the night sky either. We do need our sleep!
On the other hand, while the occurrence is much rarer under full moon, it is more likely to draw our attention, should we be out an about - we all like to look up at the moon.