|Halos over Bulgaria imaged at Cherni Vrah (Black peak), Vitosha Mountain near Sofia by Nikolay Stoilov. ©Nikolay Stoilov, shown with permission.
|Two types of ice crystal produced this display.
Hexagonal plate crystals generated the bright circumzenithal arc (CZA).
The down curving much fainter arc touching the CZA is a supralateral arc produced by sun rays passing between the side and end faces of horizontal column crystals.