Atmospheric optics expert Les Cowley comments on the display: "Rare halo arcs come in clusters. They are a sign of large numbers of near perfect hexagonal ice crystals drifting in the air. In this case, the crystals were nearby and called 'diamond dust.'"
"Many rare arcs get called after their discoverers," says Cowley, who points out the named arcs in Ganchevska's picture: "First above the sun is a faint ‘V’, the mysterious Moilanen arc, named after the Finland halo expert. Next we have the well-known 22 degree halo and the gull-winged shaped tangent arc. Above that the rare Parry arc first recorded in the Arctic in 1820 by the famous explorer. Yet further up is a colourful and rare supralateral arc. Yet another picture shows two greater rarities, a Tape arc (Parry supralateral) named after halo expert Walter Tape and a helic arc."
"There are arcs waiting out there for a discoverer," says Cowley. "Get looking!"