Atmospheric optics expert Les Cowley has seen almost every manifestation of ice in the sky that Nature can produce. He's not easy to impress. On Dec 6th, however, Michael Greenham of Magog, Quebec, photographed a display that impressed even Cowley:
"That is a great one," says Cowley.
"The air temperature was -1 C on a calm December morning," says Greenham. Sunlight hitting ice crystals in the air produced "very vivid sundogs and arcs in the sky."
"This magnificent ice halo display is bristling with rare arcs," says Cowley. "From top downwards we have a circumzenithal arc. Touching that is a bright and rare supralateral arc, often mistaken for the rarer 46 degree halo. Then we have a Parry arc, first recorded in 1820 by the famous Arctic explorer William Edward Parry. Touching the familiar 22 degree halo is a 'gull-wing' shaped upper tangent arc. Radiating outward from the sun at far left and right are very rare helic arcs."
Greenham spotted these halos in his front yard. Cowley knows another place to find them: "To best see halos like this choose a subzero day a few km downwind of a ski slope. Snow blowers make high quality halo forming crystals as well as snow!"
