CHANCE OF STORMS: NOAA forecasters estimate a 65% chance of G1-class geomagnetic storms on Jan. 5th as Earth moves into a stream of fast-moving solar wind. The source of the wind is a large hole in the sun's atmosphere. Arctic sky watchers should be alert for aurorason Thursday night. Free: Aurora Alerts
A NEW METEOROLOGICAL PHENOMENON? We've all heard of the wind chill factor. It's how wind makes cold air feel even colder. Inside the Arctic Circle, Lights over Lapland tour guide Oliver Wright has discovered a new meteorological phenomenon: auroras make cold air feel ... not so bad. "Last night," he explains, "the air temperature in Abisko, Sweden, was -35 C when these auroras appeared."
"As the auroras intensified and developed into multiple coronas, our guests were less bothered by the cold," Wright observed.
"Coronas" are auroras that materialize directly overhead, creating a rippling spray of light centered on the zenith. They tend to occur during periods of strong magnetic unrest, and they are widely considered to be the most beautiful manifestation of Northern Lights.
More coronas are possible tonight as a quickening stream of solar wind buffets Earth's magnetic field. Observers around the Arctic Circle may find that they don't feel nearly as cold as they actually are. Stay tuned.
FANTASTIC SUN PILLAR: When the air gets very cold, fantastic things can happen to the setting sun. Peter Rosén of Stockholm, Sweden, witnessed one of them on Jan. 5th. "With freezing temperatures, thermometers reading -10°C, and ice crystals floating in the air, we got a fantastic sun pillar at sunset this afternoon."
Sun pillars are caused by ice in the air. Plate-shaped crystals ice fluttering down from cirrus clouds catch the rays of the setting sun and spread it into a vertical column.
"Watch a leaf or piece of paper flutter and wobble as it falls," says atmospheric optics expert Les Cowley. "Ice crystals in the air wobble, too, and this smears the sun's reflection into a vertical line."
All around the world, the atmosphere is cold enough 5 to 10 km high to produce these ice crystals. That means sun pillars can be seen anywhere. However, the odds of sighting one improve in cold places like Sweden. Residents of the north should be alert for these beautiful pillars as winter unfolds.
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