QUIET WITH A CHANCE OF FLARES: Solar activity has been low for the past three days, but the quiet could be shortlived. There are currently three sunspot groups (3536, 3539, 3540) with unstable 'beta-gamma' magnetic fields. NOAA forecasters estimate a 45% chance of M-class flares and a 10% chance of X-flares on Jan. 8th. Solar flare alerts: SMS Text
THE POLAR VORTEX WOBBLED IN DECEMBER: Last month, sky watchers in Europe saw something rare and beautiful. A giant bank of polar stratospheric clouds (PSCs) escaped the Arctic Circle, and for more than a week they filled skies with rainbow color as far south as Italy. In the Italian commune of Sanfrè (latitude +45N), Pablo Javier Lucero was able to photograph the clouds at all hours of the day:
"Utterly incredible!" says Lucero. "I first saw the clouds at sunset on Dec. 22nd. After talking with a friend of mine, Jorgelina Alvarez, a meteorologist, we realized that these clouds weren't ordinary iridescent clouds, but rather Type II polar stratospheric clouds. My surprise was gigantic."
Surprise is the correct reaction. Normally, Earth's stratosphere has no clouds at all. Only when the temperature drops to a staggeringly-low -85 C can widely-spaced water molecules assemble into icy polar stratospheric clouds. With colors that rival auroras, PSCs are considered to be the most beautiful clouds on Earth.
During the outbreak, Spaceweather.com received hundreds of photos of PSCs. Curiously, they all came from Europe. 100%. No photos were received from North America or Asia. Why not?
Amy Butler of NOAA's Chemical Sciences Laboratory has the answer: "The polar vortex can wobble like a top, and in December it was displaced towards Europe," she explains. "You can see this in the figure, below, from Zac Lawrence's website stratobserve.com."
Cold air normally contained over the poles was carried by the wobbling vortex to mid-latitudes. Purple and green contours in the figure show where temperatures were cold enough for Type I and Type II PSCs, respectively.
Since the December outbreak of PSCs, which ended around Christmas, the polar stratosphere has warmed more than 10 degrees. Butler says this is probably the result of "a strong planetary wave breaking in the stratosphere." Wave energy warmed the air and dispersed the rainbow-colored clouds.
It could happen again, though; there's plenty of winter ahead. As January unfolds, the polar stratospheric vortex is still tilted toward the mid-latitudes of Europe. If the stratosphere cools, PSCs could re-appear over populated areas. You can monitor the situation with daily temperature reports right here on Spaceweather.com.
Recommended: Amy Butler writes a great Polar Vortex Blog for NOAA. Check it out!
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VALENTINE'S CRYSTAL BEAR AND ROSE: Valentine's Day is coming. Looking for a far-out gift? This Crystal Bear and Rose flew to the stratosphere onboard a cosmic ray research balloon on Dec. 17th:
You can have it for $129.95. The students of Earth to Sky Calculus are selling space bears to support their high-altitude ballooning program. Each one comes with a greeting card showing the ursine astronaut in flight and telling the story of its journey to the edge of space and back again.
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education
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