RECORD-SETTING NOCTILUCENT CLOUDS: Last night (Sunday, June 9th) sky watchers in the San Francisco Bay Area of California witnessed an extraordinary display of noctilucent clouds (NLCs) above the city lights. This marks one of the lowest-latitude sightings ever of NLCs. The clouds are typically confined to latitudes above +55 N, yet San Francisco is at +38 N. Mid-latitude observers should remain alert for NLCs tonight. Read the article below for observing tips.
HUGE OUTBREAK OF NOCTILUCENT CLOUDS: Over the weekend, a huge outbreak of noctilucent clouds (NLCs) occurred as tendrils of frosted meteor smoke were sighted in Europe and the USA as far south as Oregon, Utah and California. "What a surprise," says Andrew Robb of Beaverton OR. "It's been almost 10 years since I've seen NLCs here in Oregon. They're back!"
Robb took the picture, above, just after sunset on June 8th. "NLCs stretched the length of the whole horizon," he says. "Their rippling waves and other structures were fascinating."
NLCs are Earth's highest clouds. Seeded by meteoroids, they float at the edge of space more than 80 km above the planet's surface. The clouds are very cold and filled with tiny ice crystals. When sunbeams hit those crystals, they glow electric-blue.
Normally, NLCs are confined to polar regions, but this year people are seeing them at middle latitudes, too. On June 8th and 9th the clouds appeared in California, Utah, Minnesota, Wisconsin, Washington, Montana, Iowa, Oregon and Maine. Electric-blue ripples also blanketed much of Europe. This is what sunrise over Poland looked like on June 9th:
"It was such a beautiful display of noctilucent clouds," says photographer Marek Nikodem of Szubin, Poland.
Why are noctilucent clouds suddenly so bright? Previous studies have shown that noctilucent clouds sometimes intensify during solar minimum. Solar minimum conditions are in effect now as the sun has been without spots for 22 consecutive days--a situation that may favor the frosting of meteor smoke high above Earth.
At present, no one can predict exactly when noctilucent clouds will appear. Last night's display, however, suggests that more of the clouds may be in the offing even at mid-latitudes. Observing tips: Look west 30 to 60 minutes after sunset when the sun has dipped below the horizon. If you see luminous blue-white tendrils spreading across the sky, you may have spotted a noctilucent cloud.
Realtime Noctilucent Cloud Photo Gallery
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