© Andrew Robb
Last night, 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 and Utah. "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. Last night alone the clouds appeared in Utah, Minnesota, Wisconsin, Washington, Montana, Iowa, Oregon and Maine. Electric-blue ripples also blanketed much of northern to central Europe. This is what sunrise over Poland looked like on June 9th:
© Marek Nikodem
Comment: Photos of noctilucent clouds in Minnesota and Wisconsin: