NOCTILUCENT CLOUDS STILL GOING STRONG
NOCTILUCENT CLOUDS STILL GOING STRONG: Usually, August 1st is the beginning of the end for noctilucent clouds (NLCs) in the northern hemisphere. Weather conditions at the top of Earth's atmosphere shift in August, making it more difficult for meteor-seeded ice crystals to form. Soon thereafter, NLCs fade from view. As August begins in 2018, however, noctilucent clouds are still going strong. Yesterday, Vesa Vauhkonen photographed a bright display over Rautalampi, Finland:
"On the morning of August 1st, some very beautiful noctilucent clouds appeared over Lake Konnevesi--the best I've seen in many years," says Vauhkonen.
A similar display appeared over the Talkeetna Mountains of Alaska. "They were the best noctilucent clouds I've ever seen, extremely bright," reports eyewitness Tempy Larew.
What's happening? Previous studies have shown that NLCs sometimes intensify during solar minimum. The idea is that extreme UV rays from the sun dim during solar minimum, reducing a form of radiation that can split apart water molecules. More water in the mesosphere means more noctilucent clouds. Solar minimum conditions are in effect now as the sun has been without spots for 34 of the past 36 days. Perhaps noctilucent clouds are thriving as a result.
A similar display appeared over the Talkeetna Mountains of Alaska. "They were the best noctilucent clouds I've ever seen, extremely bright," reports eyewitness Tempy Larew.
What's happening? Previous studies have shown that NLCs sometimes intensify during solar minimum. The idea is that extreme UV rays from the sun dim during solar minimum, reducing a form of radiation that can split apart water molecules. More water in the mesosphere means more noctilucent clouds. Solar minimum conditions are in effect now as the sun has been without spots for 34 of the past 36 days. Perhaps noctilucent clouds are thriving as a result.
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