Usually, August 1st is the beginning of the end for noctilucent clouds in the northern hemisphere. Weather conditions at the top of Earth's atmosphere shift in August, making it more difficult for summertime wisps of water vapor to crystallize around specks of meteor smoke. As August begins in 2018, however, noctilucent clouds are still going strong. Just this morning, Vesa Vauhkonen photographed a bright display over Rautalampi, Finland:

NLCs over Rautalampi, Finland
© Vesa Vauhkonen
NLCs over Rautalampi, Finland
"Night-shining clouds over the lake of Konnevesi were very beautiful--the best ones 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," says eyewitness Tempy Larew.

NLCs over the Talkeetna Mountains of Alaska
© Tempy Larew
NLCs over the Talkeetna Mountains of Alaska
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.