Night-shining ‘noctilucent’ clouds have crept south this summer
An uptick in atmospheric moisture may be fueling clouds that catch the sun’s rays after dark

SHINE ON Noctilucent clouds that catch sunlight after dark are showing up farther south than usual this year. Scientists are studying the upper atmosphere to figure out why.
Matthias Süßen/Wikimedia Commons (CC BY-SA 4.0)