https://www.theverge.com/2018/7/6/17540708/noctilucent-night-shining-clouds-methane-climate-change-photography

Strange clouds that glow in the night sky are getting easier to see — and it could be because of all the methane we’re pumping into the atmosphere, a new study says.

The bad news is that methane is a greenhouse gas that’s contributing to global warming. But the good news is that more methane means that more of us might get a chance to see these stunning, night-shining — or noctilucent — clouds, according to the study, which was published this week in the journal Geophysical Research Letters.