The age of the noctilucent cloud is upon us. Night-shining clouds are historically rare, beautiful formations of shimmering ice crystals hanging in the upper atmosphere that were only visible in the northern parts of the world in years past. They’ve been steadily creeping south for four decades though, so this could be the year you peep this unique phenomenon from your backyard.
While noctilucent clouds are often present in the upper atmosphere, they aren’t typically visible unless atmospheric conditions are exactly right. Traditionally, peak season for seeing these swirling night clouds is late June through the end of July, and while they used to only be visible in the United States in Alaska and the very northernmost parts of the lower 48, global warming is making “visible NLCs” more common in more places. Yay?
What are noctilucent clouds?
First observed in 1885, noctilucent clouds, or NLCs, are clouds of ice that form at the edge of space, between 47 and 53 miles above ground. They usually appear as blue or white swirls only visible at the darkest hours in summer. NLCs are most visible between 50 and 60 degrees latitude, but recently, they have been becoming steadily brighter and moving as far south as Los Angeles, where people reported seeing them in 2019.
Why are noctilucent clouds more visible now?
Noctilucent clouds are invisible most of the time—the sky is too bright to see light reflecting off them during the day. But in the middle of the night, the lower part of the atmosphere is in earth’s shadow, while the upper atmosphere has light shining on it.
Small changes in the atmosphere can change these clouds significantly. Global warming has resulted in more water vapor in the atmosphere, and that has led to bigger noctilucent clouds that are visible over a wider area of the planet. As the world warms up more, we should see even more noctilucent clouds. (Again, yay?)
How you can see noctilucent clouds this summer
Night-shining clouds are only visible when the sky is clear of lower clouds, and at the darkest hours of the night. To see them, go outside at around midnight and look north. The best view requires an unobstructed, horizon-wide northern vista. The view is spectacular with the naked eye, but you might want a pair of binoculars to get a close-up view of the complexity of these clouds’ structures.
If you get lucky, you’ll see a few wisps of glowing white or gold relatively low in the horizon. If you get really lucky, the wispy clouds will grow and change color until electric blue, gold, and silver swirls, curls, and billows stretch across the entire sky.
We are in peak NLC season right now—that’s mid-June through July—but which nights might feature the formations can’t be predicted more than a few hours in advance. In the past you had to go out every night and hope, but sky-watching fans across the world are using technology to share NLC information and alert one another about the appearance of these elusive cloud formations.
Subscribe to these social media groups for advance news of noctilucent clouds
Anyone to the east of you is going to see the NLCs first, and fans of the phenomenon are only too happy to alert you that it’s coming. You can subscribe to the Noctilucent Clouds Alerts twitter feed, where users upload pictures of occurrences and send out the word; join a similar group on Facebook; or follow #noctilucent on twitter or instagram. I assume all of these feeds go absolutely bat-crap crazy when the night clouds appear. Here’s hoping we all get the chance to check out this strange, wondrous phenomenon this summer.