To understand how ‘night-shining’ clouds form, scientists made one themselves
A high-altitude explosion shows how water vapor can cool air to rapidly form ice crystals
![noctilucent cloud as seen from International Space Station](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2021/03/030321_MT_cloud_feat.jpg?fit=1030%2C580&ssl=1)
Noctilucent clouds (seen here from the International Space Station) shimmer high in the dark sky after sunset, when sunlight from beyond the horizon illuminates ice crystals in the upper atmosphere.
International Space Station, NASA’s Johnson Space Center