An eerie sight filled the sky over Tampa Bay, Florida, early yesterday morning: luminous clouds after a nearby SpaceX launch. But what exactly are noctilucent clouds?
Noctilucent clouds are extremely rare, very high clouds that are usually only visible in the summer night sky. They are mainly visible at sunrise or sunset (around the same time when the brightest stars become visible), looking wispy, luminous and bluish or silvery.
Noctilucent clouds form when water vapor freezes around dust particles. They appear to shine brightly in the night sky when illuminated by the sun shining on them from below the horizon.
Scientists say climate change is making noctilucent clouds more visible. That’s because increasing greenhouse gas emissions from human activities create more water vapor, which improves the visibility of noctilucent clouds. They were always there, we just couldn’t see them as often anymore.