IRIDESCENT STORM

 IRIDESCENT STORM CROWN AT SUNSET OVER GREAT PLAINS, OKLAHOMA-USA

For a few minutes, the cloud’s edge turns into a thin ribbon of neon—quiet color sitting on top of a serious thunderhead.

That glow is cloud iridescence: sunlight gets diffracted by a tight layer of tiny, similarly-sized droplets or ice crystals near the cloud’s top (often in a smooth “cap” layer), spreading light into pastel greens, oranges, and blues. It’s usually brief because the droplet sizes change fast as the storm grows.