noctilucent cloud

Meanings

1. Clouds characterized by their electric-blue or silvery-white, wispy streaks, filaments, or ripples high in the twilight sky; Earth's highest clouds, glowing at the edge of space, serving as indicators of climate change, showing increased frequency and visibility linked to human activities like methane emissions and rocket launches; maintain unique formation in frigid summer mesosphere, from ice crystals on meteoric dust, providing scientists with high-altitude atmospheric window into changes in upper atmospheric water vapor and dynamics.

Etymology

The clouds were studied extensively by German astronomer Otto Jesse, who was the first to photograph them in 1887, and seems to have been the one to coin the term noctilucent cloud.