noctilucent

Noctilucent, meaning "night shining," refers to luminous clouds that appear in the mesosphere. These clouds are the highest in Earth's atmosphere, typically forming at altitudes between 76 to 85 kilometers (47 to 53 miles). They are most visible during twilight hours in the summer months at latitudes between 50 and 70 degrees. Noctilucent clouds are composed of tiny ice crystals that form on dust particles, likely originating from meteoroids or volcanic eruptions.

The appearance of noctilucent clouds is characterized by their silvery or bluish-white glow against the darkening sky. They can take on various forms, including wispy filaments, ripples, or wave-like structures. Their formation is thought to be linked to specific atmospheric conditions, including very cold temperatures in the mesosphere and the presence of water vapor. Scientists study these clouds to gain insights into the dynamics and composition of the upper atmosphere, as well as potential influences of climate change. Their appearance has also been observed on other planets, such as Mars.