What Is Noctilucent Cloud?
Rare, glowing, silvery-blue clouds seen at twilight, far higher than any normal cloud. In technical terms: Ice clouds forming near the summer polar mesopause at about 76-85 km, visible when illuminated by the Sun below the observer's horizon; the highest clouds in Earth's atmosphere.
Also called: NLC, Polar Mesospheric Cloud
Noctilucent Cloud In Plain English
Rare, glowing, silvery-blue clouds seen at twilight, far higher than any normal cloud.
The Technical Definition
Ice clouds forming near the summer polar mesopause at about 76-85 km, visible when illuminated by the Sun below the observer's horizon; the highest clouds in Earth's atmosphere.
