A vocabulary of landscape — a landscape of words
1469 entries
noctilucent
Noctilucent means shining at night by light that comes from somewhere else. It is used almost entirely by noctilucent clouds, which form of ice at around 50 miles up and are lit by sunlight long after the sun has set at the ground. The word is also applied occasionally to other things that appear to glow after dark without producing their own light.
Etymology
The word is Latin, built from the words for night and shining, and it was coined in the 1880s when the clouds were first widely observed and needed a name. It means night-shining, not night-glowing, and the distinction matters, because the clouds are reflecting rather than emitting. The contrast is with nightglow, which really does emit.
Notes
The first widely reported sightings came in 1885, two years after Krakatoa, and were assumed at the time to be volcanic dust. They were not, though the eruption may have drawn attention to a sky people had not been examining. The clouds sit at the coldest place in the atmosphere and need temperatures below about minus 200 degrees to form.