cre·pus·cu·lar | /kri-ˈpə-skyə-lər/
In modern parlance, crepuscular is generally understood to mean relating to or resembling twilight. It comes to us from the Latin crepusculum, which specifically refers to evening twilight – in turn, probably stemming from the adjective creper, meaning dim, obscure, or uncertain. Its sibling term for the dawn twilight is diliculum, which has itself dimmed into obscurity.
Given it looks like a blend of creep, pus, and peculiar, crepuscular shouldn’t really be such an attractive word, yet it rolls off the tongue redolent with the mysterious quality of dusk. If crepuscular doesn’t appeal, the archaic terms twitter-light, evenfall, and owl-light are each evocative alternatives. In Scotland, gloaming was popularised by Robert Burns and is still in common use. The French say entre chien et loup (between the dog and the wolf), when the facade of domesticity fades to reveal an untamed heart.
Zoologists use the term crepuscular to classify animals active during twilight, although these animals may also be vespertine (active in the night) and/or matutinal (active in the morning). Most mosquito species are primarily crepuscular as are many predatory mammals such as bears. Some desert-dwelling animals are crepuscular in order to avoid the extreme temperature variations between night and day.
Crepuscular rays are sunbeams that radiate from behind irregular features on the horizon (usually clouds) just after sunset. These ‘god rays’ appear to radiate as an effect of perspective in the same manner the edges of a straight road appear to meet in the distance. On rare occasions, the beams can span the entire sky, reconverging towards the eastern horizon as anticrepuscular rays.
Introduction Aeolian Alpenglow Apricity Asperous
Benthos Crepuscular Crispate Crown shyness
Desire lines Dreich Endragoned Edgelands
Frondescence Fumarole Gluggaveður Gossamer
Karst Komorebi Lawrence Long acre
Machair Monkey’s wedding Moonglade
Psithurism Quartz Rakuyou Roaring forties
Snag Soft estate Specular, diffuse and pellucid
Spoondrift Steam fog Swash zone Sylvan