'Crepuscular' is especially crunchy and satisfying, like eating whole crabs, but 'crepuscular light' itself isn't crunchy or crab-like at all, it's expansive and lucent and uplifting, and is known as 'Jacob's Ladder' to the uninitiated because it verges on the divine.
marvellous specimen which is more like the one I saw last night across the harbour. Unfortunately, I didn't have a camera to hand to catch it and send it to Mr Pretor-Pinney to add to his sprawling catalogue of cloud pictures sent in by other cloud appreciators.
Picking 'crepuscular' out of my teeth this morning, I wondered if it was related to the equally resonant 'crenellated'. I mused on the 'teeth' effect of the light and the castle walls ... but looking it up in the Shorter Oxford, as I eventually had to do, I discovered this:
crepuscular a. M17 [f. next + -AR; cf Fr crepusculaire.] 1 Resembling the twilight of morning or evening; dim, indistinct; not yet fully enlightened. M17. 2 Of or pertaining to twilight. M18. 3 Zool. Appearing or active by evening twlight. E19.
J. L. MOTLEY The state of crepuscular civilization to which they have reached.
Strange how unsavoury it sounds in the example - the exquisite pillars of light I saw are surely not a cousin of this dim, declining thing. But there you have it: 'crepuscular'. Thanks Gav.