It answers in fact fully to the E. word rack, Indicating atmospheric Nebulosity; hence Ragnarok is very approp.
"The Elder Eddas of Saemund Sigfusson; and the Younger Eddas of Snorre Sturleson"
Saemund Sigfusson and Snorre Sturleson
When she came close and looked in she beheld indistinct forms racing up and down to the figure of the dance, the silence of their footfalls arising from their being overshoe in "scroff"-that is to say, the powdery residuum from the storage of peat and other products, the stirring of which by their turbulent feet created the Nebulosity that involved the scene.
"Tess of the d'Urbervilles A Pure Woman"
Thomas Hardy
Speculated concerning the Milky Way, the Nebulosity of stars, the origin and growth of solar systems.
"Pioneers of Science"
Oliver Lodge