cirrostratus

noun

1. A principal high-level cloud type appearing as a whitish veil, usually fibrous but sometimes smooth, which may totally cover the sky and which often produces halo phenomena.

   “[page 99] Cirro-stratus. […] Horizontal or slightly inclined masses, attenuated towards a part or the whole of their circumference, bent downward, or undulated, separate, or in groups consisting of small clouds having these characters. […] [page 103] The cirro-stratus precedes wind and rain, the near or distant approach of which may sometimes be estimated from its greater or less abundance and permanence.”