The Collaborative International Dictionary of English v.0.48:

Strato-cumulus \Stra`to-cu"mu*lus\, n. [Stratus + cumulus.]
   (Meteor.)
   Large balls or rolls of dark cloud which frequently cover the
   whole sky, esp. in winter, and give it at times an undulated
   appearance.
   [Webster 1913 Suppl.] Stratographic