Plate 21-24 of 1921 cloud chart. 21. Strato-cumulus or alto-stratus sheet,
slightly mammulated.... 22. Strato-cumulus, evaporating scaly type.... 23.
Cumulus and strato-cumulus below, thin alto-stratus above. 24. Lenticular
alto-stratus. Uper, standing clouds topping S wind; lower left, standing cloud
in lee of Mt. Washington during NW gale; lower right, conditions unknown.