National Geographic : 1925 Aug
~idsu 'a L .il\ r'" bg~q"$k ~:a: .1 ~:~ ~~, <>r ~ rnotograpn ny t. j . lienry ALTO-CUMULUS: UNDULATED) TYPE Alto-cumuli are the highest of the cumulus family. They usually gather some two miles up, in great crowds of small and medium-sized patches, partly shadowed, partly gleaming white. and produce some of the most striking of the cloud effects. It is they that form the prettiest "dappled skies." Shadows usually serve to distinguish small alto-cumuli from cirro-cumuli. Photograph by W. S. Davis STRATO-CUMULUS "Large globular masses or rolls of dark cloud, often covering the whole sky, especially in winter. Generally strato-cumulus presents the appearance of a gray layer irregularly broken up into masses, of which the edge is often formed of smaller masses (see upper part of lower illustration, page 186), often of wavy appearance, resembling alto-cumulus."