cumulo-

Also cumuli-; especially before a vowel, cumul-.

Origin of cumulo-

see origin at cumulus, -o-

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

There must be text-books on how to tell the cumuli from the cirrus.
Post-Impressions
Simeon Strunsky
Some are close-packed and dense, like cumuli; some are wispy or mottled, like cirri.
Curiosities of the Sky
Garrett Serviss
At sunset the thermometer was at 55°; the evening clear and calm, with some cumuli.
The Exploring Expedition to the Rocky Mountains, Oregon and California
Brevet Col. J.C. Fremont
The moon emerged from behind a cloud, touching with a delicate sepia some fleecy edge of cumuli.
The Record of Nicholas Freydon
A. J. (Alec John) Dawson
White clouds rising in the east gather into cumuli, with an increasing blackness along their lower portions.
The Desert World
Arthur Mangin

cumuli in Science

[kyōōm′yə-ləs]

Plural cumuli (kyōōm′yə-lī′)

A dense, white, fluffy cloud with a flat base, a multiple rounded top, and a well-defined outline. The bases of cumulus clouds form primarily in altitudes below 2,000 m (6,560 ft), but their tops can reach much higher. Cumulus clouds are generally associated with fair weather but can also bring rain when they expand to higher levels. The clouds' edges are well-defined when they are composed of water droplets and fuzzy when made up of ice crystals. See illustration at cloud.