Clouds from which Cumulus may form

(Section 2.3.9.5)

Cumulus is often preceded by hazy spots in the sky out of which the clouds develop.

Cumulus may evolve:

• From the development of Altocumulus castellanus (Cu congestus altocumulogenitus)
• From the development of Stratocumulus castellanus (Cu congestus stratocumulogenitus)
• By the transformation of Stratocumulus (Cu stratocumulomutatus)
• By the transformation of Stratus (Cu stratomutatus); this frequently occurs in the morning over land

Cumulus fractus of wet weather forms under Altostratus, Nimbostratus, Cumulonimbus or precipitating Cumulus (Cu fra altostratogenitus, nimbostratogenitus, cumulonimbogenitus or cumulogenitus).