Group Cumulus.
1. Cumulus minor (Plate [43]). Small cumulus.
Cumulus clouds so small as to present the appearance of rounded lumps, no definite pyramidal form or flattened base. Cu. Mi.
2. Cumulus major (Plates [44] and [45]). Large cumulus.
Characterized by a flattened base and rounded clear-cut upper surfaces. Cu. Ma.
3. Cumulo-nimbus (Plates [49] to [52]). Storm cloud.
Characterized by the expanded, anvil-shaped, or disc-shaped top, cirrifying at its edges.