Wave forms again are indicated by the addition of the word undatus.
Group Alto Clouds. Divisible into nine species.
1. Alto-stratus. High stratus.
A uniform veil of cloud showing no details of structure except local variation in density in patches. Rarely dense enough to completely hide the sun, or even the full moon. A. S.
2. Alto-stratus maculosus (Plate [30]). Mackerel sky.
Characterized as numerous nearly equal and small lenticular patches ranged on a level and about equi-distant from each other. A. S. Mac.
3. Alto-stratus fractus (Plate [34]).
Patches and bits of cloud of irregular shape, but resembling broken bits of a level sheet. A. S. Fr.
4. Alto-strato-cumulus (Plate [32]).
Intermediate between alto-stratus and alto-cumulus. A. S. Cu.