Ac compared with As

(Section 2.3.4.6.3)

Altocumulus is distinguished from Altostratus by:  

• Presence of thin plates, rounded masses, rolls, etc
• Possibly being thin enough to see the disc of the Sun or Moon (Altostratus will only reveal the position of the Sun or Moon or completely mask the Sun or Moon)
• Absence of the accessory cloud pannus
• Absence of any precipitation; Altostratus may produce rain, snow or ice pellets
• Absence of halo phenomena or irisation