St compared with As

(Section 2.3.8.6.3)

Stratus is distinguished from Altostratus by:

• The  outline of the Sun not being blurred; that is the disc or partial disc of the Sun is discernible
• Absence of shading in thin Stratus when viewed towards the Sun (Altostratus always has shading)
• Precipitation in the form of drizzle or snow grains (Altostratus has rain and ice pellets); snow can occur with both clouds