<- CIRROSTRATUS 



Code 2 



H8 : Cirrostratus not increasing and not cover- 

 ing the whole sky; cirrus and cirrocumulus 

 may be present. 



If cirrocumulus is present, the cirrostratus 

 must predominate to satisfy the requirements 

 of Code 2 . If the cirrocumulus predominates, 

 the sky would be coded as Code 3. 



<- CIRROCUMULUS 



Code 3 



H9: Cirrocumulus alone or cirrocumulus with 

 some cirrus or cirrostratus, but the cirro- 

 cumulus being the main cirriform cloud 

 present. (Cirrocumulus may be present in 

 Code 1 to Code 2. 



Family "B" Middle Clouds: Altocumulus (Ac), Altostratus (As). Mean upper level, 6,000 meters, 

 20,000 feet; mean lower level, 2,000 meters, 6,500 feet. 



<- ALTOSTRATUS 



Code 5 



M 1 : Thin altostratus (semitransparent every- 

 where) through which the sun or moon can be 

 dimly seen. A sheet of this cloud resembles 

 thick cirrostratus from which it is often de- 

 rived without any break; but halo phenom- 

 ena, sun pillar, etc., are not seen in cirro- 

 stratus, and the sun or moon appears as 

 though shining through ground glass and does 

 not cast shadows. 



178 



H. O. 607 



