<- CUMULONIMBUS 



Code 9 



L9: Cumulonimbus having a clearly fibrous 

 (cirriform) top, often anvil-shaped, with or 

 without cumulus, stratocumulus, or stratus, 

 or "scud." 



By extension at various levels, cumulonim- 

 bus often produces cirrus, altocumulus, or 

 stratocumulus clouds. Therefore, cumulo- 

 nimbus may coexist with clouds that should 

 be coded, when detached from the parent 

 cloud, Code 1 or 2 If these clouds are not 

 detached, they should not be coded separately. 



Cumulonimbus clouds generally produce 

 showers of rain or snow and sometimes of 

 hail, and often thunderstorms as well. 



If the whole of the cloud cannot be seen 

 the fall of a real heavy shower is enough to 

 characterize the cloud as a cumulonimbus. 



Table 3.— CLOUD COVER CODE 

 Code Amount of sky covered in i 



No clouds. 



1 Less than 1 and 1. 



2 2 and 3. 



3 4. 



4 5. 



5 6. 



6 7 and 8. 



7 9 and 9 plus. 



8 10. 



9 Sky obscured. 



Table 4.— VISIBILITY CODE 



[Use range-finder readings of known landmarks if 

 possible.] 



186 



H. O. 607 



