Table 10. Type of middle clouds 

 Symbol f M — Clouds of types Altocumulus, Altostratus, and Nimbostratus 



Code 



fig- 

 ures 



9 

 X 



Technical language specifications 



No Cm clouds 



Altostratus translucidus. 



Altostratus opacus or Nimbo- 

 stratus. 



Altocumulus translucidus at a 

 single level. 



Patches of Altocumulus translu- 

 cidus (often lenticular), contin- 

 uously changing and occurring 

 at one or more levels. 



Altocumulus translucidus in 

 bands, or one or more layers 

 of Altocumulus translucidus or 

 opacus progressively invading 

 the sky; these Altocumulus 

 clouds generally thicken as a 

 whole. 



Altocumulus cumulogenitus (or 

 cumulonimbogenitus) . 



Altocumulus translucidus or 

 opacus in 2 or more layers, or 

 Altocumulus opacus in a single 

 layer, not progressively invad- 

 ing the sky, or Altocumulus 

 with Altostratus or Nimbo- 

 stratus. 



Altocumulus castellanus or floc- 

 cus. 



Altocumulus of a chaotic sky, 

 . generally at several levels. 



Clouds Cm not visible owing to 

 darkness, fog, blowing dust or 

 sand, or other similar phe- 

 nomena, or because of a con- 

 tinuous layer of lower clouds. 



Plain language specifications 



No Altocumulus, Altostratus or Nim- 

 bostratus. 



Altostratus, the greater part of which 

 is semitransparent; through this 

 part the sun or moon may be 

 weakly visible as through ground 

 glass. 



Altostratus, the greater part of which 

 is sufficiently dense to hide the sun 

 (or moon), or Nimbostratus. 



Altocumulus, the greater part of which 

 is semitransparent; the various 

 elements of the cloud change only 

 slowly and are all at a single level. 



Patches (often in the form of almonds 

 or fishes) of Altocumulus, the 

 greater part of which is semitrans- 

 parent; the clouds occur at one or 

 more levels and the elements are 

 continually changing in appearance. 



Semitransparent Altocumulus in 

 bands or Altocumulus in one or 

 more fairly continuous layers (semi- 

 transparent or opaque) progres- 

 sively invading the sky; these Alto- 

 cumulus clouds generally thicken 

 as a whole. 



Altocumulus resulting from the 

 spreading out of Cumulus (or Cu- 

 mulonimbus). 



Altocumulus in two or more layers 

 usually opaque in places and not 

 progressively invading the sky; or 

 opaque layer of Altocumulus not 

 progressively invading the sky; or 

 Altocumulus together with Alto- 

 stratus or Nimbostratus. 



Altocumulus with sproutings in the 

 form of small towers or battle- 

 ments, or Altocumulus having the 

 appearance of cumuliform tufts. 



Altocumulus of a chaotic sky gen- 

 erally at several levels. 



No Altocumulus, Altostratus or Nim- 

 bostratus visible owing to darkness, 

 fog, blowing dust or sand, or other 

 similar phenomena, or more often 

 because of the presence of a con- 

 tinuous layer of lower clouds. 



18 



