INSTRUCTIONS T<D MARINE METEOROLOGICAL OBSERVERS 59 



Form of lower clouds (Cl). — The form of the lower clouds is 

 entered in the appropriate space on Form 12 10 A. The table below 

 gives the radio code numbers corresponding to the various forms of 

 lower clouds. 



Symbol Cl — Form of lower clouds 



Code 

 figures 



Form of clouds 



No lower clouds. 

 Cumulus of fair weathpr. 

 Cumulus Oarge, without anvil). 

 Cumulonimbus. 



Stratocumiilus (spread from cumulus). 

 Stratus or stratocumulus fin layerj. 

 Ragged low clouds of bad weather. 

 Cumulus and stratocumulus of fair weather. 

 Cumulus, large Cor cumulonimbus; and stratocumulus. 

 Cumulus, large (or cumulonimbus) and ragged low clouds of bad 

 weather. 



Form of middle clouds (Cm)- — The form of the middle clouds is 

 entered in the appropriate space on Form 1210A. The table below 

 gives the radio code numbers corresponding to the various forms of 

 middle clouds. 



Symbol Cm — Form of middle clouds 



Code 

 figures 



Form of clouds 



No middle clouds. 



Altostratus, typical thin. 



Altostratus, typical thick (sun or moon invisible), or nimbostratus. 



Altocumulus or high stratocumulus, single layer. 



Altocumulus, in bands, decreasing. 



Altocumulus, in bands, increasing. 



Altocumulus, spread out from cumulus. 



Altocumulus, with altostratus; or altostratus with parts resembling alto- 

 cumulus. 



Altocumulus castellatus (altocumulus in ragged fragments) . 



Altocumulus in several layers, generally with fibrous veils and chaotic ap- 

 pearance of sky. 



Form of upper clouds (Ch). — The form of the upper clouds is 

 entered in the appropriate space on Form 1210A. The table below 

 gives the radio code numbers corresponding to the various forms of 

 upper clouds. 



Symbol Ch — Form of wp-per clouds 



No upper clouds (cirrus type) . 



Citrus, fine, not increasing; scarce. 



Cirrus, fine, not increasing, plentiful but not a continuous layer. 



Cirrus, anvil. 



Cirrus, fine, increasing. 



Cirrus or cirrostralus increasing, below 45° altitude. 



Cirrus or cirrcstratus increasing, and reaching above 45° altitude 



Cirrostratus, veil covering entire sky. 



Cirrostratus, not increasing, and not covering whole sky. 



Cirrocumulus predominating, and a little cirrus. 



5672': 



