Thunderstorm, slight or mod- 

 erate, without hail* but with 

 rain and/or snow at time of 

 observation. 



Thunderstorm, slight or mod- 

 erate, with hail* at time of 

 observation. 



Thunderstorm at 

 lime of observa- 

 tion. 



99 



'Hail, small hail, soft hail. 



Thunderstorm, heavy, without 

 hail* but with rain and/or 

 snow at time of observation. 



Thunderstorm combined with 

 duststorm or sandstorm at 

 time of observation. 



Thunderstorm, heavy, with 

 hail* at time of observation. 



(St 



Fs). 



Code Cloud type 



Stratus or Fractostratus 



1 Cirrus (Ci). 



2 Cirrostratus (Cs). 



3 Cirrocumulus (Cc). 



4 Altocumulus (Ac). 



Use code for SIGNIFICANT cloud layer 



Table 2.— CLOUD TYPE CODE 



Code Cloud type 



5 Altostratus (As). 



6 Stratocumulus (So). 



7 Nimbostratus (Ns). 



8 Cumulus or Fractocumulus (Cu or Fc). 



9 Cumulonimbus (Cb). 



CLOUD TYPES 



Compiled by the U. S. Weather Bureau to aid in the interpretation and coding of cloud observations. 



Family "A" High Clouds: Cirrus (Ci), Cirrocumulus (Cc). Mean lower level, 6,000 meters, 



20,000 feet. 



Code 1 



CIRRUS -> 



(Note. — Further illustrations and descriptions 

 of clouds are contained in U. S. Weather Bureau 

 Circular S, Second Edition, "Manual of Cloud 

 Forms and Codes for States of the Sky." This 

 publication may be obtained by cooperating 

 marine observers at U. S. Weather Bureau Port 

 Offices and Marine Centers.) 



Code 1 



CIRRUS -> 



Hi: Filaments or strands of cirrus scattered 

 and not increasing (often "Mares' Tails"). 



H. O. 607 



175 



