CODE TABLES 



The form of predominating cloud is the genus which is observed to 

 cover the largest portion of the sky at the time of observation. All 

 species or special forms of each cloud genus will be counted in deter- 

 mining the total amount of sky covered by that genus. 



FORM OF PREDOMINATING CLOUD 



Codes for the forms of clouds and states of the sky, lower, middle, 

 and upper levels, are as follows: 



I. LOWER CLOUDS C^ 



0. No lower clouds 22 



L Cumulus of fine weather 22 



2. Cumulus heavy and swelling, without anvil top 22 



3. Cumulonimbus 23 



4. Stratocumulus formed by the flattening of cumulus clouds 23 



5. Layer of stratus or stratocumulus 23 



6. Low broken up clouds of bad weather 24 



7. Cumulus of fine weather and stratocumulus 24 



8. Heavy or swelling cumulus, or cumulonimbus, and stratocumulus 24 



9. Heavy or swelling cumulus (or cumulonimbus) and low ragged clouds 



of bad weather 24 



II. MIDDLE CLOUDS C^ 



0. No middle clouds 25 



1. Typical altostratus, thin 25 



2. Typical altostratus, thick (or nimbostratus) 25 



3. Altocumulus, or high stratocumulus, sheet at one level only 25 



4. Altocumulus in small isolated patches; individual clouds often show 



signs of evaporation and are more or less lenticular in shape 26 



5. Altocumulus arranged in more or less parallel bands, or an ordered 



layer advancing over the sky 26 



6. Altocumulus formed by a spreading out of the tops of cumulus 27 



7. Altocumulus associated with altostratus or altostratus with a partially 



altocumulus character 27 



8. Altocumulus castellatus, or scattered cumuliform tufts 28 



9. Altocumulus in several sheets at different levels, generally associated 



with thick fibrous veils of cloud and a choatic appearance of the sky „ . 29 



III. UPPER CLOUDS Ch 



0. No upper clouds 29 



1. Cirrus, delicate, not increasing, scattered and isolated masses 29 



19 



