Appendix B. Glossary of Terms and Abbreviations Used* 
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 Term            Meaning and description                                  
                                                                              
 5c grid         5x5° (latitude x longitude) boxes between latitudes 50N
                  and 50S, 5x10 for latitudes 50-70, 5x20 for latitudes
                  70-80, 5x40 for latitudes 80-85, and 5x360 for 85-90.

 actual amount   Fraction of the sky covered by a cloud, visible or not. 
 
 all reports     All reports regardless of whether they are light or dark. 

 awp             Amount-when-present.  The average fraction of the sky 
                  covered by a cloud type when it is present, whether 
                  it is visible or not.
 
 dark reports    Reports for which illuminance criterion is not met (IB=0).

 ECR             Edited Cloud Report.  Synoptic cloud reports screened 
                  and edited for cloud code consistencies and written 
                  as the 56-character report described in Table 9.

 ECRA            Archive made up of edited cloud reports.

 extended code   The synoptic code extended beyond the usually allowed 
                  values of 0-9 to allow CL=10 to represent Cb, CL=11 to 
                  represent fog and CM=10,11,12 to represent Ns cloud.

 f               Frequency of occurrence.  For a cloud type it is the
                  fraction of weather observations in which the cloud
                  type is present, whether it can be seen or not.

 light reports   Reports for which illuminance criterion is met (IB=1).

 NOL             Non-overlapped; refers to method for determining upper
                  level cloud amounts.

 ROL             Random overlap; refers to method for determining upper
                  level cloud amounts.

 total reports   Reports suitable for total cloud analyses (and clear sky,
                  fog, and precipitation); either all reports (the entire
                  ECR data set) or light reports only.

 type reports    Reports in which cloud type information is given (Nh>/=0
                  and CL>/=0.  These may be light, dark, or all reports.

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 * Terms not shown here may be defined in Table 1, 2, 4 or 9.