> Jeff, thanks for the information. How is the measurement made? > Well, back in the old days ;) it was done by the forecaster...now many have automated that process. That will be defined in the report: The abbreviation âAUTOâ is included in any METAR/SPECI which includes observations recorded without human input. Where no cloud is detected in such a report, the letters âNCDâ will be included and in most cases, when a cloud base recorder does not detect any cloud and the recorded visibility is 1000 metres or less, the phrase âCLD:SKY MAY BE OBSCâ will be included as a RMK.(remark) So, automated weather stations will use either LIDAR or a ceilometer currently and earlier (years) attempt at automation used an optical drum recorder... Hope this helps, Jeff Jeff Weber Unidata User Support http://www.unidata.ucar.edu Ticket Details =================== Ticket ID: LSK-251795 Department: Support IDD Priority: Normal Status: Open
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