| Code/Flag Figure |
Description |
Status |
|
0
|
Observing rules for base of lowest cloud and cloud types of FM 12 SYNOP and FM 13 SHIP apply
|
Operational
|
|
1
|
First non-Cumulonimbus significant layer
|
Operational
|
|
2
|
Second non-Cumulonimbus significant layer
|
Operational
|
|
3
|
Third non-Cumulonimbus significant layer
|
Operational
|
|
4
|
Cumulonimbus layer
|
Operational
|
|
5
|
Ceiling
|
Operational
|
|
6
|
Clouds not detected below the following height(s)
|
Operational
|
|
7
|
Low cloud
|
Operational
|
|
8
|
Middle cloud
|
Operational
|
|
9
|
High cloud
|
Operational
|
|
10
|
Cloud layer with base below and top above the station
|
Operational
|
|
11
|
Cloud layer with base and top below the station level
|
Operational
|
|
12-19
|
Reserved
|
Operational
|
|
20
|
No clouds detected by the cloud detection system
|
Operational
|
|
21
|
First instrument detected cloud layer
|
Operational
|
|
22
|
Second instrument detected cloud layer
|
Operational
|
|
23
|
Third instrument detected cloud layer
|
Operational
|
|
24
|
Fourth instrument detected cloud layer
|
Operational
|
|
25-61
|
Reserved
|
Operational
|
|
62
|
Value not applicable
|
Operational
|
|
63
|
Missing value
|
Operational
|