Table AIV-7.—WMO CODE 1690
WMO CODE 1690
hBhBhB - Height of lowest level of turbulence.
hihihi - Height of lowest level of icing.
hfhfhf - Altitude of 0°C isotherm.
hththt - Altitude of cloud layer or mass.
hxhxhx - Altitude to which temperature and wind refer.
hshshs - Height of base of cloud layer or vertical visibility.
Code figures 000 to 099 are in single-unit increments, code figures 100 to 990
are in ten-unit increments.
Code figures are the number of 30-meter units of height or altitude. This is
nearly identical with the U.S. convention of reporting heights or altitudes in
hundreds of feet. A few examples follow:
code 000 = <30 meters = <100 feet
code 001 = 1 30-meter increment (30 meters), used as 100 feet
code 002 = 2 30-meter increments (60 meters), used as 200 feet
code 099 = 99 30-meter increments (2970 meters), used as 9,900 feet
code 990 = 990 30-meter increments (29,700 meters), used as 99,000 feet
Table AIV-8.—WMO CODE 2700
WMO CODE 2700
N - Total cloud cover.
Nh - Amount of cloud in a layer.
Ns - Amount of individual cloud layer with genus indicated by C.
N' - Amount of cloud with base below station level.
Code
Eights
Tenths
0
0
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
0
1
2-3
4
5
6
7-8
9
10
9
Sky obscured
/
Sky condition not observed
AIV-14
