"Okta" is the unit of measurement to describe the amount of cloud cover.
Okta is reported in eighths of the celestial dome covered by all clouds visible. The codes represent:
0: 0/8, the complete absence of cloud;
1: 1/8 or less, but not zero;
2: 2/8;
3: 3/8;
4: 4/8, half of the sky is covered;
5: 5/8;
6: 6/8;
7: 7/8 or more, but not 8/8;
8: 8/8, sky is completely covered;
9: Sky obscured by fog and/or other meteorological phenomena;
/: Cloud cover is indiscernible for reasons other than fog or other meteorological phenomena, or observation is not made.
https://windy.app/blog/okta-cloud-cover.html
"Okta" is the unit of measurement to describe the amount of cloud cover. Okta is reported in eighths of the celestial dome covered by all clouds visible. The codes represent: 0: 0/8, the complete absence of cloud; 1: 1/8 or less, but not zero; 2: 2/8; 3: 3/8; 4: 4/8, half of the sky is covered; 5: 5/8; 6: 6/8; 7: 7/8 or more, but not 8/8; 8: 8/8, sky is completely covered; 9: Sky obscured by fog and/or other meteorological phenomena; /: Cloud cover is indiscernible for reasons other than fog or other meteorological phenomena, or observation is not made.
https://library.wmo.int/viewer/68695/?offset=3#page=514&viewer=picture&o=bookmark&n=0&q=