Да, правилно сте се насочили. OKTAS e терминът, който се използва. Ето какво намерих по темата.

The cloud amount is defined as 'the proportion of the celestial dome which is covered by cloud.' The scale used is eighths, or oktas, with observers standing in an open space or on a rooftop to get a good view or panorama of the sky.

Complete cloud cover is reported as 8 oktas, half cover as 4 oktas, and a completely clear sky as zero oktas. If there is low-lying mist or fog, the observer will report sky obscured.

The reporter will also report the amount of each cloud level — 2 oktas of cumulus and 3 oktas of cirrus, etc.

The frequent passage of depressions across the United Kingdom means that the most commonly reported cloud amount is, not surprisingly, 8 oktas. A clear blue sky, i.e. zero oktas, is less common, as often on hot, sunny days, there are small wispy layers of cirrostratus or fine tufts of thin cirrus at high altitudes.