0 1 okta or less, but not zero 2 oktas 3 oktas 4 oktas 5 oktas 6 oktas 7 oktas or more, but not 8 oktas 8 oktas Sky obscured by fog and/or other meteorological phenomena Sky partially obscured by fog and/or other meteorological phenomena Scattered Broken Few Cloud cover is indiscernible for reasons other than fog or other meteorological phenomena, or observation is not made Cirrus (Ci) Cirrocumulus (Cc) Cirrostratus (Cs) Altocumulus (Ac) Altostratus (As) Nimbostratus (Ns) Stratocumulus (Sc) Stratus (St) Cumulus (Cu) Cumulonimbus (Cb) No CH clouds Cirrus fibratus, sometimes uncinus, not progressively invading the sky Cirrus spissatus, in patches or entangled sheaves, which usually do not increase and sometimes seem to be the remains of the upper part of a cumulonimbus; or cirrus castellanus or floccus Cirrus spissatus cumulonimbogenitus Cirrus uncinus or fibratus, or both, progressively invading the sky; they generally thicken as a whole Cirrus (often in bands) and cirrostratus, or cirrostratus alone, progressively invading the sky; they generally thicken as a whole, but the continuous veil does not reach 45 degrees above the horizon Cirrus (often in bands) and cirrostratus, or cirrostratus alone, progressively Invading the sky; they generally thicken as a whole; the continuous veil extends more than 45 degrees above the horizon, without the sky being totally covered Cirrostratus covering the whole sky Cirrostratus not progressively invading the sky and not entirely covering it Cirrocumulus alone, or cirrocumulus predominant among the CH clouds No CM clouds Altostratus translucidus Altostratus opacus or nimbostratus Altocumulus translucidus at a single level Patches (often lenticular) of altocumulus translucidus, continually changing and occurring at one or more levels Altocumulus translucidus in bands, or one or more layers of altocumulus translucidus or opacus, progressively invading the sky; these altocumulus clouds generally thicken as a whole Altocumulus cumulogenitus (or cumulonimbogenitus) Altocumulus translucidus or opacus in two or more layers, or altocumulus opacus in a single layer, not progressively invading the sky, or altocumulus with altostratus or nimbostratus Altocumulus castellanus or floccus Altocumulus of a chaotic sky, generally at several levels No CL clouds Cumulus humilis or cumulus fractus other than of bad weather, or both Cumulus mediocris or congestus, towering cumulus (TCU), with or without cumulus of species fractus or humilis or stratocumulus, all having their bases at the same level Cumulonimbus calvus, with or without cumulus, stratocumulus or stratus Stratocumulus cumulogenitus Stratocumulus other than stratocumulus cumulogenitus Stratus nebulosus or stratus fractus other than of bad weather, or both Stratus fractus or cumulus fractus of bad weather, or both (pannus), usually below altostratus or nimbostratus Cumulus and stratocumulus other than stratocumulus cumulogenitus, with bases at different levels Cumulonimbus capillatus (often with an anvil), with or without cumulonimbus calvus, cumulus, stratocumulus, stratus or pannus CH CM CL Clear Liquid water Supercooled liquid water Mixed phase Optically thick ice Optically thin ice Multilayered ice Cloud not visible owing to darkness, fog, duststorm, sandstorm, or other analogous phenomena CH clouds invisible owing to darkness, fog, blowing dust or sand, or other similar phenomena, or because of a continuous layer of lower clouds CM clouds invisible owing to darkness, fog, blowing dust or sand, or other similar phenomena, or because of continuous layer of lower clouds CL clouds invisible owing to darkness, fog, blowing dust or sand, or other similar phenomena Missing value