;
ICAO : The height above the ground or water of the base of the lowest level of cloud below 6 000 metres (20 000 feet) covering more than half the sky. ; Canada: A ceiling is the lesser of the following: the height above ground or water of the base of the lowest layer of cloud covering more than half of the sky, or the vertical visibility in a surface-based layer which completely obscures the whole sky. Therefore, a ceiling exists at the height of the first layer for which a coverage symbol of BKN or OVC is reported. The existence of a vertical visibility constitutes an obscured ceiling. ;
EASA States: The height above the ground or water of the base of the lowest layer of cloud below 6 000 m (20 000 ft) covering more than half the sky. ; United Kingdom : The height above the ground or water of the base of the lowest layer of cloud below 6000 m (20000 ft) covering more than half the sky. ; United States : The height above the Earth's surface of the lowest layer of clouds or obscuring phenomena that is reported as broken, overcast, or obscuration, and not classified as thin or partial. == See also ==