Ceiling is a new output parameter introduced with cycle 43r1. It gives the height in metres (m), above the level of the model orography, of the base of the lowest cloud layer covering more than 50% of the sky (more than 4 oktas). This follows the definition of ceiling used in aviation (ICAO), except that we also represent situations of >6000 m (~20000 ft). Plots below show an example of a ceiling forecast for the whole Globe and for Europe.
