Ceiling is a new output parameter introduced with cycle 43r1. It gives the height in metres (m) above surface of the base of the lowest cloud layer covering more than 50% of the sky (more than 4 oktas). This follows the definition of the ceiling used in aviation but it is not limited to clouds lower than 6000 m (20000 ft). Plots below show an example of a ceiling forecast for the whole Globe and for Europe.
