...
Please note that Ceiling generally differs from Cloud Base Height, sometimes substantially so, because of the requirement, for Ceiling, of >50% cover (compared to >1% for Cloud Base Height). This partly explains why, on the example plots below, high Ceiling values are focussed on tropical areas, where the cloud cover from the convection is often below the 50% threshold at lower levels. Related documentation, on Convective Cloud Top (and Cloud Base Height) can be found here.
...