Cu cover
Whether cumulus forms, and how much of the sky it covers.
Cu cover shows whether thermals will make cumulus, and how much of the sky it will cover, in oktas (eighths of the sky).
How to read it
Section titled “How to read it”A few oktas of cumulus is what most pilots hope for: the clouds mark the thermals and the air between them sinks less. No cumulus means a blue day, where you have to find the thermals without markers. A sky that fills up shades the ground and the thermals weaken.
Cloud amount is drawn as a colourless wash on purpose: no amount of cloud is better or worse in colour terms.
What goes into it
Section titled “What goes into it”Cumulus forms when thermals rise high enough to reach the level where their moisture condenses. See Working height and cloud base.