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bobtait replied the topic: How do we calculate cloud base?
I'm not sure exactly what you want with this question. The pilot never needs to 'calculate' the cloud base, the Met man does that. If you mean how is the cloud base expressed, it depends on the forecast you're reading. A Graphical Area Forecast gives cloud base above sea-level and an aerodrome forecast (TAF) or (TTF), gives cloud base above ground level.