IIUC, Martin 's calculation is the mass of a thermal, and of the water
vapour in it.

Going back to the cloud (air saturated with water vapour and droplets),
to a first approximation, a small summer cu of say 1000 feet deep and
1,000 x 1,000 feet average Xsection would have a mass of around 36,000
tons at STP, I think.

One good for a gold height - say 10,000 feet tall and about that square
in cross section - would be 1,000 times more massive, say 36 million
tons.

The largest UK cu nim I have seen was about 7 miles high, 30 miles long
and say 1 mile deep. Call it equivalent to 5 miles high at STP (allowing
for rarified air at height) that's about 700 million tons mass, if all
air and water vapour. Dunno how to add an allowance for raindrops and
hailstones, but driving under it was like being in a waterfall.

Chris N.






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