An average cumulus cloud weighs about 500 tonnes.
Why it is true
A typical cumulus cloud contains about 500 tonnes of water in the form of droplets. The weight does not fall on us because the droplets are very small and rising warm air keeps them suspended. When droplets join and become larger, they fall as rain.
Source: NOAA
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.
Related facts
Morning Glory clouds form in Australia and can be up to a thousand kilometres long.
The aurora borealis is a purely visual phenomenon and does not emit any sound.
The total weight of all insects on Earth is estimated to be roughly seventeen times that of all humans.
Lightning strikes the Earth about 100 times per second.
