If clouds are made of water, why don’t they fall out of the sky?
The water droplets in clouds are very tiny – perhaps one tenth of a millimetre across and weighing little more than a dust particle.
Objects this small don’t have as strong a gravitational pull as bigger things, such as raindrops, which rapidly fall from the sky.
The tiny droplets of water get caught in updraughts, or convection currents, and are swept higher into the atmosphere where they gather together to make a cloud.
They are so light that the updraughts keep them up in the sky – it’s only when clouds get squashed together and the tiny droplets bump into one another and join together that they make big droplets and fall from the sky as rain. Clouds are just like fog, but higher in the air.