Although clouds look light and fluffy, they contain vast amounts of water and can weigh millions to billions of kilograms, depending on their size and water content, making some individual clouds heavier than many large structures on Earth.
What are clouds made of
Clouds consist of tiny liquid water droplets or ice crystals suspended in air; the visible part is condensed water, and it is this liquid or frozen water that contributes essentially all of a cloud’s mass.
How scientists estimate cloud mass
Researchers estimate cloud weight by measuring the average water content per cubic metre and multiplying by an estimated cloud volume; a typical cumulus cloud roughly one kilometre across can contain on the order of 100 000 to 1 000 000 tonnes of water, depending on droplet density and size.
Why heavy clouds stay aloft
Clouds remain suspended because the tiny droplets are supported by updrafts and because the droplets’ low terminal velocity keeps them from falling quickly; the surrounding air provides buoyant and dynamic support that balances the water’s weight.
Implications and examples
Knowing cloud mass matters for weather forecasting and hydrology because the total water available determines rainfall potential; simple public comparisons—such as a cumulus cloud containing the mass of hundreds of elephants or many hundreds of tons—help convey how much water is aloft during common weather events.
Quick related facts
- Composition: liquid water droplets or ice crystals.
- Typical mass: many clouds weigh millions to billions of kilograms.
- Example: a 1 km3 cumulus cloud can contain on the order of 100 000 to 1 000 000 tonnes of water.
- Support: updrafts and low droplet terminal velocity keep clouds aloft.