How much does a cloud weigh?

  • 11.12.2022
  • Live Science

So just how much does a cloud weigh? And how do you weigh a cloud? We asked the experts to find out.

Clouds are composed mainly of air and millions of tiny water droplets, which form when water condenses around a "seed" particle. Seed particles can be anything from nitric acid to vapors released by trees, but they are generally very tiny.

Several years ago, Margaret LeMone(opens in new tab), an atmospheric scientist at the National Center for Atmospheric Research in Boulder, Colorado, wondered about the weight of the water in an average cumulus cloud. So she did the math. First, she measured the size of a cloud's shadow and estimated its height, assuming a roughly cubic shape. Clouds are not typically cube shaped, but cumulus clouds are frequently about as tall as they are wide, so this assumption helped streamline the volume calculation. Then, based on prior research, she estimated the density of water droplets at around 1/2 gram per cubic meter. "I came up with around 550 tons [499 metric tons] of water," LeMone said.

That's approximately the weight of 100 elephants suspended above your head. "It's really impressive," Soroohsian said.

Of course, different types of clouds have different weights. For example, "cirrus clouds are much lighter, because they have far less water per unit volume," LeMone told Live Science. And cumulonimbus clouds (the dark thunderheads you see just before a storm) tend to be much heavier.

However, "the entire volume of the cloud is not just the droplets; there's air, too," Sorooshian said. If someone wanted to take LeMone's calculations a step further, they could factor in the weight of the air between each droplet.