X: Mythbust Monday — How Much Does a Cloud Weigh?

Pretty much nothing, right? Aren’t they composed entirely out of water vapor and the giggles of children?

Wrong. Clouds are so heavy that the National Center for Atmospheric Research in Boulder, Colorado measures cloud weight in elephants, while the National Oceanic and Atmospheric Association prefers blue whales.

If you’re getting measured in elephants and blue whales, you know you’re pretty heavy.

But how does one go about measuring the weight of a cloud? As the nuns in The Sound of Music wondered, “How do you catch a cloud and pin it down?”

You don’t. You have to figure it out with math. Normally the prospect of using math makes me want to run away to join a weird, new-agey, tree hugger community, but when it’s for the purpose of weighing a cloud, I shall suffer through.

The things I do for you.

Anyway, the weight of a cloud is found by multiplying density times volume. The density of a cloud is 1.003 kg/m³, and the average cumulus cloud contains about 1,000,000 cubic meters of water vapor. I’m sure they figured out the volume of a cloud very scientifically.

“Hey Carl, how many cubic meters of water vapor are in that cloud?”

“Well I’d say about a million, Dave. Yep, just about a million.”

Very scientific, I’m sure.

Either way, that puts the average cumulus cloud at 1.003 billion kilograms, which is the same as 2.2 billion pounds, 6,268.75 blue whales, or 200,000 elephants. A little baby cloud weighs just 100 elephants. That’s about 2,500 donkeys, for those of you who are concerned about the non-partisan nature of this blog. And for those of you who get nervous around politics, it’s the same as 33 apatosauruses.

Luckily, weight isn’t the same as mass, so you can still go outside without worrying about being squashed by 33 – 66,000 apatosauruses (apatosauri?) worth of water vapor.

So next time you’re watching clouds, you can think, “That one looks like a cat! That one looks like 6,268.75 blue whales vaporized and spread out over a billion cubic meters of atmosphere!”

Or maybe not.


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