Next time you’re stuck for a conversational opener, try this fascinating factoid.

Q: How much does a cloud weigh?

A: The average cumulus cloud weighs 1.1 million pounds. Wow!

They look so soft and fluffy up there. But we all know both air and water have weight, so they must weigh SOMETHING, right?

If clouds are made up of particles, then they must have weight and density (the weight for a chosen volume, such as a cubic inch or meter).

To calculate weight, scientists evaluate the weight of the water droplets in the cloud, plus the weight of the air (mostly above the cloud, pressing down). One estimate of cumulus cloud density is given at https://www.sciencealert.com/this-is-how-much-a-cloud-weighs, as a density of about 0.5 gram per cubic meter. A 1-cubic kilometer (km3) cloud contains 1 billion cubic meters.

Doing the math: 1,000,000,000 x 0.5 = 500,000,000 grams of water droplets in our cloud. That is about 500,000 kilograms or 1.1 million pounds (about 551 tons), or roughly 100 elephants. But, just as oil floats on water because it’s less dense, that “heavy” cloud is floating over your head because the air below it is even heavier— the lesser density of the cloud allows it to float on the dryer and more-dense air.