Reader Jane write in to notice that clouds look so nice and fluffy and lighter - than - air , so they for sure ca n’t weigh much . Right ?
When Peggy LeMone was in next-to-last heights , a friend ’s pop reflect that same question , and she keep it in the back of her mind for years . Now all maturate up , LeMoneis a researcher at the National Center for Atmospheric Research , and she ’s enter out an solution . Today , she shares her swarm - weighing proficiency with us .
First , envision out how dull the cloud is . scientist have measured the pee density of a typical heap cloud ( the white , downy one you see on a nice twenty-four hours ) as 1/2 gram per cubic meter — about a small marble ’s Charles Frederick Worth of water in a space you and a friend could comfortably sit in . The compactness will be heavy for unlike types of clouds .
Next , count on out how big the swarm is . By measuring a cloud ’s shadow when the sun is direct above it , you could get an estimation of its width . LeMone does this by watching her odometer as she drives under a cloud . A distinctive cumulus , she says , is about a kilometer across , and usually roughly cubical — so a kilometer longsighted and a km tall , too . This fall in you a cloud that ’s one billion cubic meters in intensity .
Do the math with the density and intensity to determine the total weewee content of the cloud . In this case , it ’s 500,000,000 gram of water , or 1.1 million pounds . That ’s a lot of weight to wrap your head around , so LeMone suggests putting it in more conversant condition , like elephants . That cloud weighs about as much as 100 elephants . If you ’re a Democrat and you ’re feeling partisan , she says , you could step in 2500 donkeys . If you care more for dinosaurs than politics , you could also say the swarm weighs about as much as 33 apatosauruses .
If all those elephants or donkeys or dinosaur were hanging out in the sky , they ’d lessen . So how does a several - hundred - ton cloud abide directionless ? For one thing , the weight is n’t concentrated in a hundred elephant - sized particle or even a billion marble - sized ones . It ’s dispense among trillions ofreallytiny water droplet unfold out over a really bragging blank . Some of these droplets are so small that you would need a million of them to make one raindrop , and somberness ’s gist on them is somewhat negligible .
What ’s more , the swarm is less heavy than dry air , so it ’s buoyant . It also helps that all those little droplets get some lift from updraft of warm aviation . Those droplets do n’t float forever , though . When the swarm ’s water density increases and the droplet get bounteous and heavier , the cloud finally does fall , chip by little bit , in the anatomy of rain .
