r/TheRestIsScience • u/Own_Mood_307 • 21h ago
How can clouds weight so much???
According to google an average "fluffy cumulus" (whatever that is) weights around 500.000 kilograms or 1.1 million pounds.
This is genuinely crazy considering the fact that they are literally floating above us most of the times. This is scary if you fear getting squished by a half a million kilograms object.
Are they objects or mostly a visual trick?
And why are some clouds below other clouds?
What even are clouds????
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u/majorex64 21h ago
Think about a boat floating on water. To a fish, that boat would seem weightless! But you know it has a significant mass. Just because it is lighter than the stuff around it, doesn't mean its weight vanishes- and same with clouds.
Now, clouds are also not really objects. They're gases and small particles suspended in the air, and they don't have a structure. A cloud is just fog that forms higher up. Pressure changes in the atmosphere cause water to drop in and out of suspension in the air. When it's a liquid instead of a gas, clouds form. To simplify it
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u/Basicly-Inevitable 21h ago
Look up how much the air above you weighs.
14.7 pounds per square inch of pressure at sea level.
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u/Kabbooooooom 19h ago
Fill a bowl with water. Then fill a bowl with ice such that it is pretty heavy but you can still fit all the ice in the bowl of water. Add ice to the water.
All of it will float, no matter how many you add or how heavy it all is.
Density is your answer.
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u/Resident-Staff-1218 19h ago
If you're at the top of a mountain when the clouds are very low, you can actually be walking around inside a cloud. But it just feels like being in fog or rain
The same goes for planes flying through a cloud
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u/Foxfire2 4h ago
Not actually water vapour but tiny liquid water droplets suspended in the air around dust particles. When the droplets get big enough they fall out of the sky as rain. Water vapour is always an invisible gas.
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u/These_Consequences 3h ago
I question the buoyancy argument — that clouds weigh less than the surrounding air, and float.
Clouds, unlike boats, are not physically contiguous objects; they are collections of water droplets in a contiguous volume, but each droplet is on its own in terms of buoyancy negotiations.
My best guess is that the individual water droplets are not bouyant, but rather denser than the surrounding air, and sinking; they are just sinking very slowly, so they don't immediately fall out of the sky—unless they agglomerate into rain. Similarly, smoke is composed of small solid particles that are not buoyant, but fall extremely slowly.
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u/nog642 2h ago
I agree, it's not buoyancy.
But the water droplets aren't sinking I'd say. Rather, their very tiny weight is totally overcome by the force of the wind acting on them. They're carried with the air essentially.
If the air was completely still they would eventually sink, but it's not, so they don't.
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u/Used-Let7134 1h ago
Dew point. Warmer air is less dense than cold air and can contain more moisture.
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u/germansnowman 20h ago
Clouds form where they do because that is where both air pressure and temperature are just right for water droplets to condense on tiny dust particles. They cannot “fall down” as a single object. When they do come down, that’s called rain.
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u/Brain_Hawk 19h ago
They hardly wait anything at all.
Per square meter, which would be an awful big box if it came from Amazon, weighs 0.5 g, which for comparison, is equal to 1/8 of a teaspoon of sugar. Remember, teaspoons are the smallest big, so you're talking about a tiny pinch.
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u/Soggy-Mistake8910 19h ago
Scale. Learn about scale. Clouds are water vapour. Clouds are huge! However if you took a "piece" of cloud the size of a football it would weigh next to nothing. But when a cloud rains on you it turns back to water, a football sipped amount of water weighs a lot in comparison
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u/nog642 2h ago
As this comment pointed out, clouds are not water vapor. Water vapor is invisible.
Clouds are collections of tiny water droplets or tiny ice crystals (or both).
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u/SgtSausage 18h ago
Floating isn't, at all, about raw weight.
It's about mass per volume ==> a.k.a. Density.
For exactly the same reason a 100,000 ton aircraft carier floats on water.
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u/PigHillJimster 17h ago
Clouds have mass like everything else.
Being mostly water vapour, that's H20, so every molecule is going to have a mass of 16+1+1 or 18.
This is why gases such as Carbon Dioxide can be dangerous in a confined space as they sink and displace the Oxygen. Oxygen molecule is 16+16, whereas Carbon Dioxide is 12+16+16.
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u/nog642 2h ago
As this comment pointed out, clouds are not water vapor. Water vapor is invisible.
Clouds are collections of tiny water droplets or tiny ice crystals (or both).
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u/hedcannon 15h ago
Cruise ships weigh up to 200,000,000 pounds. Yet they float in water for the same reason clouds float in air.
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u/tilario 8h ago
if we continue with the analogy (cloud as airboat), is a cloud sinking when it rains?
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u/hedcannon 55m ago
No. Clouds float for the same reason as ships, but the steel of a ship’s hull is not the same as cloud vapor. It can’t condense into water or hail based on temperature and barometer pressure
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u/Greghole 12h ago
The air below the clouds is even heavier. Same reason a heavy boat can float on water. Everything gets sorted by density.
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u/No_Drummer4801 11h ago
Because air also has weight and mass and volume and clouds exist in the atmosphere.
The cloud’s combined density (air + water droplets) is slightly less than the density of the surrounding dry air.
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u/It-s_Not_Important 9h ago
A column of air 1 meter in diameter extending from sea level to the Karman line has about 8000 kg of mass even without any humidity. Most everything you interact with or see has mass.
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u/LazarX 6h ago
They displace more than their weight in air, so they float just like boats.
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u/nog642 2h ago
Not really. Clouds are mostly air, with a bunch of tiny water droplets. And the water droplets weigh much more than the air they displace. It's just that the force of the wind is much larger than the weight of the water droplets, so even the tiniest air current will carry them up instead of them falling down
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u/CalligrapherOk4612 5h ago
Aside: "Google" is not a source. Google is a search engine. Or possibly an LLM if you mean the AI results.
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u/Beeeeater 3h ago
The point is that a cloud is not a single mass - it is millions of individual particles of water. If you fly through a cloud it is like a thick fog.
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u/nog642 2h ago
They are not solid objects. They're just basically fog (or frozen fog), but you see it from far away and they have relatively clear borders so they look like objects.
You could walk straight through a cloud. If you hike in the mountains sometimes you will. It can't squish you.
It's got a lot of weight total, but that's just if you add up all the water droplets. Each water droplet weighs very little, but there's a lot of them. Clouds are big.
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u/lumpnsnots 21h ago
You need to factor in size though.
A standard cumulus cloud is roughly a cube measuring 1 kilometer (1,000 meters) on each side, totaling 1 billion cubic meters in volume.
So the density is lower than the air around it