# How many raindrops does one cloud contain?
**URL:** https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025
**Category:** Factual Questions
**Created:** [September 24, 2008, 5:48pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025 "2008-09-24T17:48:55Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@Grapefruit](https://boards.straightdope.com/u/Grapefruit)
#### Post date: [September 24, 2008, 5:48pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/1 "2008-09-24T17:48:55Z")
I’m watching the rain clouds loom overhead and it has me wondering. Is it possible to put a range of numbers onto a cloud? I know there are different sizes, but let’s consider this an average sized cloud that holds the maximum capacity of water before it bursts and sends showers down to the earth.
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### Author:  [@Napier](https://boards.straightdope.com/u/Napier)
#### Post date: [September 24, 2008, 6:22pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/2 "2008-09-24T18:22:43Z")
Good question.
So, depending on the temperature, air in a nice warm cloud could certainly include more than a percent by mass of water. Air weighs a kilogram per cubic meter, and one percent of that is 10 grams per cubic meter. If a cloud is as big as a kilometer cube, or a billion cubic meters, that would be ten billion grams of water, or ten million liters of water. If the raindrops are the volume of a 3 mm cube, or 30 mm^3, there are 0.03 of them in a cubic millimeter, or 30 in a cubic centimeter, or 30,000 of them in a cubic decimeter or a liter. So that’s 3E10 drops in the cloud.
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### Author:  [@Outpits](https://boards.straightdope.com/u/Outpits)
#### Post date: [September 24, 2008, 7:30pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/3 "2008-09-24T19:30:40Z")
Of course, the pedantic answer is that there are no raindrops in a cloud, merely droplets. Once enough droplets have combined to form a raindrop, it falls out of the cloud. So, maybe there are a few transition state drops, but not many. Your question really is one more of how many potential raindrops are in a cloud?
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### Author:  [@CC](https://boards.straightdope.com/u/CC)
#### Post date: [September 24, 2008, 7:38pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/4 "2008-09-24T19:38:54Z")
> [@Napier](#):
>
> …Air weighs a kilogram per cubic meter…
Can we start these calculations over? 2.2 lbs per cubic meter? Air? Nope.
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### Author:  [@Squink](https://boards.straightdope.com/u/Squink)
#### Post date: [September 24, 2008, 7:39pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/5 "2008-09-24T19:39:33Z")
> [@Napier](#):
>
> or ten million liters of water.
By way of comparison, an Olympic pool (25 X 50 X 2 meters) contains two point five million liters of water.
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### Author:  [@Grapefruit](https://boards.straightdope.com/u/Grapefruit)
#### Post date: [September 24, 2008, 7:46pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/6 "2008-09-24T19:46:21Z")
Interesting calculations so far… I’m not too big of a math person so I have to mull it over a bit. Does it matter what the air is comprised of? I mean, I know - oxygen… but what if I were in a nitrogen or CO2 heavy atmosphere? Would that affect the chemistry of rain clouds (ie acid rain heavier than normal rain?) and thus the number of droplets a cloud contains before release?
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### Author:  [@Morgenstern](https://boards.straightdope.com/u/Morgenstern)
#### Post date: [September 24, 2008, 7:47pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/7 "2008-09-24T19:47:02Z")
Some clouds contain ice, not liquid water. Wouldn’t that make a difference in volume?
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### Author:  [@muldoonthief](https://boards.straightdope.com/u/muldoonthief)
#### Post date: [September 24, 2008, 7:52pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/8 "2008-09-24T19:52:47Z")
> [@CC](#):
>
> Can we start these calculations over? 2.2 lbs per cubic meter? Air? Nope.
[Yup.](http://en.wikipedia.org/wiki/Air_density)
The density of air, ρ (Greek: rho) (air density), is the mass per unit volume of Earth’s atmosphere, and is a useful value in aeronautics. Air density decreases with increasing altitude, as does air pressure. At sea level and at 20 °C, air has a density of approximately 1.2 kg/m3."
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### Author:  [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)
#### Post date: [September 24, 2008, 8:09pm UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/9 "2008-09-24T20:09:37Z")
> [@CC](#):
>
> Can we start these calculations over? 2.2 lbs per cubic meter? Air? Nope.
**muldoonthief** already got to it, but the misconception here is probably that a one meter cube balloon doesn’t weigh any more than the same deflated balloon. This is because the pressures are the same on the inside and outside (otherwise, the balloon would equilibriate to a different size), making the force of gravity canceled out by the buoyant effect of the air under the balloon. 1 kg per m[sup]3[/sup] is a commonly accepted estimation for back of the envelope calculations (it’s the density I used when calculating the drag due to air resistance in the [paddle with holes](http://boards.straightdope.com/sdmb/showpost.php?p=10226510&postcount=25) thread.)
> [@Outpits](#):
>
> Of course, the pedantic answer is that there are no raindrops in a cloud, merely droplets. Once enough droplets have combined to form a raindrop, it falls out of the cloud. So, maybe there are a few transition state drops, but not many. Your question really is one more of how many potential raindrops are in a cloud?
If we’re going to be pedantic, we would say that not all raindrops start falling from the very bottom of the cloud. Ones that start falling from near the top would certainly be defined as being _in_ the cloud at a snapshot in time. 😛
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### Author:  [@Xema](https://boards.straightdope.com/u/Xema)
#### Post date: [September 25, 2008, 12:08am UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/10 "2008-09-25T00:08:09Z")
> [@Santo\_Rugger](#):
>
> …the pressures are the same on the inside and outside
Could we go with “nearly the same” ? Otherwise, the air wouldn’t rush out of the balloon when you let go of the neck.
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### Author:  [@Xema](https://boards.straightdope.com/u/Xema)
#### Post date: [September 25, 2008, 12:17am UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/11 "2008-09-25T00:17:12Z")
> [@CC](#):
>
> 2.2 lbs per cubic meter? Air? Nope.
If we’re talking about sea level and 20 degrees C, you are quite right to question this figure - the correct value is 2.6 lbs per cubic meter.
(IOW, air has a higher density than many people assume.)
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### Author:  [@Cider\_Depot](https://boards.straightdope.com/u/Cider_Depot)
#### Post date: [September 25, 2008, 12:45am UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/12 "2008-09-25T00:45:18Z")
> [@Grapefruit](#):
>
> Interesting calculations so far… I’m not too big of a math person so I have to mull it over a bit. Does it matter what the air is comprised of? I mean, I know - oxygen… but what if I were in a nitrogen or CO2 heavy atmosphere? Would that affect the chemistry of rain clouds (ie acid rain heavier than normal rain?) and thus the number of droplets a cloud contains before release?
You are in a nitrogen heavy atmosphere.
- 78% nitrogen
- 20% oxygen
- 2% and the rest
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### Author:  [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)
#### Post date: [September 25, 2008, 5:32am UTC](https://boards.straightdope.com/t/how-many-raindrops-does-one-cloud-contain/465025/13 "2008-09-25T05:32:15Z")
> [@Xema](#):
>
> Could we go with “nearly the same” ? Otherwise, the air wouldn’t rush out of the balloon when you let go of the neck.
Good point. I glossed over the force the elastic was exerting. “Nearly the same” it is.