Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: The Scientist on 31/12/2010 09:51:45
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Can clouds support an average person's mass to prevent them from falling? What do you think? Thanks!
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Can clouds support an average person's mass to prevent them from falling? What do you think? Thanks!
Interesting question - ONCE AGAIN by THE Scientist
What sort of clouds are you referring to? (water droplets? Lead vapour? Uranium gas? Pressurised Chromium gas? An emulsion of methane and mercury droplets?)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.fisicx.com%2Fquickreference%2Fimages%2Fclouds.jpg&hash=db82231fa7186bf2d9f31d9a49c44dc7)
What about this cloud?
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.twolvesblog.com%2Fimages%2Fstories%2Fmushroom-cloud.jpg&hash=d8a79d969ed002490388f1a84240f9fd)
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Yes you can and it is done on a daily basis. You need to be able to catch hold of the cloud and hold it in place using a fabric envelope. It is called a hot air balloon.
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Yes you can and it is done on a daily basis. You need to be able to catch hold of the cloud and hold it in place using a fabric envelope. It is called a hot air balloon.
well done!
what about a Helium or Hydrogen filled balloon?
would that work too
Best Wishes
Foolosophy
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What about a cloud of lead?
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I don't think I'll try walking on any clouds...
I suppose you have 2 questions here.
"What makes a cloud float"
"Can it support additional mass"
I must admit that clouds are somewhat bizarre. And, one wouldn't think that drops of water should be able to hang in the sky like they seem to do.
I think the formation of clouds is based on the "Ideal Gas Law"... This is a Science Forum after all.
pV = nRT (http://en.wikipedia.org/wiki/Ideal_gas_law)
This essentially says that the volume of a gas is independent of the molecular weight, and thus the density of a gas is proportional to the molecular weight.
Keep in mind that Oxygen and Nitrogen form dimers. So, if we look at the molecular weights of Oxygen, Nitrogen, and Water, we get:
O2: 2x16 = 32
N2: 2x14 = 28
H2O:2x1+16 = 18
What you find is that the molecular weight, and thus the density of water vapor is much less than that of Oxygen and Nitrogen (air).
This, along with a relatively high vapor pressure of water would create an elevator effect evaporating water and raising it into the higher atmospheric levels. As the vapor rises, it decreases the humidity at the surface, and more water evaporates.
However, the higher levels of the atmosphere are much cooler.
And, thus the water vapor condenses into water droplets. And one gets clouds. Even with two water molecules joining, and the droplet is heavier than air (Molecular weight 18+18=36).
Atmospheric pressures, and the ability for these droplets to separate and recombine would tend to make the clouds tend to hover in one place. Too big of droplets, and one gets RAIN.
The balance where the cloud is in the sky wouldn't tend to support weight, and there is nothing to stand on.
However,
Next time you wish to go for a balloon trip. Perhaps try a WATER BALLOON!!!
If you don't get off the ground quickly, perhaps heat it to 101°C.
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Can clouds support an average person's mass to prevent them from falling? What do you think? Thanks!
Interesting question - ONCE AGAIN by THE Scientist
What sort of clouds are you referring to? (water droplets? Lead vapour? Uranium gas? Pressurised Chromium gas? An emulsion of methane and mercury droplets?)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.fisicx.com%2Fquickreference%2Fimages%2Fclouds.jpg&hash=db82231fa7186bf2d9f31d9a49c44dc7)
What about this cloud?
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.twolvesblog.com%2Fimages%2Fstories%2Fmushroom-cloud.jpg&hash=d8a79d969ed002490388f1a84240f9fd)
Those two pictures are interesting. Thanks Foolosophy.
Well, I'd say a cloud in general. Those everyday clouds you see when the sky is bright and when there is no rain. I can't put it better myself, can you help? Thanks again!
Best Wishes and Happy New Year!
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....not sure if I can help you in any way
What do you think?
Yours Sincerely
Foolosophy
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The air cools and the water condenses out but the act of condensing releases a great deal of heat which also tends to reinforce the updraft. This is what creates the intense updraft in thunderheads.
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What makes clouds float?
I would have liked to answer "Small pink teddy bears throwing fairy-dust" but as I know that that isn't the correct scientific terminology I will refrain from it. But if we name those creatures 'density'?
'Density' makes them float :)
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What makes clouds float?
'Density' makes them float :)
"Density" is not the reason that clouds float
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The air cools and the water condenses out but the act of condensing releases a great deal of heat which also tends to reinforce the updraft. This is what creates the intense updraft in thunderheads.
Good point.
So the density of water vapor makes it float. And, the act of condensing would also create an updraft to hold them up there.
And... that would also explain how some areas can generate hailstones the size of a tennis ball.
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The air cools and the water condenses out but the act of condensing releases a great deal of heat which also tends to reinforce the updraft. This is what creates the intense updraft in thunderheads.
So the density of water vapor makes it float.
Density is not the reason that clouds float
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Density and buoyancy goes hand in hand.
But it depends on how you look at it.
So how do you look at it :)
"Condensation or deposition of water above the Earth's surface creates clouds. In general, clouds develop in any air mass that becomes saturated (relative humidity becomes 100%). Saturation can occur by way of atmospheric mechanisms that cause the temperature of an air mass to be cooled to its dew point or frost point."
There are several nice links in the post too.
how air temperature, pressure, and density are related to cloud formation. (http://answers.yahoo.com/question/index?qid=20070612054831AAeu1mj)
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Apropos nothing, I think QC mentioned Gaia, or at least an equivalence, in an earlier thread discussing Earth. Now, that may seem as 'mumbo jumbo' but I found it quite fascinating. Take a look here The Gaia Hypothesis. (http://www.physicalgeography.net/fundamentals/5d.html)
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Apropos nothing, I think QC mentioned Gaia, or at least an equivalence, in an earlier thread discussing Earth. Now, that may seem as 'mumbo jumbo' but I found it quite fascinating. Take a look here The Gaia Hypothesis. (http://www.physicalgeography.net/fundamentals/5d.html)
I must protest. I was likening an understanding of biological processes to Mother nature, but I did state that I did not believe that Mother Nature truely was a decision making automaton like human beings are. I only said that sometimes it is difficult not run into language and personify nature as it reflects directly our natural beings.
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Density and buoyancy goes hand in hand.
But it depends on how you look at it.
So how do you look at it :)
"Condensation or deposition of water above the Earth's surface creates clouds. In general, clouds develop in any air mass that becomes saturated (relative humidity becomes 100%). Saturation can occur by way of atmospheric mechanisms that cause the temperature of an air mass to be cooled to its dew point or frost point."
There are several nice links in the post too.
how air temperature, pressure, and density are related to cloud formation. (http://answers.yahoo.com/question/index?qid=20070612054831AAeu1mj)
Density is not the reason that clouds float.
How can very fine particles remain suspended in air when they are clearly more dense than the air itself?
What is causing them to avoid settling out towards the ground?
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I agree with Foolosophy. I don't see how density can be the cause, as ice and water droplets are more dense than air.
The cause is that these droplets are tiny enough that updrafts in the atmosphere can hold them aloft.
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I agree with Foolosophy. I don't see how density can be the cause, as ice and water droplets are more dense than air.
The cause is that these droplets are tiny enough that updrafts in the atmosphere can hold them aloft.
thats a plausible explanation.
its like the fine dust particles that float around in the air.
Smoke particles have densities that are orders of magnitude greater than the surroudning air - but they are very fine. Why does a smoke plume behave the way it does?
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I agree with Foolosophy. I don't see how density can be the cause, as ice and water droplets are more dense than air.
The cause is that these droplets are tiny enough that updrafts in the atmosphere can hold them aloft.
I don't know the science behind clouds, but surely this explanation JP cannot sustain on its own. You'd be surprised how much water is really in the atmosphere waiting to condense...
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what !!
Maybe :)
Keep on and I may, just may, change my mind..
But I want you to understand that our "Small pink teddy bears throwing fairy-dust" will have to go with that too. Are you really prepared to do that?
It's a cruel cruel world.
"Don't cry children, I'm sure the big meanies will change their mind now."
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I think the airmass that forms a cloud is quite dynamic, and this produces a mechanism that keeps the minute water particles aloft.
You may have noticed how the ride in an aeroplane suddenly gets rather bumpy as soon as it enters a cloud. I would think this is an indication how much turbulence there can be in clouds. However, that only just occurred to me, so I would not be very surprised to learn that it's wrong.
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I've had some time to study the science behind clouds. Clouds are as I suspected a gas phase, which as most of us will all know from elementary science is one of four well-known phases of matter. The gas phase is simply a water vapour, so it should be of no surprise clouds stay afloat. Eventually, this water vapour will condense - it is not condensed in the air, and is not kept afloat by any special mechanism, like which was mentioned perhaps ''droplets are tiny enough that updrafts in the atmosphere can hold them aloft'' - Droplets are not in this form in the sky - droplets occur when the gas phase changes into a liquid phase, and hence, which is why clouds condense into rain.
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Here's a little info courtesy of wiki ~ water vapour is in fact lighter than air. So air cannot keep water vapour afloat.
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Density of water vapor (from my calculations above) is lighter than air, and is what gets single-molecule water vapor up into the air at the level of the clouds. A very fine aerosol, while greater density than air, will tend to float in the air for some time, but slowly settles down.
(Quantum, remember, if density is lower than air, like hydrogen or helium, it will tend to rise, if it is heavier than air, like propane, it will tend to sink).
Condensation would tend to release heat (Soul Surfer) which would cause convection and updrafts.
Condensation would also tend to cause a decrease in volume, and thus a decrease in pressure, and create more turbulence.
While we see clouds that leisurely float across the sky, my guess is that it is a much more dynamic process.
For example, if clouds tend to form at 1000 feet due to high vapor density, and low temperatures, then as mentioned, that might tend to create some updrafts. However, if the droplets fall down to 900 feet, the air temperature may be higher and the vapor density may be lower, and the falling droplets would evaporate back into vapor, which would cause a localized high pressure, and the now lighter than air vapor would tend to rise again up into the cloud, only to re-condense.
As mentioned previously, not all clouds are created equally. Thunderheads are likely much different from ordinary high floating clouds. While not a meteorologist, I'm thinking that a thunderhead would be formed with very cold air combining with very humid air, with a more extreme gradient than normally experienced.
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The gas phase is simply a water vapour, so it should be of no surprise clouds stay afloat.
I don't think so QC. Water vapour in the gas phase is invisible.
The reason clouds are visible is because some of the water vapour condenses around minute hygroscopic particles.
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Water vapour is a gas phase... I am confused. I am informed that ''Water vapor is a potent greenhouse gas along with other gases such as carbon.'' Water vapour you say in its gas phase cannot be seen - supposing this is true, then how can water vapour be seen when boiling water?
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But still yeh, I am confused about you treating water vapour as being conditional when talking about a gas phase... can you expand on this?
Thanks
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then how can water vapour be seen when boiling water?
Ah, right. Steam (which is the gas phase of water) is actually invisible. When you see stuff coming out of a boiling kettle, what you are seeing is water particles that condensed out of the steam when they lost their heat to the ambient air outside the kettle.
Superheated steam escaping from a boiler can be very dangerous because it can be invisible for quite a distance away from the boiler. Consequently, it can cause severe burns before the victim even realizes what's happening.
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Take a look at this one. The writing is all together, in one big chunk of words, but you can always start with searching on ' buoyancy ' Clouds, Stability, and Buoyancy (http://teachingcompany.12.forumer.com/a/9-clouds-stability-and-buoyancy-part-1_post2598.html) Be prepared though, really reading it you will learn more than you ever wanted to know about clouds :)
And if you still don't see what I mean?
"Don't you cry now.. The pixies will make it right children. The teddybears will come back."
Ah, where were I?
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then how can water vapour be seen when boiling water?
Ah, right. Steam (which is the gas phase of water) is actually invisible. When you see stuff coming out of a boiling kettle, what you are seeing is water particles that condensed out of the steam when they lost their heat to the ambient air outside the kettle.
Superheated steam escaping from a boiler can be very dangerous because it can be invisible for quite a distance away from the boiler. Consequently, it can cause severe burns before the victim even realizes what's happening.
I'll just need to take your word for it ~ I know really nothing scientific about the subject, only what I read recently.
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then how can water vapour be seen when boiling water?
Ah, right. Steam (which is the gas phase of water) is actually invisible. When you see stuff coming out of a boiling kettle, what you are seeing is water particles that condensed out of the steam when they lost their heat to the ambient air outside the kettle.
Superheated steam escaping from a boiler can be very dangerous because it can be invisible for quite a distance away from the boiler. Consequently, it can cause severe burns before the victim even realizes what's happening.
I'll just need to take your word for it ~ I know really nothing scientific about the subject, only what I read recently.
No need to take my word for it. From "Steam" on Wiki (although not necessarily the most reliable source)
"In common speech, steam most often refers to the visible white mist that condenses above boiling water as the hot vapor mixes with the cooler air. This mist consists of tiny droplets of liquid water. Pure steam emerges at the base of the spout of a steaming kettle where there is no visible vapor."
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The gas phase is simply a water vapour, so it should be of no surprise clouds stay afloat.
I don't think so QC. Water vapour in the gas phase is invisible.
The reason clouds are visible is because some of the water vapour condenses around minute hygroscopic particles.
This is correct.
Water vapour itself (ie steam) is not visible to the naked eye.
Notice the breath from your mouth when you exhale on a cold morning?
And we all know Why this doesnt occur each and every time we exhale?
(and of course density is NOT the reason clouds float. Smoke particles float away in plumes and yet the denisty of a smoke particle can be several thousand times greater than that of the surrounding air. So why dont the smoke particles settle out rapidly? Seek and thy shalt discover my child)
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heh :)
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What is 'pressure'?
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heh :)
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What is 'pressure'?
Only The Scientist can answer that sublime question
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(and of course density is NOT the reason clouds float. Smoke particles float away in plumes and yet the denisty of a smoke particle can be several thousand times greater than that of the surrounding air. So why dont the smoke particles settle out rapidly? Seek and thy shalt discover my child)
"So, so, so, he was only joking children."
"Yes, it's the fairy dust."
"N000, stop that, he did not mean that you should go out the window again Peter. We're on the tenth floor, remember?"
"YES! for the ninthyeleventh time. Tinkle bell will be here as soon as she can, Someone has to work."
Foolosophy, now you've upset the kids.
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(and of course density is NOT the reason clouds float. Smoke particles float away in plumes and yet the denisty of a smoke particle can be several thousand times greater than that of the surrounding air. So why dont the smoke particles settle out rapidly? Seek and thy shalt discover my child)
"So, so, so, he was only joking children."
"Yes, it's the fairy dust."
"N000, stop that, he did not mean that you should go out the window again Peter. We're on the tenth floor, remember?"
"YES! for the ninthyeleventh time. Tinkle bell will be here as soon as she can, Someone has to work."
Foolosophy, now you've upset the kids.
Careful Yoron, you may be ejected from this establishment for posting potentially humourous comments that have no scientific conservatism attached to them