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Post by duwayne on Oct 8, 2018 17:50:19 GMT
Icefisher, I understand what you are saying. You believe that if someone filled a tank with air and left it sit undisturbed, the gas components would separate (stratify) based on their molecular weights. I’d suggest you check whatever source you trust to see whether there is any significant variation in the ratio of oxygen to nitrogen throughout the atmosphere (troposphere). The fact that the ratio doesn’t change with altitude is not because of wind. Wind is not that perfect. There is a good scientific reason that gases stay mixed. Science says they don't stratify. I can understand why someone might believe that “lighter gases” float upwards in the atmosphere. After all there are lighter than air blimps which stay in the air. The difference is that the helium gas is separated and trapped within the blimp. If the gas were to be released it would succumb to the forces which cause it to redistribute evenly at all levels throughout the atmosphere even if the wind weren’t blowing and even though it is low molecular weight. You understand wrong I never said any such thing or anything close to that. The discussion is about the atmosphere which is completely different with compression operating from gravity alone rather than some pumped up uniform pressure throughout the system as you probably deal with in your job if you are doing a lot of phase change work in an industrial setting. Further since the atmosphere does in fact have stratification this argument should be done. I don't have a lot of interest in figuring out exactly what prevents or enables stratification in gases, but can admit to the possibility that its relevant to discussion of the atmosphere and perhaps even climate change. But what is clear is our atmosphere does not act as a uniformly compressed tank of air mostly likely because its not. Of more interest is diffusion of heat in the atmosphere by whatever means it occurs. Water vapor does rise and it may even not be primarily because it is a lighter molecule it could be because of being able to absorb both solar heat and IR surface heat which potentially makes it lighter due to expansion. Further, trying to get back to the relevant point of condensation what applies between gases does not apply between a gas and a liquid which is the topic as I understood it of this thread. If you have something to contribute to that I would certainly appreciate it as I am most definitely in an information gathering mode on that specific topic and only interjected myself into this conversation on that point alone. An interjection that was based as I said on observations of water vapor IR sensor measurements appearing colder than water IR sensor measurements. If I am correct on that point (which only appears to me to be the case and certainly could be mistaken), then I see two possible explanations. 1) the water is as high as the water vapor and thus giving off additional IR that influences the measurement and is detected when a water vapor channel is compared to a water channel. or 2) the water is lower in the atmosphere and thus warmer but can't be seen on the water vapor channel and can only be seen on the water channel. Thus if 2 is the case its not proof a latent heat IR release, for 1 is the case then it is. But neither case disproves a latent heat IR release. Then taking a page from climate science I can conclude that is more likely that latent heat IR release occurs. . . .but I am not going to claim that settles the science on the matter. On the matter of stratifying gases in a compressed tank, that never once occurred to me. If it had back in the days I did a lot of scuba diving that would have been a huge concern, but quite frankly I never even thought about it and simply just followed my scuba instructors definition to put the mask on securely and give great consideration to how long I stayed down, don't hold my breath when coming up, and pay attention to proper decompression practices if I dove below a certain level so as to avoid nitrogen stratifying in bubbles in my bloodstream. Icefisher, no, you didn’t mention a tank. So let the example be the bottle you used for the refrigerator latent heat “experiment” and fill it with air, cap it and let it sit for an extended period. Will the oxygen settle to the bottom of the bottle. Or use the example of a house that has been shut up without any air circulation for a few weeks. Do the oxygen and nitrogen stratify? If it’s a low ceiling single story will I pass out from breathing the nitrogen when I walk into the room? Or the more direct question, do oxygen and nitrogen stratify in containers or in the atmosphere?
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Post by nautonnier on Oct 8, 2018 20:58:42 GMT
Anyone who has flown a lot knows that the atmosphere is stratified. This is not a gas experiment in a laboratory. Cirrostratus, Nimbostratus, tropopause, stratopause, inversion layer, etc etc. Climb out and see a haze layer then a set of cumulus clouds that start at a precise altitude then the zero degree isotherm etc etc, Nautonnier, I hate to ask this but do you know the difference between a gas and a liquid and a solid? Do you know that clouds are suspended liquids and/or solids. Please give a direct answer on this and not a runaround. The atmosphere is stratified get over it. Watch an aircraft climb into a humid layer of air and start contrailing. Lenticular clouds form as waves in layers of air due to orographic uplift go up above the condensation point of the lapse rate and back down again. Or perhaps you don't agree that there is a tropopause, stratopause and mesopause? There are visible layers in the atmosphere whether you want to agree with it or not. and cumulus starting at a fixed point at the top of the haze layer and all reaching the same level - or layer persistent contrails in a layer of humid air - non-persistent contrails above them in a layer of less humid air...
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Post by icefisher on Oct 8, 2018 21:37:36 GMT
You understand wrong I never said any such thing or anything close to that. The discussion is about the atmosphere which is completely different with compression operating from gravity alone rather than some pumped up uniform pressure throughout the system as you probably deal with in your job if you are doing a lot of phase change work in an industrial setting. Further since the atmosphere does in fact have stratification this argument should be done. I don't have a lot of interest in figuring out exactly what prevents or enables stratification in gases, but can admit to the possibility that its relevant to discussion of the atmosphere and perhaps even climate change. But what is clear is our atmosphere does not act as a uniformly compressed tank of air mostly likely because its not. Of more interest is diffusion of heat in the atmosphere by whatever means it occurs. Water vapor does rise and it may even not be primarily because it is a lighter molecule it could be because of being able to absorb both solar heat and IR surface heat which potentially makes it lighter due to expansion. Further, trying to get back to the relevant point of condensation what applies between gases does not apply between a gas and a liquid which is the topic as I understood it of this thread. If you have something to contribute to that I would certainly appreciate it as I am most definitely in an information gathering mode on that specific topic and only interjected myself into this conversation on that point alone. An interjection that was based as I said on observations of water vapor IR sensor measurements appearing colder than water IR sensor measurements. If I am correct on that point (which only appears to me to be the case and certainly could be mistaken), then I see two possible explanations. 1) the water is as high as the water vapor and thus giving off additional IR that influences the measurement and is detected when a water vapor channel is compared to a water channel. or 2) the water is lower in the atmosphere and thus warmer but can't be seen on the water vapor channel and can only be seen on the water channel. Thus if 2 is the case its not proof a latent heat IR release, for 1 is the case then it is. But neither case disproves a latent heat IR release. Then taking a page from climate science I can conclude that is more likely that latent heat IR release occurs. . . .but I am not going to claim that settles the science on the matter. On the matter of stratifying gases in a compressed tank, that never once occurred to me. If it had back in the days I did a lot of scuba diving that would have been a huge concern, but quite frankly I never even thought about it and simply just followed my scuba instructors definition to put the mask on securely and give great consideration to how long I stayed down, don't hold my breath when coming up, and pay attention to proper decompression practices if I dove below a certain level so as to avoid nitrogen stratifying in bubbles in my bloodstream. Icefisher, no, you didn’t mention a tank. So let the example be the bottle you used for the refrigerator latent heat “experiment” and fill it with air, cap it and let it sit for an extended period. Will the oxygen settle to the bottom of the bottle. Or use the example of a house that has been shut up without any air circulation for a few weeks. Do the oxygen and nitrogen stratify? If it’s a low ceiling single story will I pass out from breathing the nitrogen when I walk into the room? Or the more direct question, do oxygen and nitrogen stratify in containers or in the atmosphere? Duwayne this discussion started when I said: "Water vapor is lighter than air and water is heavier than air. Water vapor rises and water falls in the air, in general." And the post I made immediately before that I said: "And the water vapor would not be strongly convecting unless it was hotter than the surrounding air" As water vapor convects huge amounts of heat are being loaded into the atmosphere warming every layer the water vapor convects through. Eventually this heat will be lost to space from the atmosphere. The image you see on the satellite is less radiation than before the convection but thats because the signal you are looking at is at a higher elevation. The entire air column has been heated and all that heat is much cooler than the surface you were viewing beforehand. You, as Nautonnier likes to say, are witnessing heat on the way to space. The average residence time for water vapor in the atmosphere is 9 days so after this convection for the next 9 days the atmosphere will be emitting to space a lot more radiation than the atmosphere would if the water on the surface had never evaporated. Nautonnier is actually bring the conversation back around to its original discussion and because for some strange reason you want to focus on molecular rates, diffusion, air tanks or bottles and rooms and who knows what else. You need to explain why you think what gases do in a bottle is at all relevant to the discussion. I am not seeing any relevance so you need to educate me. Instead it seems you are telling Nautonnier that he is doing a runaround when all he appears to be doing is trying to keep it on the original track.
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Post by duwayne on Oct 9, 2018 1:42:51 GMT
Icefisher, I agree that this exchange started with your statement. "Water vapor is lighter than air and water is heavier than air. Water vapor rises and water falls in the air, in general."
I am trying to make sure I understand what you are saying. Are you saying that because water vapor has a lower molecular weight than oxygen and nitrogen, it will rise within the atmosphere (troposphere) and because of its lower molecular weight, it will ultimately “float”, or whatever word you would like to use to describe the movement, to the top above the oxygen and nitrogen unless interfered with by the wind?
If you want to use different words, do so, but I am trying to find out if you mean that individual gases will stratify based on molecular weight.
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Post by duwayne on Oct 9, 2018 1:57:08 GMT
Nautonnier, I hate to ask this but do you know the difference between a gas and a liquid and a solid? Do you know that clouds are suspended liquids and/or solids. Please give a direct answer on this and not a runaround. The atmosphere is stratified get over it. Watch an aircraft climb into a humid layer of air and start contrailing. Lenticular clouds form as waves in layers of air due to orographic uplift go up above the condensation point of the lapse rate and back down again. Or perhaps you don't agree that there is a tropopause, stratopause and mesopause? There are visible layers in the atmosphere whether you want to agree with it or not. and cumulus starting at a fixed point at the top of the haze layer and all reaching the same level - or layer persistent contrails in a layer of humid air - non-persistent contrails above them in a layer of less humid air... Those are nice pictures of suspended solids and liquids against a background of mixed gases. But what is the relevance to the discussions on whether gases stratify.
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Post by sigurdur on Oct 9, 2018 2:37:19 GMT
If the atmosphere stratified, we would all be dead with our current molecular biology.
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Post by sigurdur on Oct 9, 2018 2:44:54 GMT
Ok. Think of it like this. Different atomic weights mean NOTHING. Because earth is constantly in energy flux, gases move. In a still room, watch the smoke from a candle.
In a total vacuum, gases could potentially stratify, however there is NO gas in a perfect vacuum.
In a temperature inversion, (which once again is joule energy related) you can have suspension of "particles".
Don't confuse particles with a gas. The two are 2 totally different substances.
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Post by icefisher on Oct 9, 2018 4:04:23 GMT
Icefisher, I agree that this exchange started with your statement. "Water vapor is lighter than air and water is heavier than air. Water vapor rises and water falls in the air, in general." I am trying to make sure I understand what you are saying. Are you saying that because water vapor has a lower molecular weight than oxygen and nitrogen, it will rise within the atmosphere (troposphere) and because of its lower molecular weight, it will ultimately “float”, or whatever word you would like to use to describe the movement, to the top above the oxygen and nitrogen unless interfered with by the wind? If you want to use different words, do so, but I am trying to find out if you mean that individual gases will stratify based on molecular weight. good suggestion! Water vapor rises because its less dense than the surrounding air and water falls because its denser than the surrounding air? Does that make it more understandable for you?
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Post by nonentropic on Oct 9, 2018 5:42:58 GMT
I think there is an issue here.
If air is higher in humidity its lighter it rises relative to dryer air all other things being equal. But remember it will mix in time and being H2O that is dissolved in the air it will potentially condense if temperature falls to the point that the dew point is reached.
The rest and I have not read it all, is in my humble opinion people talking past each other.
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Post by nautonnier on Oct 9, 2018 9:58:27 GMT
If the atmosphere stratified, we would all be dead with our current molecular biology. You are confusing stratified with permanently stratified. On a particular day there are layers for whatever reason - these are visible. The troposphere is a layer of convecting air at the top of this layer convective mixing stops - it is called the tropopause and above it the stratosphere. Even the tropopause is like the surface of any fluid and gets disturbed by waves which can break mixing stratospheric air with tropospheric air. The inversion _layer_ builds as the air cools but is destroyed by convection when the sun warms the surface. Convective currents start for the smallest difference and bubble up just like a lava lamp but invisible. Watch cold water steaming as water evaporates and condenses into the air the steam (small water droplets) _rising_ from the cold surface in the updraft from a lake surface. Fly along between layers of cirro stratus that extend for hundreds of miles. Or sit on a coast in persistent drizzle for days under nimbo stratus rolling in off the sea. Even the sea can be considered stratified with the thermocline marking a temperature layer - that doesn't mean it is impossible for water to move between the layers above and below but it does significantly inhibit such transfers.
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Post by Ratty on Oct 9, 2018 12:34:38 GMT
Believe it or not, I am reading all of this waiting for a lightbulb moment. NOT GETTING INVOLVED THOUGH.
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Post by duwayne on Oct 9, 2018 13:50:19 GMT
If the atmosphere stratified, we would all be dead with our current molecular biology. You are confusing stratified with permanently stratified. On a particular day there are layers for whatever reason - these are visible. The troposphere is a layer of convecting air at the top of this layer convective mixing stops - it is called the tropopause and above it the stratosphere. Even the tropopause is like the surface of any fluid and gets disturbed by waves which can break mixing stratospheric air with tropospheric air. The inversion _layer_ builds as the air cools but is destroyed by convection when the sun warms the surface. Convective currents start for the smallest difference and bubble up just like a lava lamp but invisible. Watch cold water steaming as water evaporates and condenses into the air the steam (small water droplets) _rising_ from the cold surface in the updraft from a lake surface. Fly along between layers of cirro stratus that extend for hundreds of miles. Or sit on a coast in persistent drizzle for days under nimbo stratus rolling in off the sea. Even the sea can be considered stratified with the thermocline marking a temperature layer - that doesn't mean it is impossible for water to move between the layers above and below but it does significantly inhibit such transfers. Sigurdur is clearly referring to the behavior of gases in the part of the earth's system where weather takes place. Your comments seem to be totally irrelevant.
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Post by duwayne on Oct 9, 2018 15:30:38 GMT
Icefisher, I agree that this exchange started with your statement. "Water vapor is lighter than air and water is heavier than air. Water vapor rises and water falls in the air, in general." I am trying to make sure I understand what you are saying. Are you saying that because water vapor has a lower molecular weight than oxygen and nitrogen, it will rise within the atmosphere (troposphere) and because of its lower molecular weight, it will ultimately “float”, or whatever word you would like to use to describe the movement, to the top above the oxygen and nitrogen unless interfered with by the wind? If you want to use different words, do so, but I am trying to find out if you mean that individual gases will stratify based on molecular weight. good suggestion! Water vapor rises because its less dense than the surrounding air and water falls because its denser than the surrounding air? Does that make it more understandable for you? I see what you said. I understand what you are saying with respect to the water and I agree. Someone like Nautonnier might say that the water might not fall because he flew by in an airplane and saw a cloud. But I know what you mean. But with respect to water vapor, I'm still not totally sure what you are saying. If you would limit your statement to a volume of entrapped water vapor, I would know exactly what you are saying because the density can be determined. But if you are talking about water vapor in the open atmosphere each molecule will do its own thing and the molecules will mix in with the other gases. When they mix evenly with the other gases as gases do then there won't be any density differences to do the lifting.
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Post by icefisher on Oct 9, 2018 16:10:38 GMT
good suggestion! Water vapor rises because its less dense than the surrounding air and water falls because its denser than the surrounding air? Does that make it more understandable for you? I see what you said. I understand what you are saying with respect to the water and I agree. Someone like Nautonnier might say that the water might not fall because he flew by in an airplane and saw a cloud. But I know what you mean. But with respect to water vapor, I'm still not totally sure what you are saying. If you would limit your statement to a volume of entrapped water vapor, I would know exactly what you are saying because the density can be determined. But if you are talking about water vapor in the open atmosphere each molecule will do its own thing and the molecules will mix in with the other gases. When they mix evenly with the other gases as gases do then there won't be any density differences to do the lifting. Yes there will be. The water vapor immediately starts transferring heat to the denser gases reducing their density. Its not a case as you suggest that the effect of reducing the density of the water vapor has zero effect on the gases its mixing with. Its extremely easy to confirm this as if it worked as you suggested there would probably be only fog and no clouds. In the atmosphere, water vapor is unique in this respect as it can give off a lot of heat without its temperature dropping.
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Post by duwayne on Oct 10, 2018 15:19:01 GMT
Icefisher, let's change seats and let me propose a statement of how water vapor moves in the atmosphere and you critique it.
Water vapor, like other gases in the atmosphere, moves around with the movements of the parcel of air in which it resides and within the parcel it will diffuse toward an evenly mixed state.
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