Nick -Eric Charles
I'd like to interject here that your original question about the mixing (or not) of atmospheric components was a very legitimate question...
I hope (many) of the responses you got (Bruce's in particular) helped dispel the mystery of what we all know circumstantially (though I'm not sure most of us would notice if the O2 levels were elevated after a quiet, still night?).
While I may personally have some specific experience (as anecdotally described) with the formalities of these problems I think it is assumed that most of us here do not!
The innocence of many of your questions as posed should be more overtly valued... many of us are busy asking (quietly) similar or related questions.
Don't let the unregulated banter that follows some of your questions be mistaken for anything but what it is, a good excuse for banter... Doug and I perhaps being the worst of the crowd for that.
So... I say let the discussion of mixtures and solutions and miscibility continue... I have to admit that I have a "working" knowledge of miscibility but not enough understanding of it's foundations!
- SteveSS wrote:
But are you surprised that your bottle of wine, beer, or hard liquor hasn't seperated before you even get to pour it?
NST REPLIES:
Well I guess I am surprised by that. Whiskey (etc) is just a mixture of alcohol and water,no? I suspect that there is some sort of distinction lurking here between a “solution” of something and a “mixture” of something.
From: friam-bounces@... [mailto:friam-bounces@...] On Behalf Of Steve Smith
Sent: Tuesday, June 12, 2012 3:45 PM
To: The Friday Morning Applied Complexity Coffee Group
Subject: Re: [FRIAM] atmospherics
Nick -
I think Bruce just gave a good calibration on this with his great description not only of why or why not to breathe Uranium Hexaflouride (cuz you will have to stand on your head to empty it from your lungs!) but also the relative density of the gasses in question.
Try the analogy of mixed drinks. Every good bartender knows that you put the alcohol into the glass first so that when you add the water-based stuff (tonic, seltzer, juice, etc.) the two mix naturally. If you pour the alcohol *over* the watery things, you risk the alcohol "floating" rather than mixing. We could go into the implications of low and high "proof" alcohol, etc.
But are you surprised that your bottle of wine, beer, or hard liquor hasn't seperated before you even get to pour it?
AS I think Doug mentioned, thermal energy alone is a good mixer... even without the constant stirring of wind and convection...
- SteveSorry. Mixed up the weight of N and O. So my question should have been, Why don’t we wake up in a layer of oxygen on still nights?
Which brings us to your question about what would make me expect that a mixture would separate out into its lighter and heavier components. You tell me! Other things being equal, don’t heavier things tend to sink when mixed with lighter ones?
N
From: friam-bounces@... [mailto:friam-bounces@...] On Behalf Of Douglas Roberts
Sent: Tuesday, June 12, 2012 2:43 PM
To: The Friday Morning Applied Complexity Coffee Group
Subject: Re: [FRIAM] atmospherics
Let's not ignore temperature: my farts are a good 20 degrees F above ambient (at present), and tend to rise before mixing into the unfortunate nearby environs. And, just in case you were wondering what the composition of a fart was:
The major components of the flatus, which are odorless, by percentage are:<a moz-do-not-send="" href="http://en.wikipedia.org/wiki/Flatulence#cite_note-3" onclick="window.open('http://en.wikipedia.org/wiki/Flatulence#cite_note-3');return false;">[4]
§ <a moz-do-not-send="" href="http://en.wikipedia.org/wiki/Nitrogen" title="" onclick="window.open('http://en.wikipedia.org/wiki/Nitrogen');return false;">Nitrogen: 20–90%
§ <a moz-do-not-send="" href="http://en.wikipedia.org/wiki/Hydrogen" title="" onclick="window.open('http://en.wikipedia.org/wiki/Hydrogen');return false;">Hydrogen: 0–50%
§ <a moz-do-not-send="" href="http://en.wikipedia.org/wiki/Carbon_dioxide" title="" onclick="window.open('http://en.wikipedia.org/wiki/Carbon_dioxide');return false;">Carbon dioxide: 10–30%
§ <a moz-do-not-send="" href="http://en.wikipedia.org/wiki/Oxygen" title="" onclick="window.open('http://en.wikipedia.org/wiki/Oxygen');return false;">Oxygen: 0–10%
§ <a moz-do-not-send="" href="http://en.wikipedia.org/wiki/Methane" title="" onclick="window.open('http://en.wikipedia.org/wiki/Methane');return false;">Methane: 0–10%
4. <a moz-do-not-send="" href="http://en.wikipedia.org/wiki/Flatulence#cite_ref-3" onclick="window.open('http://en.wikipedia.org/wiki/Flatulence#cite_ref-3');return false;">^ <a moz-do-not-send="" href="http://www.britannica.com/eb/article-45361/human-digestive-system#294193.hook" onclick="window.open('http://www.britannica.com/eb/article-45361/human-digestive-system#294193.hook');return false;">"Human Digestive System". Encyclopædia Britannica. Retrieved 2007-08-22.
--Doug
On Tue, Jun 12, 2012 at 12:33 PM, Roger Critchlow <rec@...> wrote:
Nick --
N2 weighs 28 gm/mole, O2 weighs 32 gm/mole, Ar weighs 40 gm/mole, CO2 weighs 44 gm/mole, and H2O weighs 18 gm/mole.
Why would anyone expect the lighter components of a mixture to fall down more than the heavier ones? If anything, you'd expect the heavier ones to concentrate toward the bottom.
And why would anyone expect a mixture to spontaneously separate into pure components? That happens in real life like where?
As it happens, CO2 is the heaviest normal component and it does pool in confined spaces often enough that CO2 alarms are available in hardware stores. Propane, C3H8, weighs 44 gm/mole and is notorious for pooling in confined spaces and then exploding, often in the bilge of a boat and spectacularly.
-- rec --
On Tue, Jun 12, 2012 at 10:44 AM, Nicholas Thompson <nickthompson@...> wrote:
So, somebody asked me, in my role as a weather nerd, how come the nitrogen in the atmosphere doesn’t all fall to the bottom on still nights and suffocate us all. I asked the question of <a moz-do-not-send="" href="http://stupid-answers-to-stupid-questions-asked-by-stupid-people.com" target="" onclick="window.open('http://stupid-answers-to-stupid-questions-asked-by-stupid-people.com');return false;">stupid-answers-to-stupid-questions-asked-by-stupid-people.com and THEY said, well, there’s just too much going on. N molecules and the O molecules are just too busy, what with convection and windcurrents, and all, to separate, even on still nights. Now, that business doesn’t prevent cold molecules of Nitrogen and Oxygen to separate from warm ones, or wet ones (not sure what that means) to separate from dry ones. I was hoping that somebody on FRIAM could give some sort of a clue what kind of a mixture AIR is? It is suddenly seeming kinda special.
Nicholas S. Thompson
Emeritus Professor of Psychology and Biology
Clark University
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