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If a gas is 5 times heavier than air, how can it be a greenhouse gas? Can someone explain how it gets up there if it's so dense.
The guy running the course can't.
I thought greenhouse gas wasn't a real thing.. Greenhouse gas would really be CO2 and H2O which is everywhere, no particular altitude... But I really don't know for sure.
[url= http://en.wikipedia.org/wiki/Greenhouse_effect ]Greenhouse effect Wiki[/url]
I would say mixture by Diffusion, brownian motion, wind, thermals, but I am not an expert.
Air is a mixture of different gases with a density of around 1.225 kg/m3 at sea level/15c but this is an average of all the gases in the air, which all mix in together. On a teeny tiny local scale the air density varies quite widely due to local variations in temp/pressure/gas constituents.
For example air is made of
21% O2 @ 1.225 kg/m3
78% Nitrogen @ 1.19 kg/m3
and 1% loads of other gases at lots of different densities.
So Ozone is 2.14 kg/m3 and CFC's vary from 1.3-2.14 and are greenhouse gases. Which gas has 5 times the density of air?
Can someone explain how it gets up there if it's so dense.
Methinks you're confusing the Ozone layer with the Greenhouse effect. The Ozone is "up there' (although there's a lot of it down here also which is a pollution hazard), but the greenhouse effect is a result of the relative proportions of different gasses in the atmosphere in general - not a specific layer at some particular height.
Or, conversely, would the OP expect the atmosphere to be stratified by density?
Not confusing it with ozone. This gas has on chlorine component so has nothing to do with the ozone layer.
The gas in question is sulphurhexaflouride.
Gases in the atmosphere are constantly mixed by a number of different mechanisms, the wind being the most obvious one. That's how it can be present in the atmosphere. It's no different from CO2 in that regard, only in scale.
sulphurhexaflouride has no Chlorine in it
It's the same way that boats (made of steel n iron n stuff) can float on water. I think.
Think of the atmosphere like a solution. Overtime SF6 would diffuse to an even coverage.
Have you ever seen a plastic bag or sheet of paper flying through the air? They are hundreds of times denser than the gases you refer to. The greenhouse gases will diffuse into the air like solids diffuse into liquids. There's so much movement at molecular & macro scales to spread the gases evenly.
Have you ever seen a plastic bag or sheet of paper flying through the air? They are hundreds of times denser than the gases you refer to. The greenhouse gases will diffuse into the air like solids diffuse into liquids. There's so much movement at molecular & macro scales to spread the gases evenly.
Similarly you have dust in the atmosphere - thats what gives us a lovely red sunset and those particles are also point that raindrops and snow snowflakes form around. But as pieces of solid material they're much denser than any of the gases they're getting churned around in.
A green house gas is so named because of its ability to reflect and re-emit infra red radiation. This is not altitude specific. The height at which you find it is not relevant to it's classification as a greenhouse gas.
Diffusion, mixing and entropy.
Ignoring the greenhouse bit.
In a stable environment the two gases would be separate, however, while I can't be arsed to sit down and work it out, there would be some mixing through brownian motion and they may well mix completely if the entropy is favourable? Timescale, geological?
In a turbulent environment like the atmosphere there would be energy around to mix them (weather) and then they may settle out over time if the effects of gravity vs entropy were great enough (again, I can't be bothered to think too hard about that). It would also depend on how miscible they were and other things kicking around to make mixing more favourable.
Think of a more common example. Alcohol, a.k.a. Ethanol, is less dense than water. If you were really careful you might be able to get a layer of pure alcohol on top of water. However, vodka doesn't phase separate into tow layers on the shop shelf.
while I can't be arsed to sit down and work it out, there would be some mixing through brownian motion and they may well mix completely if the entropy is favourable? Timescale, geological?
Isn't there a long running experiment to this effect by Kelvin still Brownian-ing away in Glasgow?
Water vapour is one of the most effective greenhouse gasses, IIRC.