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s_86

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nuclearalchemist

You pretty much hit it on the head, everything isn't in equilibrium, and so it always moves around and mixes. You do get layers in the atmosphere for other reasons, but yeah.

MetroidZoid

Argon is a fickle mistress

s_86

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musanman

s_86 wrote: »

nuclearalchemist wrote: »

You pretty much hit it on the head, everything isn't in equilibrium, and so it always moves around and mixes. You do get layers in the atmosphere for other reasons, but yeah.

What if I sealed a tiny jar of air. And the air in that jar did not change temperature, and the jar didnt move. Would that air in there separate into layers?

this is exactly how some wine people preserve their wine. You pump argon into your bottle of wine and it settles since it's heavier than oxygen, and that layer of argon keeps the wine from going bad because the oxygen isn't getting to it.

s_86

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Fuzzy Cumulonimbus Cloud

Isn't Dalton's law of partial pressures wonderful?!

shadydentist

Hmm... on the other hand, you *can* fill a fishtank with a heavier gas like Sulfur Hexaflouride, and 'float' a small boat on top of it.

L|ama

It happens because the sun heats the atmosphere unevenly and you get wind mixing everything up, but otherwise it would separate into layers by molecular weight. This actually happens above a certain point in the atmosphere:

Wikipedia wrote:

The homosphere and heterosphere are defined by whether the atmospheric gases are well mixed. In the homosphere the chemical composition of the atmosphere does not depend on molecular weight because the gases are mixed by turbulence. The homosphere includes the troposphere, stratosphere, and mesosphere. Above the turbopause at about 100 km (62 mi; 330,000 ft) (essentially corresponding to the mesopause), the composition varies with altitude. This is because the distance that particles can move without colliding with one another is large compared with the size of motions that cause mixing. This allows the gases to stratify by molecular weight, with the heavier ones such as oxygen and nitrogen present only near the bottom of the heterosphere. The upper part of the heterosphere is composed almost completely of hydrogen, the lightest element.

So you have the layer below 100km being everything all mixed up, then a layer of oxygen and nitrogen, then nothing but hydrogen the rest of the way out.