Helium Loss

[gamowin]

So I hear that we are running out of helium, and that makes sense because it has a very low density. But doesn't it just form a new thin layer of atmosphere made of helium like oil on water? I don't understand why some people suggest helium rigs up in gas giant's upper atmosphere. When you pour oil into water, the oil doesn't get flung away, so why would helium?

[Kryten]

We don't get helium from the atmosphere, we get it from reserves trapped along with natural gas deposits, and most of the helium-rich ones are nearly tapped out.

[MGUARN]

Helium is so light that it basically leaves the atmosphere.Shortest term ... Helium floats out into space.If im right.

[astropapi1]

The "Solar wind" takes it away.

[PringleMan]

The problem with light gasses is that unless there is a strong gravitational force they will just float away into space. Solar winds help this because if the gasses are at high altitudes (barely held) but there is insufficient magnetic field to deflect solar winds, then they will get blown off through particle interactions.

This is suggested as one of the reasons for the stripping of the martian atmosphere. It is fairly clear it was much thicker in the past, and it is believed that one cause for the thinning was internal cooling of the core weakening the planetary magnetic field and causing irregularities. Solar wind would be able to penetrate to lower altitudes, and impart enough energy to gasses to cause them to escape. This sensibly would leave heavier gasses such as carbon dioxide, the current main component of the martian atmosphere.

[Kerbface]

Think of it less like oil on water and more like water on skin or something. It evaporates over time, because firstly the higher energy molecules simply fly out, and secondly the wind makes it much easier to blow away. It's like that with atmospheric gases, particularly lighter ones. Except the wind is solar.

[LeathalMeatball]

Helium is acted upon by gravity just like all other gasses present in our atmosphere, it wont escape earth's gravitational influence just because its less dense than other atmospheric gasses.

[Kryten]

Helium is acted upon by gravity just like all other gasses present in our atmosphere, it wont escape earth's gravitational influence just because its less dense than other atmospheric gasses.

Look up something called the 'kinetic theory of gases'. You're welcome.

[Brotoro]

Helium is acted upon by gravity just like all other gasses present in our atmosphere, it wont escape earth's gravitational influence just because its less dense than other atmospheric gasses.

The speed at which atoms or molecules move in a gas depends on their atomic or molecular weight. Helium has a low atomic weight, so it moves faster (at the same temperature) than heavier molecules like oxygen and nitrogen and carbon dioxide. Therefore helium can easily escape from the Earth's atmosphere.