Offline Cypher9

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Why doesn't the atmosphere drift off into space?
« on: September 23, 2020, 05:44:36 PM »
I asked the same question on YT and received this reply:
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Gas particles move at 0.4km per second. To expand into space, they would need to travel at 11km per second. It's very simple to understand... even for unqualified commoners.

I've no idea how to answer it. I mean it sounds like BS but what do I know. Perhaps someone can tell me if it's factual or not.

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Offline JSS

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Re: Why doesn't the atmosphere drift off into space?
« Reply #1 on: September 23, 2020, 05:59:40 PM »
I asked the same question on YT and received this reply:
Quote
Gas particles move at 0.4km per second. To expand into space, they would need to travel at 11km per second. It's very simple to understand... even for unqualified commoners.

I've no idea how to answer it. I mean it sounds like BS but what do I know. Perhaps someone can tell me if it's factual or not.

I'm not sure where they got the 0.4km second figure.  That's 1118 mph!  I'm pretty sure when I breathe the air isn't rushing in and out of my lungs faster than the speed of sound.

I'd start by asking where they got that number.

Offline Cypher9

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Re: Why doesn't the atmosphere drift off into space?
« Reply #2 on: September 23, 2020, 06:04:03 PM »
But aren't you 'pulling' the air into your mouth when you breath?

Re: Why doesn't the atmosphere drift off into space?
« Reply #3 on: September 23, 2020, 06:06:39 PM »
A few basic ideas need to be understood to look at the question. I'm not an expert, but consider looking into some of these:

- gravity is the main thing holding our atmosphere in place. The 11km/s quote is the speed required for something to leave earth's orbit.

-gases can only push. They flow from areas of high pressure to areas of low pressure

- gravity exerts a force that stratifies our atmosphere into different layers, but generally speaking, more atmosphere is held closer to the earth than high up above it. Atmospheric pressure is greatest at sea level and gets exponentially lower as you gain altitude. This means that the higher up you go, the closer the atmospheric pressure gets to zero. At the boundary between earth's upper atmosphere and "space", atmospheric pressure is almost zero. This means that there is no pressure gradient to cause the gas to be lost to space

- earth is constantly losing parts if its upper atmosphere to space though, from interactions with the solar wind. If it wasnt for our magnetic field, we would lose atmosphere at a much greater rate (mars no longer has a magnetic field, which is believed to be a major cause of why it has such a thin -low pressure- atmosphere). Despite losing little bits of atmosphere, were constantly gaining 'new atmosphere's through volcanic eruptions, weathering processes, and biosphere interactions.

Again, dont take my word... I've undoubtedly oversimplified things. But dive in to some of those concepts and come up with an answer for yourself!
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Offline Cypher9

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Re: Why doesn't the atmosphere drift off into space?
« Reply #4 on: September 23, 2020, 06:18:17 PM »
Ok, thanks.