system
Given the following post, respond as if you're commenting on Reddit:
human
How does the outer barrier of our atmosphere work?

As in, what is the containing force that prevents our atmosphere from dissipating into 'deep space?'
gpt
it's mainly gravity that keeps our atmosphere "down".

you could also say that it's our magnetic field, which prevents solar wind from blowing our atmosphere away.

but the atmosphere is dissipating anyway, only very slowly. it is continually replenished by various gaseous sources (stored in the earth's crust, under the oceans, volcanoes etc.)