Real mixed bag of questions today. Also I said Nitrogen instead of Hydrogen. I was thinking of the atmosphere and not the earth as a whole.
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https://www.youtube.com/watch?v=OcY4CHf7itY
I hope this explains it well, maybe I should try to make a vid when my sinuses aren't wrecking my brain.
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https://www.youtube.com/watch?v=BIISq9x4cIU