That's what I was thinking. It's a variation on a known theme, but it can't be done on Earth, insofar as we know.
It would require one of: * a planet with an oscillating atmosphere that changed composition periodically * a planet with different atmospheres in different places * a way of creating small areas of a different atmosphere than the usual * migrating from a planet with one type of atmosphere to a planet with a different one ... or something of the sort.
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dancing_serpent
Yes ...
Date: 2021-07-13 02:20 am (UTC)It would require one of:
* a planet with an oscillating atmosphere that changed composition periodically
* a planet with different atmospheres in different places
* a way of creating small areas of a different atmosphere than the usual
* migrating from a planet with one type of atmosphere to a planet with a different one
... or something of the sort.