That might cause pools of liquid nitrogen mighten it?

"John Popelish" wrote in message
...
Rodney Kelp wrote:

How do you get a nitrogen atmosphere from a moon that has methane oceans?

It is so cold that the methane does not have a very high vapor
pressure, so the atmosphere can keep only a little mixed in as vapor
before it rains out. Nitrogen is left. If it was a bit colder, that
would rain out, too.

--
John Popelish