Does anyone know if any conditions change with altitude on the Outlands? Does the air get thinner? Does it get colder? If so, is there any idea why?
I found myself asking this last night as I tried helping my DM flesh out a culture, and I can't for the life of me find any information online. (And I've certainly never encountered any information in the books I've read.) Thoughts on the subject would be appreciated! I signed up here just to ask. 
I dont think there was anything written about that for the outlands. You could check planeswalker.com