Theoretical so far, but I have witnessed in desert camping that as the day drew on hot, the mountains off to the distance seemed to grow in size. My assumption being that the opposite would be true for a colder climate. I think the NSDAP party as on to something with the hollow earth shit. https://www.youtube.com/watch?v=Xm9EwoNdy6k There is a lot of info that supports some type of massive underground cave systems that can be viewed as either another world, or just some massive hollow caverns that possible pre-adamites or some antediluvian bloodlines may of survived.