Board Thread:Lore Discussion/@comment-72.27.127.103-20150320015853/@comment-9212235-20150326144524

It is definitely literally clockwork. Also, the heat can be attributed to magicka. Nirn (and the other planes) were created using creatia (magicka) and it is infused with it. It gives off its own heat similarly to earth. And similarly still, most of its magicka (heat) comes from Magnus (the sun).