I think the aura extending to cover passengers is a fanfic convention. I don't think that series ever mentioned it, nor do I remember the comics bringing in up.
Lois has expressed the fact that she was cold when he took her up to see 'his world' above the clouds, so he wrapped her in his cape.
Personally, I don't think the writers really gave the idea any thought, so whatever worked for the story was the way they let it go.
Tank (who found that consistancy was not necessarily a strenght of the television writers)
