Bush's little "ranch"

This is an aerial view of Bush's "ranch" in Crawford Texas.

What jumped off the screen to me was, although there's a huge house and guest house, the staff have to live in trailers.

Gawd he's such an ass.

Oh yeah, why is aerial spelled that way? Why isn't it airial as in from the AIR? I'm so confused by this language.

Thank you to m-w.com for all your help.