Well, it wouldn't matter, Category-rated cable is for indoor use only (Avaya is the only exception that I'm aware of, they do make an external-rated Cat5, but it's actually meant to be in conduit). There's no valid reason from running Cat-(anything) outside of a building: it's dangerous to living and electronic things.
UV (and some other atmospheric anomilies) is stronger at higher elevations. Chek out
Space Weather Now.
If you click on some of the links for the various alerts, some are rated as being more critical at higher altitudes.
FWIW
Scott