Ok, so I was doing some math here. (Maths if you speak the "Queen's English")
Let's say that Ormal is in South Africa, putting Almaren somewhere in Egypt. Distance is about 4000 miles, or almost 6500 km.
If there is even a single mountain of a mile high (not by any means super tall) or 1.6 km between Almaren and Ormal, Ormal has to be about 3.5 miles, or 5.6 km just to be visible over it.
That's not even taking into account that Tolkien says that the lamps are "more lofty far than are any mountains of the later days."
So let's just say, Mt. Everest for example: 29,029 feet, 8.848 km, or 5.5 miles.....
I'd say we're looking at 5-6 mile high towers, folks.