Middle_Man

Styrofoam is only 1.03, but air is 1? So styrofoam is only 3/100ths more difficult to penetrate than air? Seems a bit odd.

Perhaps air should have been listed as "ozone" or eve "atmosphere"?

Obviously you didn't make the list, but from the point of view of common sense it seems flawed (if only with that one issue).

Air = free space; my point was that styrofoam is basically transparant. And that chart proves it.

You did bring up one point I did fail to mention which is atmospheric attenuation. However, that attenuation is always there and fluctuates only when clouds (water) go in front of it. So on a cloudy day it would be harder to see GPS than on a bright sunny blue sky day.