Radio waves move through the air the same way light waves do. They just go through
it almost as if it weren't there. Like light, in a vacuum they move in something like straight lines, when viewed on a large scale, and in more fuzzed-out ways when viewed on distances of about a wavelength or less. As with light, they reflect off some materials. Also like light, there are some materials that can absorb radio waves. But while light is absorbed by many materials, radio waves can mostly go right through most of the things around us (like light goes through clear glass). So when the radio waves leave the radio station, they are sent off in every direction, skittering and bouncing all the way to your radio antenna, going right through most trees, walls, etc. that might be in the way.
You may find it odd that radio waves can travel through even a vacuum, unlike say water waves, or other ones you've seen, which are waves in some sort of stuff. It turns out that everything, including light is made out of waves. If they are waves in something, as opposed to basic ingredients of the universe, we don't know what that something is. Mike W.
(published on 10/22/2007)