On the way down it's easy: because the air compresses and heats up to the point it becomes a plasma. And despite that we associate it with a glow, it's actually

On the way down it's easy: because the air compresses and heats up to the point it becomes a plasma. And despite that we associate it with a glow, it's actually perfectly dark (there are free electron bands in it). In other words: it blocks every frequency, and lasers, if you want to go line of sight. Now you can get better quality with better receivers/transmitters, but I guess it takes a lot of engineering they didn't do yet.