Possibly it’s time for a recap. The reason why the behaviour of radar is so significant is it proves the world has curvature. Why is that the case? Radar waves propagate outward at the speed of light keeping travelling until they bounce off something in their way and reflect backward to their point of origin where the signal is picked up by a receiver. Every ship that goes to sea is equipped with radar down even to small craft. The fact is the range of radar is limited, not due to the radar waves themselves that travel in a straight line but due to the curvature of the Earth and how ships at sea will drop below the horizon which results in the radar waves passing over them, due to their no longer being line of sight as far as the radar is concerned. This is why larger vessels with higher superstructure generally can see farther and small craft are harder to detect. The composition of the atmosphere has no or little effect as radar waves will happily pass through air, vacuum or water in the case of sonar. While radar wont detect a ship 100 miles away from its source it will happily bounce signals of very distant objects such as the moon. This fact is a difficult if not impossible one for flat earth believers to come to terms with as its not subject to any conspiracy go ask anyone with a small boat about their experience of using radar.