Why are short-waves used in long distance broadcasrs?

Answer 1

Long-distance radio waves are particularly affected by the E and F layers of Earth's ionosphere, causing them to be refracted and reflected back to Earth at a much farther distance or range than they would travel along the Earth's surface. The Earth's surface often reflects the radio waves back up to the ionosphere, where they are again refracted and reflected back to Earth, adding another large distance to their range