ATPL EASA Radio Navigation Practice Exam 2025 – All-in-One Guide to Master Your Certification!

The process characterized by waves that follow the surface of the Earth is known as diffraction. When waves encounter an obstacle or a slit that is comparable in size to their wavelength, they bend around the edges of the obstacle or spread out after passing through the slit. This bending allows the waves to effectively follow the contours of the Earth’s surface, which is particularly relevant in various applications such as radio wave propagation over long distances.

In contrast, reflection involves a change in direction of the waves when they bounce off a surface; absorption refers to the loss of energy as waves pass through a medium; and refraction involves the bending of waves as they pass from one medium to another due to a change in speed. These processes do not specifically describe the characteristic of following the Earth’s surface as diffraction does. Understanding this principle is essential in radio navigation, as it affects how signals can propagate and be received over distances.