Basic Qualification · B-007 Radio wave propagation · B-007-007-003
What causes tropospheric ducting of radio waves?
- A A very low-pressure area
- B A temperature inversion
- C transmitting
- D An aurora to the north
Correct answer: B — A temperature inversion. From the official ISED question bank, verified word for word.
Why
A temperature inversion happens when a layer of warm air sits above cooler air near the ground, creating a duct that traps and guides radio waves over long distances instead of letting them escape into space. The full explanation — and one for every question — is in Pro.
Practise this section
How signals travel: the ionosphere and its layers, skip, ground wave, sporadic E, and which bands work when.