Extra exam question E3C12
Subelement E3, RADIO WAVE PROPAGATION· Group E3C
Which of the following is indicated by a sudden rise in radio background noise across a large portion of the HF spectrum?
- A.A temperature inversion has occurred
- B.A coronal mass ejection impact or a solar flare has occurred (correct answer)
- C.Transequatorial propagation on 6 meters is likely
- D.Long-path propagation on the higher HF bands is likely
WhyA sudden rise in radio background noise across a large portion of the HF spectrum indicates a coronal mass ejection impact or a solar flare has occurred. A sudden, widespread rise in HF background noise typically signals that a coronal mass ejection has struck Earth's magnetosphere or that a solar flare has just occurred, both of which can flood the HF spectrum with added noise and disturbance, answer B. A tropospheric temperature inversion is a VHF/UHF ducting phenomenon, not an HF noise source, and this kind of sudden broadband noise rise doesn't specifically predict 6-meter TEP or higher-band long-path openings.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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