Which of the following is typical of the lower HF frequencies during the summer?
The correct answer is D: High levels of atmospheric noise or static. What is typical of the lower HF frequencies during the summer is high levels of atmospheric noise or static. Summer brings more thunderstorms and atmospheric activity, creating more static on lower frequencies. For amateur radio operators, this makes lower bands noisier in summer. Understanding this helps explain seasonal propagation characteristics.
Exam Tip
Lower HF in summer = high atmospheric noise/static. Think 'S'ummer = 'S'tatic 'S'evere. Summer brings more thunderstorms and atmospheric activity, creating high levels of static on lower HF frequencies. Not poor propagation, not worldwide daylight, not photon absorption - just high noise.
Memory Aid
"Lower HF in summer = high atmospheric noise/static. Think 'S'ummer = 'S'tatic 'S'evere. Summer brings more thunderstorms and atmospheric activity, creating high levels of static on lower HF frequencies. Typical summer characteristic."
Real-World Application
You operate on 80 meters during summer. The band is very noisy with atmospheric static from thunderstorms. Summer brings more convective activity and thunderstorms, creating high levels of atmospheric noise on lower frequencies. The band may still work, but the noise level is high, making weak signals harder to copy.
Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Lower HF frequencies don't have poor propagation at any time - they often work better in summer due to less D-layer absorption. Propagation can be good, just noisy.
Option B: Incorrect. Lower HF frequencies don't have worldwide propagation during daylight - they're better at night. Worldwide daylight propagation is for higher bands.
Option C: Incorrect. Heavy distortion from photon absorption isn't typical - that's not how lower frequencies work. The issue is atmospheric noise, not photon absorption.
题目解析
The correct answer is D: High levels of atmospheric noise or static. What is typical of the lower HF frequencies during the summer is high levels of atmospheric noise or static. Summer brings more thunderstorms and atmospheric activity, creating more static on lower frequencies. For amateur radio operators, this makes lower bands noisier in summer. Understanding this helps explain seasonal propagation characteristics.
考试技巧
Lower HF in summer = high atmospheric noise/static. Think 'S'ummer = 'S'tatic 'S'evere. Summer brings more thunderstorms and atmospheric activity, creating high levels of static on lower HF frequencies. Not poor propagation, not worldwide daylight, not photon absorption - just high noise.
记忆口诀
Lower HF in summer = high atmospheric noise/static. Think 'S'ummer = 'S'tatic 'S'evere. Summer brings more thunderstorms and atmospheric activity, creating high levels of static on lower HF frequencies. Typical summer characteristic.
实际应用示例
You operate on 80 meters during summer. The band is very noisy with atmospheric static from thunderstorms. Summer brings more convective activity and thunderstorms, creating high levels of atmospheric noise on lower frequencies. The band may still work, but the noise level is high, making weak signals harder to copy.
错误选项分析
Option A: Incorrect. Lower HF frequencies don't have poor propagation at any time - they often work better in summer due to less D-layer absorption. Propagation can be good, just noisy. Option B: Incorrect. Lower HF frequencies don't have worldwide propagation during daylight - they're better at night. Worldwide daylight propagation is for higher bands. Option C: Incorrect. Heavy distortion from photon absorption isn't typical - that's not how lower frequencies work. The issue is atmospheric noise, not photon absorption.
知识点
Lower HF frequencies, Summer, Atmospheric noise, Static
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.