Deep Dive: E3A07
The correct answer is C: Large bodies of water. Atmospheric ducts capable of propagating microwave signals often form over what geographic feature is large bodies of water. Water bodies create temperature inversions that form ducts. For amateur radio operators, this is important for microwave propagation. Understanding this helps when operating on microwave bands.
Why Other Answers Are Wrong
Option A: Incorrect. Mountain ranges don't typically form ducts - large bodies of water do. Mountain ranges isn't the feature. Option B: Incorrect. Stratocumulus clouds don't form ducts - large bodies of water do. Stratocumulus clouds isn't the feature. Option D: Incorrect. Nimbus clouds don't form ducts - large bodies of water do. Nimbus clouds isn't the feature.
Exam Tip
Atmospheric ducts form over = large bodies of water. Think 'A'tmospheric 'D'ucts = 'A'cross 'D'amp water. Water bodies create temperature inversions that form ducts. Not mountain ranges, not stratocumulus, not nimbus - just large bodies of water.
Memory Aid
Atmospheric ducts form over = large bodies of water. Think 'A'tmospheric 'D'ucts = 'W'ater. Water bodies create temperature inversions that form ducts. Important for microwave propagation.
Real-World Example
Atmospheric ducts for microwave signals: They often form over large bodies of water (oceans, large lakes). The water creates temperature inversions in the atmosphere, which can trap and guide microwave signals beyond the normal horizon. This is the geographic feature - large bodies of water.
Source & Coverage
Question Pool: 2024-2028 Question Pool
Subelement: E3A
Reference: 2024-2028 Question Pool · E3 - Radio Wave Propagation
Key Concepts
Verified Content
Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E3A topic.