*Question E3A07:
Atmospheric ducts capable of propagating microwave signals often form over what geographic feature?*  

*Correct Answer is  C: Large bodies of water*  

### AI Response: (may contain errors)  

Atmospheric ducts that can propagate microwave signals typically form over large bodies of water. Here's a breakdown of why this is the correct answer and why the other options are not:

### Correct Answer: Large bodies of water
- **Reason**: Large bodies of water, such as oceans or lakes, have a relatively stable temperature and humidity profile. This stability can create a temperature inversion, where warmer air sits above cooler air. This inversion layer can trap microwave signals, allowing them to travel longer distances than they would in normal atmospheric conditions.

### Why the Other Choices Are Incorrect:
- **A: Mountain ranges**
  - **Reason**: While mountain ranges can influence weather patterns and create some forms of propagation, they do not typically create the stable temperature gradients necessary for ducting microwave signals. Instead, they can cause scattering and reflection of signals.

- **B: Stratocumulus clouds**
  - **Reason**: Stratocumulus clouds are low, lumpy clouds that do not create the necessary conditions for ducting. They are often associated with stable air but do not provide the temperature inversion needed for effective microwave propagation.

- **D: Nimbus clouds**
  - **Reason**: Nimbus clouds are associated with precipitation and unstable atmospheric conditions. They do not create the stable layers required for ducting and can actually absorb and scatter microwave signals rather than propagate them.

### Summary
- **Ducting** occurs primarily over large bodies of water due to stable temperature inversions.
- Mountain ranges, stratocumulus clouds, and nimbus clouds do not provide the same conditions for effective microwave signal propagation.

This understanding of atmospheric conditions is crucial for predicting and optimizing microwave communication systems.