The type of electromagnetic wave propagation which is effected as a result of reflection in the upper ionosphere of atmosphere is known as:

Options

A. air wave propagation
B. space wave propagation
C. sky wave propagation
D. tropospheric propagation

Answer

To solve the question regarding the type of electromagnetic wave propagation that is affected by reflection in the upper ionosphere of the atmosphere, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Layers of the Atmosphere**:
- The atmosphere consists of several layers: troposphere, stratosphere, mesosphere, and ionosphere.
- The ionosphere is the layer that extends from about 30 miles (approximately 48 kilometers) to 250 miles (approximately 400 kilometers) above the Earth's surface.

2. **Identify the Role of the Ionosphere**:
- The ionosphere is crucial for radio wave propagation. It contains charged particles that can reflect certain frequencies of electromagnetic waves back to Earth.

3. **Consider the Types of Wave Propagation**:
- The question provides four options:
- Air propagation
- Space wave propagation
- Sky wave propagation
- Tropospheric propagation

4. **Analyze Each Option**:
- **Air propagation**: This generally refers to wave propagation through the air without significant reflection.
- **Space wave propagation**: This involves waves traveling directly from the transmitter to the receiver without reflection.
- **Sky wave propagation**: This specifically refers to waves that are reflected off the ionosphere back to Earth.
- **Tropospheric propagation**: This refers to wave propagation that occurs in the troposphere, primarily for short distances.

5. **Select the Correct Answer**:
- Since the question specifically asks about reflection in the upper ionosphere, the correct type of electromagnetic wave propagation is **sky wave propagation**.

### Final Answer:
The type of electromagnetic wave propagation which is affected as a result of reflection in the upper ionosphere of the atmosphere is known as **sky wave propagation**.

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