SKY WAVE OR IONOSPHERIC PROPAGATION ?

Explanation

### Step-by-Step Solution

1. **Understanding the Atmosphere**:
- The Earth is surrounded by an atmosphere that extends to about 1000 kilometers. Within this atmosphere, there exists a layer known as the ionosphere.

**Hint**: Remember that the ionosphere is a region of the atmosphere that contains ions and free electrons, which play a crucial role in radio wave propagation.

2. **Defining the Ionosphere**:
...