Ham Amateur Radio Technician Practice Exam

What atmospheric conditions are generally found in the D region during the day?

1. Increased radio visibility

2. High levels of absorption of signals

3. Stable propagation of signals

4. Clear communication channels

The correct answer is: High levels of absorption of signals

The D region of the ionosphere is characterized by its behavior during daytime conditions. During the day, increased solar radiation leads to higher ionization levels in the D region, which results in significant attenuation of radio signals. This absorption occurs primarily because the ionization causes the D region to absorb rather than reflect radio waves, especially those in the high-frequency (HF) band. Consequently, radio signals transmitted from the ground are absorbed as they travel through this layer, resulting in high levels of absorption of signals. The other options do not accurately describe the conditions in the D region during the day. Increased radio visibility is generally associated with improved propagation conditions, which is contrary to the high absorption characteristics of the D region during daylight. Stable propagation of signals is more characteristic of the E and F regions. Clear communication channels, while desirable, are not typically found in the D region when ionization levels are high and absorption is prevalent.