When is the EDF error associated with night effect greatest?

The EDF (Equivalent Distance Factor) error associated with night effects is greatest at higher frequencies due to the behavior of radio waves in different atmospheric conditions. At night, the ionosphere can reflect signals differently compared to daytime, primarily affecting higher frequencies that are more susceptible to these variations. This can lead to issues such as increased signal distortion and variations in range and quality, making the reception of higher frequency transmissions more challenging during night operations.

As frequency increases, the wave's ability to penetrate the atmosphere decreases, resulting in a reliance on sky wave propagation, which is influenced by the ionosphere's conditions. Thus, the nature of night effects emphasizes this disparity in performance across frequencies, with higher frequencies being more adversely affected.