G3A02:

What effect does a Sudden Ionospheric Disturbance have on the daytime ionospheric propagation of HF radio waves?

  1. It enhances propagation on all HF frequencies
  2. It disrupts signals on lower frequencies more than those on higher frequencies
  3. It disrupts communications via satellite more than direct communications
  4. None, because only areas on the night side of the Earth are affected