Solar flare is a localized intense eruption of electromagnetic radiation from the Sun's atmosphere. Solar flares increase extreme ultraviolet (EUV) and X-ray energy which causes rapid increase in ionization of the D-layer of the ionosphere. As D-layer of the ionosphere is present on the daytime side of the globe, this can cause complete fading out of dayside HF communications. The problem can last from a few minutes to an hour or sometimes more. As the solar EUV and X-ray energy takes only about 8 minutes to reach the Earth, advance warning of this effect is not possible.
@W9GB has posted on another forum that there was a recent Solar X-flare which is active and Aurora is visible in and South of Greenland. Thought that it is relevant to this thread. Wonder how to follow the data on active Solar flares? I am just exploring heliophysics as a newbie.
The X-rays and ultraviolet rays generated by solar flares can increase the degree of ionization in the ionosphere, leading to thickening and densification of the ionosphere. In this way, the ionosphere's ability to reflect and transmit radio waves will also change, causing interference to shortwave communication
