An ejection of material from the sun into interplanetary space. If the material is directed toward Earth, then the event is associated with a disturbance to the Earth's magnetic field or ionosphere. At times, the whole HF spectrum is affected, but normally the lower frequencies are affected most. Only those circuits with daylight sectors can be affected. An explosion on the sun usually releasing large amounts of energy and particles, and usually occurring within an active region.
Flares are more likely at solar maximum.
Solar flares, which have a particular range of energy output of X-ray radiation. An M class flare will usually produce a short-wave fadeout in the daylight hemisphere of the Earth. M class flares are less intense than X class flares, but more intense than C class flares. The outer magnetic field of the Earth. The magnetosphere is buffeted by the solar wind.