Glossary of Solar Terrestrial Terms
X Class Flare
Flares which have a particular range of energy output of X ray radiation. X class flares are very energetic events which will produce short wave fadeouts on HF sky wave circuits with daylight sectors.
Electromagnetic waves of wavelength 0.001 to 1 nm. X rays are emitted during solar flare activity and ionise the D region causing increased absorption of HF radio waves causing daylight fadeouts.