They are associated with locations on the sun where magnetic fields are getting tangled to eventually produce flares. These flares accelerate particles away from the Sun, and when some of these encounter the Earth, they can affect the density of electrons in the ionosphere changing its reflectivity, and the way that radio waves propagate.
All answers are provided by Dr. Sten Odenwald (Raytheon STX)
for the
NASA IMAGE/POETRY
Education and Public Outreach program.