3.6 Type IV radio bursts
Some of these impulsive high-frequency microwave bursts are accompanied by long-lived radio
enhancements at lower frequencies. Such type IV radio bursts cover a continuous spectrum with frequencies
below 200 MHz, i.e., in the meter wavelength range. Sometimes their sources are seen to move away from
the Sun. These moving type IV bursts were thought to be caused by electrons trapped in a closed magnetic
cloud ejected from the flare site, but this interpretation is still under debate. For more information see, e.g.,
Švestka (1981) or Kahler (1992).