Type II solar radio bursts are the result of energetic electrons accelerated by a shock. This kind of burst appears on dynamic spectra as lanes drifting slowly from higher to lower frequencies. Often, scientists observe a fundamental harmonic structure, which sometimes exhibits a division on each band called band split.
![](https://3c1703fe8d.site.internapcdn.net/newman/csz/news/tmb/2019/detectionofs.jpg)
Source:
https://phys.org/news/2019-07-spike-like-front-shock-driven-solar-radio.html