A cross-section of the solar atmosphere 40 000 kilometres above the solar surface and 110 000 kilometres wide
(shown as a vertical strip) changes over a period of 4 hours (horizontal scale) as observed by SUMER on SOHO
in the ultraviolet light from strongly ionised iron atoms (Fe XIX, 1118 angstroms).
Left: brightness.
Right: motion towards us (blue) and away (red).
Rapid injections of energy repeatedly lead to flashes of extremely hot emission and vibrations that quickly die out.