The solar disk is hidden by a cache with angular dimension twice that of the Sun (coronograph). The intensity is a measure of the density of the coronal plasma. The white flames (or "coronal streamers") are thus denser regions; they form generally at places where the magnetic field lines have closed structures which emprison the plasma and prevents the gas from flowing away.

Hence, contrary to what suggests their name ("streamers"), the wind starts flowing outside these white regions, in the dark regions in between the streamers.

The picture has been made during a period maximum solar activity (which comes back every 11 years). During maximal activity, coronal streamers appear at all latitudes around the Sun. On the contrary, at other periods, streamers cluster preferentially around low latitudes (below).

Solar Corona during an eclipse, at minimum solar activity