The
writeup above is partly correct but it is not complete.
When the magnetic field lines of the sun get very twisted they can pop out creating sunspot pairs. These are
loops of magnetic field lines that takes in and return plasma to the sun. If a
magnetic fields line gets very very twisted, or it pops up with a great amount of force, it may not be able to form a loop. In this case the line just leads out into space. When this happens it gives plasma an elevator to freedom. The
plasma can travel along the line and make its way out into space where it becomes the solr wind.
The
coronal holes mentioned above are these single
sunspots not the more common pairs.
To find out about the
coronal holes check under that node