Page "Sunspot" Paragraph 31

Magnetic pressure should tend to remove field concentrations, causing the sunspots to disperse, but sunspot lifetimes are measured in days or even weeks.

Recent observations from the Solar and Heliospheric Observatory ( SOHO ) using sound waves traveling below the Sun's photosphere ( local helioseismology ) have been used to develop a three-dimensional image of the internal structure below sunspots ; these observations show that there is a powerful downdraft underneath each sunspot, forming a rotating vortex that concentrates the magnetic field.

Sunspots can thus be thought of as self-perpetuating storms, analogous in some ways to terrestrial hurricanes.