Scientists have proposed the first ever quantitative description of the mechanism responsible for sunspot formation and underlying the solar activity cycle. Magnetic field helicity is one of the so-called motion invariants in magneto-hydrodynamics. It is a conserved quantity, like energy, describing the degree to which the field lines are “wrapped around themselves”. During the last 20 years, scientists realized that conservation of this quantity is even more influential upon magnetic field evolution than energy conservation.
from Space & Time News — ScienceDaily http://ift.tt/1htVgID