April 07, 2015
BOULDER – The Sun undergoes a type of seasonal variability, with its activity waxing and waning over the course of nearly two years, according to a new study by a team of researchers led by the National Center for Atmospheric Research (NCAR). This behavior affects the peaks and valleys in the approximately 11-year solar cycle, sometimes amplifying and sometimes weakening the solar storms that can buffet Earth’s atmosphere.
The quasi-annual variations appear to be driven by changes in the bands of strong magnetic fields in each solar hemisphere. These bands also help shape the approximately 11-year solar cycle that is part of a longer cycle that lasts about 22 years.
Read more of the original article here: http://www2.ucar.edu/atmosnews/news/15037/sun-experiences-seasonal-changes-new-research-finds