7:15 AM | *An update on solar cycle 25 and its impact on cosmic rays* — Arcfield Weather

Solar cycle predictions

Solar cycle predictions are used by various agencies and industry groups and are very difficult as our overall knowledge of the sun is still rather limited. Many solar scientists would suggest, for example, that we really don’t have a good idea about what happens inside the sun.  It is thought that the solar magnetic field is generated by a dynamo inside the star, a rotating, convecting, and electrically conducting fluid that converts kinetic energy into magnetic energy, spinning a magnetic field out into space around the Sun. Sunspots are thought to be related to the sun’s rotation and the solar equator actually rotates faster than the poles. If straight magnetic field lines running longitudinally were to be dragged along with this rotation, they would become stretched and eventually tangled, generating temporary, localized regions of strong magnetic fields, or sunspots.

Despite our limited knowledge of the sun, predictions are indeed made for solar cycle activity as, for example, they are important for determining the life span of satellites in low-Earth orbit, as the drag on the satellites correlates with the solar cycle. A higher solar maximum decreases satellite life and a lower solar maximum extends satellite life.  Also, the prediction gives a rough idea of the frequency of space weather storms of all types, from radio blackouts to geomagnetic storms to radiation storms, so is used by many industries to gauge the expected impact of space weather in the coming years. The current solar cycle, 25, appears to be more active than the consensus prediction with more sunspot activity at this stage compared to many of the earlier predictions. For the month of August, for example, the sunspot number averaged 75.4 versus a predicted value of 48.4. There certainly is still a chance that solar cycle 25 ends up as another weak cycle with less sunspot activity compared to normal. If so, this would continue a recent trend that has featured weakening solar cycles since cycle 21 peaked around 1980.