The sunspot cycle

Sunspots are the result of magnetic flows through the sun.   Although sunspots themselves produce only minor effects on solar emissions, the magnetic activity that accompanies the sunspots can produce dramatic changes in the ultraviolet and soft x-ray emission levels. These changes over the solar cycle have important consequences for the Earth’s upper atmosphere.

There is an approximately eleven year sunspot cycle which has been observed since the early 1600’s.  The monthly daily average of sunspots typically increases from almost zero to over 100 and then decreases to near zero as the next cycle begins. 

Here is a graph copied from About 400 years of sunspot cycles

sunspots_400_years (1)

Note the so-called “Maunder Minimum” which occurred during the “Little Ice Age”, lasting until about 1750, then the “Dalton Minimum” around early 1800, then the spike at around 1830.  Around 1850, global warming occurred.  An expanded graph of the last 250 years, from the same source, shows the modern maximum that occurred near 1950.


We are currently about 2.5 years into cycle 24, and the minimum counts for cycle 23 were extremely low.  Cycle 24 is predicted to be very small in magnitude, and has started out that way.  Some scientists say this predicts considerable cooling.   Here, from the NASA solar science website, is a chart showing their predicted cycle 24:


Cycle 25 is predicted to be even smaller – some scientists believe we are entering a new sunspot regime, like the Dalton or Maunder Minimums.  This would indicate a quiet sun, with low magnetic activity and reduced solar flux.

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