A graphical comparison of solar cycles 21, 22, 23 and 24

Solar cycle 24 has initially displayed much less activity than recent cycles. Based on statistical models the monthly smoothed sunspot number is likely to peak between 50 and 70 in 2013. Models based on solar polar magnetic field strength indicate the peak could occur as early as in 2012. The comparison with recent cycles is interesting to track the development of cycle 24.  The X axis in the chart is the number of months since the cycle started, while the Y axis is the monthly smoothed sunspot number.

Chart color overview

Cycle Monthly smoothed sunspot number

  • 21 Blue
  • 22 Black
  • 23 Red
  • 24 Violet


  • Cycle 21 started in June 1976 and lasted 10 years and 3 months.
  • Cycle 22 started in September 1986 and lasted 9 years and 8 months.
  • Cycle 23 started in May 1996 and lasted 12 years and 6 months.
  • Cycle 24 started in December 2008.

Please note that the start dates for each cycle is calculated using the 13-month smoothed monthly mean sunspot number. One advantage of using this statistical (numerical) approach is that the start month of a solar cycle is the same as the month of the solar minimum. It is possible to use other criteria to separate solar minimum and the start of a solar sunspot cycle, however, which criteria to use and how much importance each is given, unfortunately leaves room for individual opinion.

via A graphical comparison of solar cycles 21, 22, 23 and 24.


5 thoughts on “A graphical comparison of solar cycles 21, 22, 23 and 24

  1. Otter February 23, 2013 / 4:29 pm

    I notice the double peak in cycle 23, seems to be foreshadowed in cycle 22. I’d be curious to see if an even more pronounced double peak would occur in cycle 24…

    • Juergen Uhlemann February 26, 2013 / 1:53 pm

      Thanks Sean for the link and it contains a link to “Sun Oddly Quiet—Hints at Next ‘Little Ice Age?'” http://news.nationalgeographic.com/news/2009/05/090504-sun-global-cooling.html

      I was amazed to read what Mike Lockwood, a solar terrestrial physicist at the University of Southampton in the U.K said.
      “I think you have to bear in mind that the CO2 is a good 50 to 60 percent higher than normal, whereas the decline in solar output is a few hundredths of one percent down,” Lockwood said. “I think that helps keep it in perspective.”

      Lockwood considers the whole sun output (100%) and then compares to the CO2 that is only about 390ppm of the atmosphere. Actually, he is refering to “50 to 60 percent higher”, which is roughly 140ppm increase based on about 240ppm.
      I don’t know where he studied math, but my math tells me that 0.039% of the atmosphere (CO2) would effect the sun input and the other 99.961% (simplified by ignoring clouds, etc) would not effect the sun input.
      If the sun would change by 1%, which would be a lot, then the CO2 itself would effect 0.00039% of that change. In other words, 99.00061% of the sun change would not be effected by the CO2.
      I got the energy output of Sun from http://www.physicsforums.com/showthread.php?t=223449 and it has the estimate of 3.846 × 10^26 watts, or 3.846 × 10^33 ergs/sec.
      This output is required to have create our climate on earth. How much change of that output would make a noticeable change on earth?
      What’s about Lockwood’s “solar output is a few hundredths of one percent down”
      0.0001% = 3.846 10*22 watt and then a few of that.

      I compare it with a pond and a marble. If I drop 1 marble (CO2) into the pond and then drop 100% more CO2 = 1 marble into the pond, how much did I change?

      Is “Climate Science” actually science? After watching “Feynman on Scientific Method” http://www.youtube.com/watch?v=EYPapE-3FRw#! , it makes you wonder.

      No proof for CO2 impact. Only models. Now “IPCC Railroad engineer Pachauri acknowledges ‘No warming for 17 years’” http://wattsupwiththat.com/2013/02/22/ipcc-railroad-engineer-pachauri-acknowledges-no-warming-for-17-years/

      • Tony Lawton June 29, 2016 / 3:02 pm

        CO2 has a geometric relationship with concentration inverted.
        IE The first 100ppm have its max effect as a ‘greenhouse’ gas at that concentration plants are struggling.
        Over geological time no relationship between CO2 and temp.
        Climate drivers are
        Orbital – Milanokovich
        Water vapour acts as a negative feedback (latent heat evaporation) to global warming.

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