I posted Solar Cycle 24- A Game Changer? which discussed the weak cycle 24 and what it might mean in terms of a cooler global climate. As the posting was getting quite long, I elected to leave out the Butterfly Diagram for later posting. So, now is later.
This figure is sometimes known as the Maunder Butterfly Chart as Maunder seems to be the first person to recognize the unique pattern formed by plotting the position of the sunspots on the face of the sun versus time. When a new solar cycle begins, the sunspots become numerous. In the beginning they appear away from the equator at about 35 degrees south and 35 degrees north. With time the spots begin to converge at the equator. When the “minimum” occurs, the spots are basically upon the equator.
The butterfly chart for Cycle 24 is perhaps showing sunspot formations that are relatively fewer than in recent Cycles 22 and 23. Cycle 24 seems to resemble cycles that occurred many years ago. If you occasionally check the progress of the spots toward the equator, you might be able to make a good guess on the length of Cycle 24. Will it be much less than the average of 11 years? The experts probably have a better feel than we amateurs, but I am pretty sure that they would not bet the farm on their feel.
There is an interesting paper “First Solar Butterfly Diagram from Schwabe’s Observations 1825 1867” by Rainer Arlt and Anastasia Abdolvand, This paper uses the spots recorded by Schwabe during the named period to assemble butterfly diagrams for Cycles 7, 8 , 9 and 10. These are the butterfly diagrams that immediately precede those in my first chart. Cycle 8 was a weak cycle according to the authors.