NASA predicts a solar magnetic field reversal in about 3 to 4 months. When that happens, Solar Cycle 24 will have reached what is known as the cycle maximum. After that the Sunspot numbers will decrease with time. There is a possibility that a short period of none at all will happen before Cycle 25 kicks in. NASA has produced a video that discusses the mechanism and the implications of the solar magnetic field reversal. The video can be viewed by clicking here.
The July charts for Sunspots and F10.7 cm Radio flux are shown below.
The Sunspots number rose slightly in July. While Sunspots will still appear on the Sun’s surface after poles reverse, the frequency will decrease.
Historically it is well to remember that the time between Cycle 23 and Cycle 24 was one of long periods of time without sunspots. The chart below shows that 2008 was a very unusual year with many periods of no Sunspots. And this trend continued in 2009. And the ensuing Cycle 24 has been the least active since the beginning of the 20th century.
Besides Sunspots, another indicator of the Sun’s activity is the F10.7 cm flux. Compare Cycle 24 shown preceding Cycle 23 on the following chart.
Low Sunspot numbers and low F 10.7 indicate low solar activity. How this activity translates to cooler weather is not clear. The correlation between low activity and cooler weather has been know for several hundred year (or perhaps longer— recently read that the Chinese recorded Sunspot numbers many century’s ago and reported this correlation.)
One possible explanation is the Svenmark theory. We will review that theory in the next posting.