Category Archives: Ap index

Svensmark Theory—Cosmic Rays Contribute To Lower Global Temperatures

The previous posting closed with: 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 Svensmark theory. This theory begins with high energy galactic cosmic rays (GCR) entering the Earth’s atmosphere where they collide with atmospheric molecules of oxygen. The collisions shatter the molecules and the resulting particles become nuclei for cloud droplets from which clouds are formed. Clouds reflect a significant amount of the Sun’s radiation back into space.  The weaker the Sun’s magnetic field (low solar activity),  the more GCR enter the atmosphere.  The more clouds, the more cooling.   This is opposed to the situation where the Sun’s activity is high, fewer GCR result in fewer clouds.

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Solar Cycle 24 July Update

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.


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Solar Cycle 24 March Update

There was a small upward spike in Sunspot numbers in March.   Dean Pesnell of NASA’s Goddard Space Flight Center thinks this will make Cycle 24 a double peak “maximum” event.  He says that the second peak may even last into 2014.
(Click on the Charts for more Clarity)

NASA Revises Cycle 24 Sunspot Prediction.

David Hathaway, NASA solar cycle expert, has a revised forecast for Solar Cycle 24 Sunspot number and Maximum timing.  In May 2012, he forecast the smoothed sunspot number maximum at 60 and the timing of the maximum as the spring of 2013.  His January 2013 Cycle 24  revised forecast is for 69 spots and maximum in the Fall of 2013.  He adds:
“ We are currently over four years into Cycle 24. The current predicted and observed size makes this the smallest sunspot cycle since Cycle 14 which had a maximum of 64.2 in February of 1906.”  
       Hathaway’s  NASA Revised January 2013 Sunspot Number Prediction

Solar Cycle 24 Nearing Maximum

Solar Cycle 24 is nearing its maximum after which the solar activity will decline.     The maximum is often pegged as the time when the Sun’s  north and south poles swap. The chart below shows the current position of the poles. Projecting their current position suggests that the swap will occur early next year.
(Click on Charts to improve clarity)
    Solar Polar Field 1966 to Present –Wilcox Solar Observatory

NASA’s Stereo Mission Captures CME–Fastest Ever Recorded

On 23 July 2012, NASA’s Stereo **Mission spacecraft recorded a coronal mass ejection (CME).   The cloud of solar material ejected from the Sun sped out into space at a speed of “between 1,800 and 2,000 miles per second”.  That translates to about 7.2 million miles per hour or about 1.1% of the speed of light.  NASA says it is probably the fastest CME ever measured by any spacecraft.  Incredibly,  it is said that, on average,  the mass ejected into space is  1.6×1012kg.   A video of the  23 July CME can be seen by clicking here.

From the NASA announcement of this event:

“Measuring a CME at this speed, traveling in a direction safely away from Earth, represents a fantastic opportunity for researchers studying the sun’s effects. Rebekah Evans is a space scientist working at Goddard’s Space Weather Lab, which works to improve models that could some day be used to improve predictions of space weather and its effects. She says that the team categorizes CMEs for their research in terms of their speed, with the fastest ones – such as this one — labeled “ER” for Extremely Rare.”

**The STEREO mission consists of two spacecraft with orbits that for most of their journey give them views of the sun that cannot be had from Earth. Watching the sun from all sides helps improve our understanding of how events around the sun are connected, as well as gives us glimpses of activity we might not otherwise see.


Solar Cycle 24 Update July 2012

Solar Cycle24 July sunspot and F 10.7cm radio flux numbers are up slightly from June.  Pretty much in line with the activity projection and much below that of Solar Cycle 23. (Click on Graphs for Clarity)

Large Filament on the Sun

The Sun currently has a filament that stretches more that 400,000km across the face. Filaments are formed in magnetic loops that hold relatively cool, dense gas suspended above the surface of the Sun. Because they are cooler than the photosphere they can look dark.

courtesy of

But when viewed in profile they look like a giant loop, called a prominence.

courtesy of NASA

Occasionally when these filaments collapse,  a coronal mass ejection (CME) can occur.   Because the filament is looking directly at the Earth,  a CME could cause problems.   Lets hope this does not happen.