I decided to make an animated GIF of the latest cycle 24 sunspot, dubbed number 1002, which was literally a “flash in the pan”.
Credit: SOHO/MDI
One thing that has been common so far with all cycle 24 sunspots this year is that they have been small and very short lived. This one lived just slightly more than a whole day, a mere blip in solar time, where some sunspots will survive for a whole solar rotation (27 days) or more.
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Chris Knight wrote on the Earth and its sustaining of geomagnetism
Another view
There is huge amount of iron in the Earth’s crust which has permanent magnetism frozen in. Looking from a purely engineering point of view, if there is a rotating conducting sphere (regardless of its temperature and composition) within the crust, then electric current will be induced in the sphere. The requirement is that inner sphere rotates at slightly different speed to the crust which is not implausible considering existence of a viscous layer. The induced current then via its own magnetic filed would over time strengthen permanent ferromagnetic field in the crust.
Polarity of induced current (and of the resultant magnetic field) will depend on which one rotates (even slightly) faster; the crust or the core. If there is no difference then the induced current (and the resultant magnetic field) will drop to zero.
Now imagine an asteroid approaching the Earth at an oblique angle following its orbit; the time (day or night) at the place of impact will determine whether the crust will speed up or slow down in relation to the core. Considering that they are separated with a viscous layer an impact will have greater effect on the crust then the core (the core is higher density; gyroscope effect). After few thousands millennia the speed difference will drop to zero. In meanwhile another asteroid may hit the Earth again; if speed difference is sufficiently low and this time happen to be day instead of night at the place of impact, newly arising speed differential will be of opposite sign so it would be polarity of induced current and polarity of the Earth’s magnetic field will flip.
To prove validity of the above it would be necessary to compare geomagnetic records with records of species extinction and sudden climate changes. Only alternative day-night time impacts (if asteroids hit only following the Earth’s orbit) would cause reversals and only if the speed differential is very low or zero.
From Lief: About the UV: the Far Ultraviolet that varies significantly with the solar cycle does not penetrate. We do get some of the less energetic UV [just below the visible], but the flux of these vary oppositely to solar activity [i.e. goes up when solar activity goes down].
As the links that you provided attest to, the Near UV (the last 1/3 of it) is up compared to the rest of the spectrum. I have wondered somewhat that as soon as you get to the next sensor (the visible) the lowest values are again back down. Is there something in the detectors that is causing the sharp drop? i.e. – the NUV imaging chip might have a propensity to become overly sensitive near the end of it’s ramge, or the filter for the visible range is cutting off the violet sensitivity too early.
Robert Bateman (20:19:44) :
As the links that you provided attest to, the Near UV (the last 1/3 of it) is up compared to the rest of the spectrum. I have wondered somewhat that as soon as you get to the next sensor (the visible) the lowest values are again back down. Is there something in the detectors that is causing the sharp drop?
No, it is not the sensors, but the Sun. It doesn’t matter though: the UV that causes sunburn and are dangerous are at and lower than 300 nm and are thus inside the band 240-310 that shows the negative correlation with the sunspot number.
The question that has been bugging me for many months, Lief, is that if the NUV in the dangerous range is up, is it getting through to the surface, where us humans live?
i.e. – Should the public be warned?
I believe members of Congress have been warned, as Sen. McCain dropped a hint about the Sun a couple months ago.
Robert Bateman (10:19:46) :
Should the public be warned?
I do’t think so. The change is very small, and happens in every solar cycle [as far as we know].
Please bear with me (I know I am a pain at times, my apologies in advance):
Are we absolutely certain that the change is ‘normal’ and is well within that which is to be expected at Solar Minimum?
Robert Bateman (18:42:17) :
Please bear with me (I know I am a pain at times, my apologies in advance):
Are we absolutely certain that the change is ‘normal’ and is well within that which is to be expected at Solar Minimum?
You are never a pain, and one is ‘never’ absolutely sure of anything, but I’m sure enough that I’ll not consider any other interpretation. This is normal.
Well, ‘normal’ for the long term, in the sense that nothing terrifyingly new is likely to happen, but this cycle transition has been somewhat ‘subnormal’ in a number of measures, and often just barely so, too. F’rinstance, the magnetism measured by Ulysses; f’rother instance, the number of spotless days. Ignorant of ‘normality’ we be.
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kim (06:09:51) :
F’rinstance, the magnetism measured by Ulysses
The claim by NASA that there is a significant drop in the Interplanetary Magnetic Field from the last minimum to this minimum is a blatant PR-stunt. Ulysses went over the poles in 1994-1995 and then again in 2007-2008. The first time was two years before solar minimum while this time we are much closer, perhaps even at solar minimum. The decrease in the magnetic field between the two Ulysses passes is just the normal decrease during the declining phase of the solar cycle. What they claim is like saying that the Earth is cooling because the temperature in Houston has decreased 40 degrees from July 2007 to January 2008.
Leif (11:42:57) Well, thanks for the correction. One thing I like about this exchange is how readily I can display vast ignorance. Well, let’s take Livingston’s measurements as another f’rinstance, then.
I maintain, from little actual knowledge, that what the sun is doing now is unusual, not so much abnormal, as irregular, or at the very least, not within a regularity understood by us as yet.
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kim….maybe we are not looking back far enough…all the science is really the last 50 yrs or so. This situation of sol is not unusual, just not observed in our lifetime.
Re: UV and TSI. The SORCE data sheet indicate that sigma for the UV sensor is 12-24% corresponding to the occasional 100% variance in UV.
In practice, this situation is a challenge for the engineer.
1. A transducer cannot, as a rule be both, sensitive and invulnerable.
2. Analog data that can fluctuate wildly or chaotically (repetitively swinging) has to be damped, inorder that the value settle. Since the higher intensities are temporally brief, the optimization here in UV measurment is at lower, steady-state, energies.
Of the total TSI 40% is IR, of which total only 1% reaches the ground. 40% is in the visible spectrum, subject to reflection with increasing albedo. 20%, nominally, is UV, but the measure of this spectrum is less well taken.
Gary Gulrud (09:02:03) :
Re: UV and TSI. The SORCE data sheet indicate that sigma for the UV sensor is 12-24% corresponding to the occasional 100% variance in UV.
I think that it pays to be a bit more precise. The ‘variance’ is normally the square of ‘sigma’, so the numbers don’t come out right. And percentages are a poor way of characterizing some that varies a lot. E.g. what is the percentage change of the sunspot number from minimum to maximum?
Maybe by ‘variance’ you meant ‘variability’? but, if so, measured how?
I bow, ‘variablility’. I will review my terminology.