[PPRAANet] Current Condx of the Sun

[W0rw@aol.com]

Here is a good explaination of the current solar conditions by
Paul Harden at the VLA.
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Historically, the downside of the solar maximum tends to be the most

violent in terms of sudden major flares and disruptive coronal holes.

Many of the power failures we know about, due to a huge geomagnetic

storm (the famous Toronto and NYC failures), occured on the DOWNSIDE

of the solar cycle (after the maximum, heading towards the minimum).

Some of the largest photographed flares (before the days of satellites)

occured on the downside.  The largest flare ever witnessed, the

"grand daddy" in 1962, was on the downside (that cycle peaked in 1958).

Everyone assumes that once you're past the maximum, the sun goes

dormant.  Not hardly. 


It is not known precisely what causes the approximate 11-year solar

cycle.  The dominant theory is the sun's interior contains these huge

cells of swirling hot gasses.  These cells are sort of like the sections

in an orange, originating near the center and going outward towards the

surface.  In the case of the sun, there are several layers of cells

between the center and the surface.  The large cells just beneath the

sun's surface are called the sub-surface convergence zones.  Hot plasma

gasses rise in these zones towards the surface, where they get slightly

cooled and sink towards the bottom of the zone.  Here, the interior of

the sun heats the gasses back up, they rise to the surface, cool off and

sink again.  It is believed it takes 11 years for this cycle to occur,

and hence the driving force behind the 11-year solar cycle. 


As the hot gasses rise, interactions with the cooler surface causes

strong disturbances, almost like the surface of boiling water, disturbing

the surface. These interactions also produce strong, localized magnetic

fields that leave the sun's surface at one point, and re-enter at another.

Where these magnetic field lines leave and enter, it tends to stablize

the swirling gasses on the surface, allowing the immediate region to

cool down. These cooler "blobs," where the magnetic field lines are, are

called the "sun spots."  If these magnetic field lines grow in intensity

enough, they become strong enough to literally suck the hot gasses from

underneath the surface outward in a small area along the field lines.

This is a solar flare.  Some photos of a flare look more like an

elongate halo or donut.  This is the gasses trapped along the field lines

of the magnetic disturbance.  Of course, such flares hurl gobs of

electrons and sometimes protons at us at nearly the speed of light,

causing momentary disruptions to HF.  The force of the flare also produces

a shock wave, which will hit the earth 40-60 hours later, if the trajectory

between the flare and Earth is correct.  When this shock wave hits the

Earth, it swashes our own magnetic field and triggers a geomagnetic storm

that often lasts for hours. 


But what about the sun AFTER the solar maximum? 


The gasses in the convergence zones are now cooling and sinking towards

the interior of the sun.  The suns surface is slowly cooling down a bit

as these gasses are no longer heating it as before.  The surface of the

sun becomes less violent.  The interactions that produce the magnetic

field lines, and hence the sun spots, becomes more infrequent.  Since

there are numerous of these convergence cells under the suns surface,

all doing their own thing, means the suns surface is NOT cooling down

uniformily.  Some areas remain hotter than others, some areas are cooling

faster than others.  This tends to create areas of stratification, as

the cooler gasses sink, and the hotter gasses rise.  The cooler areas

are more dense and tend to cling together, forming continent size areas

of cooler gasses on the suns surface. However, due to factors, such as

the sun is rotating and hot swirling gasses are applying force to these

huge cooler areas, the cooler areas sometimes tear or rip apart, forming

a large hole.  This is called a "coronal hole."  This hole exposes the

sun's interior to the surface momentarily ... well, for several days

(momentarily in the grand scheme of things I guess).  Out of this hole

pours lots of energetic electrons and hot gasses (gas is heavier matter

compared to electrons).  These things get trapped by the sun's magnetic

and gravitational fields, and ride outward from the sun along with the

solar wind. 


If the escaping mass from a coronal hole is near the center of the sun,

the solar wind will carry it to the Earth.  It does not cause the SPEED

of the solar wind to change, but it does cause the DENSITY of the solar

wind to increase. When the dense particles hit the Earth, it squashes our

magnetic field, just like the shock wave from a solar flare does, to

produce a geomagnetic storm.  The difference is the shock wave (CME) from

a flare tends to be very impulsive, while that of a coronal hole slowly

increases and declines over tens of hours or even days ... keeping our

magnetic field disturbed, and the HF bands in a perpetual state of high

noise, for hours or even days. 


The exception to this is when the Earth ENTERS the stream of particles

from a coronal hole.  The NOAA reports refer to this as "a geomagnetic

storm is possible due to the earth entering a coronal hole stream."  These

particles are blowing out from the sun, just like a stream.  When the

earth passes through a coronal hole stream, the solar wind density can

take a sudden jump, triggering minor to major geomagnetic storms ... just

like a major flare can do. 


So now that we're past the solar maximum, and we all know the solar

mechanisms that produce major flares is dying fast, there are other

physics in motion, namely the coronal holes from the cooling sun, that

still allows the hot gasses from the sun's interior to gush out and

cause harm to the Earth.  Different reasons, but same effect.  Geomagnetic

disturbances that cause huge electrical currents to be generated by the

dynamo effect (our magnetic field moving in respect to our solid core).

These electrical currents cause enhanced noise on HF ... the lower in

frequency you go, the stronger the effect.  It also produces auroras. 


So we're not out of the woods yet.  We will continue to see disturbances

on HF due to solar activity for another year or more yet.  As we near the

solar minimum, we'll see daily solar flux values in the 80's, 70's and

the 60's.  Then ... the sun is legally "the quiet sun."  The higher

frequencies are useless due to an MUF around 12-15 MHz, but the lower

bands 30M and below, will be much quieter then they are now. 


What we are experiencing on the HF bands, following the solar maximum,

is very, very NORMAL.  We simply have to wait it out.  Conditions will get

quieter over this winter. 


But also keep in mind, not all of the noise you hear on 40M at night is

due to the sun.  How many more megawatts of power is being sent along our

electrical power grids today than say 11 years ago?  In North America

alone?  That power is not going from the generating station, along

hundreds of miles of transmission lines, to your PC, microwave oven and

refrigerator with 100% efficiency.  Much of it is being converted into

heat and electromagnetic fields along the transmission lines, generating

radio emissions, thermal emissions (1/f white noise) and impulse emissions

(spark breakdowns across cracks in insulators, etc.).  These are all

generators of noise in the HF bands, and this is increasing year after

year as our electrical consumption increases. 


The next time your town or city experiences a power outage, even if only

for a few minutes, QUICKLY turn on your rig and check the noise level on

40M with the power out, and later when it is restored.  That's happened

to me twice while I was on the air, and the drop in noise level is

instantly noticeable.  You may not see a difference for a localized

power failure (within a mile of your house), but you certainly will at

larger scales. 


This is a growing concern to our HF environment.  We don't need Broadband

crap to trash the HF bands ... increasing power demands over the next

decade, combined with aging electrical distribution systems, will have

the same effect eventually.  BPL will only make it worse, faster. 


Hopefully the above helped explain the "solar physics" behind some of

what we are experiencing.  Inspite of some of the whacko guests and

"remote viewers" on Coast-to-Coast AM that claim this is the most violent

solar activity ever and the sun is going crazy, and even possible it can

soon "blow" and destroy all life on Earth as we know it ... this solar

cycle was actually well below normal, below predictions, and it's really

doing nothing special.  The cruddy, unpredictable bands are the same ole

crap being experienced after a solar maximum since Marconi.  Simply look

at the comparison charts between cycles and see for yourself, such as:

http://www.dxlc.com/solar 


72, Paul NA5N