For anybody interested in amateur radio or short wave
radio listening, Solar activity is finally starting to pick up
as the belated Solar Cycle appears to be finally occurring.
This is supposed to be a roughly 22-year cycle in which
the Sun begins to show spots on its surface. The spots show up
every eleven or twelve years but reverse magnetic polarity each
time so the whole cycle is thought to be about 22 years long.
During a peak in Solar activity one sees lots of spots
in a view of the Sun and these spots represent upheaval of the
Sun's surface. They spew jets of hot gas and subatomic particles
in to space and they also effect the Earth's magnetic field
causing rather interesting effects in short wave radio
communications and sometimes even effecting long power lines and
telephone cables.
For amateur radio operators, the increased Solar
activity causes certain amateur radio bands that normally only
let you communicate to roughly the horizon to talk around the
world.
The same Solar disturbances also take away good
reception in the form of radio blackouts in which normal
communication paths stop working for a few minutes or even a day
or so in the case of a really big blackout.
In the fifties, there was a fabulous Solar cycle around
1958 that some really old-timers still talk about today. I was
alive then, but too young to get in on the fun for that cycle.
The first one I remember was around 1970 and it was a
dandy, also. At that time, the BBC and the ORTF in France still
operated television in the so-called Band-1 TV band and you
could listen to British and French TV sound between 41 and 42
MHZ.
The Solar cycle around 1978 or so was also very good as
was the early nineties and the time around 2000.
The amount of Solar activity is expressed in the amount
of radio static received from the Sun at around 2.7 GHZ each
day. It is given a number and those numbers are finally
climbing.
A couple of years ago, Solar Flux numbers were in the
mid sixties. Now, they have recently come up to as high as 190
last weekend and are now around 130.
If you like this kind of stuff, it is starting to happen
again so, if you can, enjoy. One place to get the daily Solar
Flux numbers is
http://www.swpc.noaa.gov/ftpdir/latest/wwv.txt
If you wonder how Solar activity can effect a power line
on Earth, it works like this.
Any time you sweep a piece of wire through a magnetic
field, an electric current can be measured in the wire. That is
how a generator works and that is how the dynamic microphone in
an audio recorder or telephone hand set also works.
The magnetic field of the Sun interacts with that of the
Earth and actually makes the magnetism detected in one spot
appear to change slightly. If there are miles of wire, that wire
unwittingly becomes a sort of generator and feeds low-frequency
waves of current in to whatever it is connected to. If the field
is varying enough, it blows fuses or circuit breakers or puts
static on to telephone lines. It also causes pipelines to be
damaged by inducing electrical currents in to the pipe and
causing the metal to actually leave the pipe and go in to the
ground around it.
This present Solar cycle is slow to get going and
experts say it may sort of fizzle and not do much, but there is
no way to know for sure so enjoy it while you can. It is
expected to peak around 2013.
Martin
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