There appear to be different propagation patterns during various sunspot
cycles.
From my article in CQ Magazine June 1980:
http://www.k3bu.us/propagation.htm
It is known that with increased sunspot activity the thickness of the
atmosphere increases. (This caused Skylab to come down prematurely).
This also increases the height of the propagating layers and
therefore increases the height and length of the "arches", it allows
us to span longer distances and extends propagation later into the
night.
We have been told that during peaks of solar activity the lower
frequency bands are very poor, mainly because of attenuation of the D
layer of the ionosphere. On the contrary, the propagation on the low
bands has been better than what we experienced during the sunspot
minima. The 40m. band has longer openings to remote areas of the world.
Eighty meters is the same; we are hearing Europeans around 6 p.m. local
time. During the 160m. CQ Contest I was hearing G stations for about 8
hours during the night. It appears again that the refracting layers are
higher, allowing us to work longer distances with stronger signal
levels.
It appears then that with higher sunspot activity, the average height
of the media increases, refraction of higher frequencies improves,
allowing us to work further and increase the number of useful
frequencies for communication.
<
Area under sunspot cycle count curve would be representative of the
amount of Sun's energy emission over the cycle. Cycles with high
activity would have "fatter" curve, representing more intense energy
hitting the Earth, atmosphere and ionosphere heights increase,
(atmosphere gases expand) and propagation layers increase height. The
result is that sunspot minima between "fat" more intense cycles are
different, they are shorter and with layers at higher altitudes. Minima
between or after low cycles are longer and layers are at lower heights,
changing propagation paths, shorter openings.
There is also hysteresis - flywheel effect where the effects are
shifted, delayed as we see in shift in Earth temperatures (coldest days
are not the shortest days, but shifted.)
To summarize, it appears that best top band propagation happens during
sunspot minima at high sunspot activity cycles. Other variables, layers,
absorption, Earth angles make top band propagation so unpredictable, but
there is a pattern to it. "You gotta be there when it happens!"
This has effect on weather patterns too, where low sunspot cycles cause
atmosphere (gas) to shrink, becomes more dense and weather patterns
change, hurricanes, tornadoes etc. Global whatever, not our SUVs.
I hope K9LA gives me credit for this explanation and record, unlike
denying my pointing out high angle propagation on top band.
73
Yuri Blanarovich, VE3BMV, K3BU.us
topbanding since 1958
On Sun, Jun 05, 2016 at 07:21 PM, John Kaufmann wrote:
> (Note: disregard my earlier incomplete post)
Carl K9LA: " But in my opinion (and in the opinion of others) the
deep and
long solar minimum between Cycles 23 and 24 (2006-2010) didn't live up
to
this axiom compared to the not-so-deep and not-so-long solar minimum
between
Cycles 22 and 23 (1995-1997). It suggests that all solar minimums
aren't the
same."
I will continue the comparison by saying that the solar minimum in the
mid-1980's topped that of the following two decades in terms of low
band
propagation. Top Band activity in the 1980's was nothing like it is
today,
but despite that I observed many openings into Europe that sounded
like a
20m opening. Propagation to mid-eastern and central Asia occurred
pretty
regularly. I remember hearing 9M2AX on long path much louder than
most of
the Europeans he was working. JA's were almost a daily occurrence
into W1
during January of 1987.
I assumed that this was normal propagation for 160 but I have never
observed
anything consistently as good as it was in the 1980's. Anyone else
found
this to be true? What was different about the solar minimum in that
decade?
73, John W1FV
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