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HIAWATHA VALLEY 10-X CHAPTER
SUN. 2000 local 28.750 MHz
READINGS FOR FEBRUARY
High | Low | Average | |
Solar Flux | 93 | 73 | 83 |
A-Index | 19 | 2 | 9.3 |
At the time of this writing it looks like
I was right about the March A-Index, but
too high on the solar flux. But March 10-
17 has had above average conditions, as
predicted: March 12-13 has been the best.
so far with all night 10 meter openings.
April forecast: Solar flux 78. A - Index
8.4.
Cycle 21 will be either super high or very
low. Current theories place the sunspot
number ( ssn ) at either a low 50 or super
high of 200. But sunspots are only indi-
cators of solar activity. The true factor
that affects radio propagation is the
amount of Ultraviolet Radiation that goes
through the Earth's ionosphere (EUV) . This
is why the winter months are better for
DX than are summer months. In the winter
the sun is at a low angle to the Northern
Hemisphere, forcing the EUV to travel
through more of the ionosphere.
It has been proven that cycles with low
SSN have a higher EUV. To illustrate this
let's take an example. In cycle 17, a SSN
of 110 had a critical frequency of 13MHz.
In cycle 18, a higher cycle, a SSN of 130
was needed for a critical frequency of
13MHz. The reason for this is that cycle
17 had more EUV per sunspot than did cycle
18. But despite this, it turns out that a
high cycle is usually the best.
Fig. 1 shows solar activity over the last
few centuries, using C14, auroral, and
actual measurements as sources for the
data. As we can see from the diagram, the
sun is very unstable, with periods of high
and low activity. Ever present though,
are the solar tides, but the sun does not
always respond to the tides. Currently we
are in a period where the sun is respon-
ding. By using the 179 year cycle of
cycles, we see that the sun is becoming
more responsive to the tides as time goes
on. An example is the 179 peak of 155 as
compared to the 1958 peak of 200, 179years
later.
By using the 179 years cycle-method, cycle
21 should be at least as high as cycle 5
which had a peak of 50. My personal pre-
diction for cycle 21 is an SSN of about
100, producing conditions about the same
as 1968.
You the reader may now ask,"what about the
1982 alignment of the planets? " Well, in
1982 the planets will be in alignment on
one side of the sun. Now if half would be
on one side, and the other half on the
other side, the tides would be much
stronger and super conditions would pre-
vail (1958?).
Where does the energy for sunspots come
from?
It had recently been observed that during
periods of sunspot minimum, the suns outer
shell spins at a faster rate. During sun-
spot maximum the shell slows down. It is
thought the speed built up may build up
the energy to be taken out at the next
sunspot peak.
If you have questions about 10 meters or
would like to see some other topic covered
in my article, drop me a line or check
into the chapter net.
2. Solar Tides: See HAMGRAM, March 1977.
1. Critical Frequency: The frequency at
which a radio signal radiated at 90 deg-
rees will return to the Earth.