[EMAIL PROTECTED] wrote:
But it still dosnt explain the great prop without sun spots. Anyone
have any ideas?
Frank,
The sun still puts out some solar flux even without visible sunspots. Solar
flux rises and falls with visible sunspots over the 11-year cycle, but it's
the solar flux that is actually responsible for charging the F layer, and
there's always some of that coming our way, even during the solar minimum.
The other factor is absorption. High numbers of sunspots and the associated
high solar flux level increase the efficiency of the ionosphere, but the
increased solar activity associated with high sunspots (like solar
flares/storms, CMEs, etc.) also causes disturbances in the Earth's geomagnetic
field. Such disturbances absorb radio signals, making ionospheric propagation
very unstable or completely unuseable. Absorption tends to be a bigger problem
in the lower HF region (80M, 40M, 20M) than in the higher HF region (15M,
10M). On the 20M band, therefore, weak signals can be heard more reliably when
absorption is low, even when propagational efficiency is also fairly low.
Of course, this doesn't mean that we don't love those sunspots! :-) But it's
a double-edged sword to be sure.
Bill / W5WVO
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