Topband: sunset enhancements

[Carl K9LA]

> why aren't there more sunset enhancements?


If the theory is correct that sunrise enhancements are tied to the tilt 
in the ionosphere at sunrise, then one would expect sunset enhancements 
to be just as prevalent since there's a tilt then, too. But there is a 
difference in the sunrise tilt and sunset tilt - the tilt (i.e., the 
electron density gradient) at sunset is not as steep as the gradient at 
sunrise because the recombination process at F region altitudes is 
slower than the ionization process. To reiterate, all of this is not 
proven - it's just the most plausible explanation we have at the moment.

And John K9UWA commented in a personal e-mail that at sunrise the noise 
from the east drops off, too. That's just another effect of propagation 
on the low bands at sunrise that others have mentioned previously.

Carl K9LA