Topband: Top-band Prop along grayline?

[KT2Q]

All:

John's post about long-path to Japan on top-band is very interesting. It 
would seem, as John mentioned, to be very rare.

The greatcircle path from W1-to-JA in early January at 2200 UTC falls 
somewhat on the grayline, but much of it is already in sunlight. There would 
seem to be a lot of absorption as well as path skewing due to the gradient 
along the day/night ionosphere.

If the top-band signal skews away from the daylight side of the day/night 
terminator, how can it make it long-path from W1-to-JA if not by the 
greatcircle path? If we forget about the skewing for a moment, the daylight 
path is still severely absorbed as it bounces through the D-region with a 
bunch of lossy E-hops.

I've learned to keep an open mind when it comes to propagation, but how can 
this path work when the "laws" of ionospheric physics say otherwise?

73 Tony KT2Q