On Sat, 04 Oct 2003 18:06:23 -0700, Roy Lewallen
wrote:

At 60 kHz, there shouldn't be any difference between daytime and
nighttime propagation. Certainly the ionosphere isn't involved.

Roy Lewallen, W7EL

Don't forget the daytime LF/MF attenuation in the D-layer, by
preventing it from reaching the E-layer, which sets the LUF (Lowest
Usable Frequency). At night, the D-layer disappears, thus, the signal
can reflect from the E or F layer.

At least the 77,5 kHz Maiflingen standard time transmitter in Germany
is usable to about 2000 .. 2500 km from the transmitter during the
night at least in the winter. However, during the summer nights, the D
layer is in constant sunlight all night nearly 1000 km south of the
arctic circle, which may explain the worse conditions during summer
night, but of course the number of lightnings is also higher during
the summer, increasing the band noise.

Paul OH3LWR