I hope this is the correct newsgroup for this question.
Can someone explain DX Ducting?
I believe thats the correct word.

I live in a rural area, and my nearest tv stations are about 50 miles
away. Those 3 stations normally come in pretty good. (one VHF, two
UHF) I have a 7 element antenna pointed approx. north (toward that
city). The other closer stations are to the south, and are 65 and 90
miles away. They dont come in as good, but are usually viewable.
Turning the antenna South helps those, but I have to do it manually
until I get a new rotor. (old one died).

For some reason, starting on Saturday, I have been getting tv stations
from up to 275 miles away, yet I can not get any of these "local"
stations at all. What's really weird, is that the stations I am
getting are all to the East of me. In other words, they are broadside
to the antenna. I have never heard of getting a signal on the
broadside.....

Just for grins, I called the 800 number of one of these distant
stations, and they were happy to hear they were transmitting about 250
miles. They said the reason is called ductingm and said it's caused
by the atmosphere and weather conditions.

OK, I can undestand this (sort of). I do recall back in the 70's when
I had a CB radio in my car, and getting "Skip". But this TV things is
different, becasue a tv antenna is directional, unlike a CB antenna
that tends to transmit in all directions.

I looked up "Ducting" on the web. Most were about heating ducts, but
did find one link which was way over my head. I'd have to be an
engineer to understand it.

In simple terms, could someone please explain this. Particularly why
I can not get the "local" stations, and how can I get very distant
signals on the broadside of my antenna?

Thanks

Mark