"Martin Rowley" m wrote
in message

Greater than a certain angle with the earth's surface and the
elecro-magnetic (em) energy is attenuated so much that no detectable
signal (on the ground) is found, no matter how much 'bending' occurs.
Less than a critical angle, and the em energy bends sufficiently to be
found up to approximately one-third greater distance than the
theoretical visual horizon.

I suppose I'll have to take a look at it in a little more detail. I
can't see it being much use to me but it is there. Rather like the idea
that a body moving through space will create Rontgen waves if it moves
into a stellar wind.

That may one day prove to be good news for environmentalists but I don't
think anyone is ready for that yet.

I believe the idea of 'one-third' was originally an empirical finding
dating back to the earliest days of wireless transmissions. Of course,
variations in temperature and humidity (particularly the latter) alter
the profile of air density, and lead to super- and sub-refraction and
the special case of ducting - which is the subject of the FAQ entry.

So that so far as you know it is a coincidental ratio. Just me looking
for patterns that may not be there.

I look at things like this wondering "If God made them, why would he
make them "just so"?" and usually finding a stage of ingenuity that
beggars disbelief.



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