At 07:13 PM 10/19/2005, Charles Bibb wrote:
>Has anyone else considered that if propagation conditions on topband are
>indeed enhanced by a full moon or a harvest moon that the effect might have
>more to do with tidal effects on the ionosphere than any sort of
>electromagnetic reflectivity of the moon's surface?
>
>If the moon can induce changes in costal sea-level amounting to dozens of
>feet, then what effects could it exert on a much lighter (less dense)
>medium, and one that is far less constrained (near-zero gravity) by Earth's
>gravity?
>
>Such "ionospheric tides" could elongate, distort, tilt, perturb, etc. the
>radio-reflective layers of our atmosphere in ways we have not yet
>discovered, possibly leading to the propagation enhancements that some
>claim to observe.
>
>Something to think about (and research),
>
>Charles - K5ZK
I'd just quibble with you on your assertion of "near-zero"
gravity. Not true at
all. Astronauts are "weightless" because they are falling with an
acceleration
equal to the acceleration of gravity. This angular acceleration is
due to the orbital
velocity of about 17,000 miles per hour in low-earth orbit. Clearly
gravity extends
for very long distances. One measure of this is the fact that we
have a MOON out
there to discuss in this context. A moon held captive by earth's gravity.
There are many effects on the structure of the upper atmosphere, such
as tidal effects
--both directly from the moon and the fact that the atmosphere sits
on the ocean and
the ocean tides can be propagated upwards. Even things like
underground nuclear
tests have caused enough surface variation to have atmospheric waves propagated
globally. And sprites (upwards lightning into the upper atmosphere)
can couple
acoustic energy (thunder) into the ionosphere.
There are reasons that the tropopause and stratopause make it more
difficult to transfer
energy upwards from the surface, but it can be done. So there are a
lot of possible
surface events that MIGHT be able to influence 160M propagation
during periods of
higher tides, in addition to events generated in the atmosphere
itself. The real issue
is to sort out which events actually have the energy to make a
significant difference
(if at all).
--John W0UN
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