Posted by nicksanspam on July 9, 2007, 12:17 pm
>... Refraction shifts the apparent position of the sun upward by about
>half a degree when it's close to the horizon
I seem to recall that "line-of-sight" radio waves propagate as if
the earth's diameter were 5/4 larger, owing to the atmosphere...
Nick
Posted by nicksanspam on July 9, 2007, 7:22 pm
>-> I seem to recall that "line-of-sight" radio waves propagate as if
>-> the earth's diameter were 5/4 larger, owing to the atmosphere...
IIRC, it depends on the density of the atmosphere, to the extent that
a person might be able to see the back of his head on venus, if there
were no scattering or attenuation.
>Refraction of light (and other electromagnetic waves) is much more
>significant than is often thought. I live very close to the northern
>shore of Lake Ontario. Geometrically, it should be impossible for
>someone standing close to the water to see across to the other side...
One sailing rule of thumb is that the distance to the horizon in nautical
miles is roughly the square root of the observer's height in feet.
Nick
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>half a degree when it's close to the horizon