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Gary,

thanks for the pages on refraction. My comments on refraction on the
horizon were just muddled thinking - of course the sky itself is a
long way away and is therefore refracted, but the sea which determines
the line of the horizon is only a few miles away and therefore doesn't
have as far to suffer.

However, as I've often seen a distortion of the sun as it goes beneath
the horizon I think this is evidence for some kind of affect that
distorts light at the horizon, which because it happens near the
horizon must be due to some kind of affect that bends light close to
the ground and surely this "heat haze" must have a significant impact
on the position of the horizon?

Perhaps a warm sea/cold air is an unlikely observation event (its
called fog), but a cold sea with warm dry air coming over it must have
some kind of affect which will alter the observed position of the
horizon - or does it?

Mike

On Nov 20, 7:04 pm, Gary LaPook  wrote:
> Gary LaPook writes:
>
> Attached is an excerpt from Dutton, explaining refraction, and the
> sextant correction table from the 1999 Nautical Almanac to assist Mike
> Lenzie. The sun correction table includes refraction and semi diameter
> for upper and lower limb observations. The included dip table is for
> correction of height of eye above sea level and can be computed from the
> formula:  dip (in minutes of arc) = .97 times the squaare root of the
> height of eye (in feet.)
>
>  Dutton 1934 refraction.pdf
> 97KDownload
>
>  refraction, N.A. 1999.pdf
> 53KDownload
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