# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Dip uncertainty
From: Alexandre Eremenko
Date: 2004 Dec 8, 20:30 -0500

```Dear Fred, George and Bruce,
I think that there are three ways to resolve
this question.
1. Mathematically. For this we need some specific typical
temperature-pressure profiles. I volunteer to do the math,
including computation. The question is where to get the
data from. These data were measured millions of times
(for the artillery needs, for example). The question is,
where can WE obtain specific samples from.
I mean just how the temperature and pressure
can vary as a function of
height
for small height, say from 0 to 30 feet over the ocean surface.
2. Experimentally. Well, in my next trip to Norway, I will
take my sextant and will systematically measure the dip of the
horizon from various heights on the shore. (I explained in
one of my previous messages on the subject how to measure the dip
with a sextant, GPS, watch and almanach).
3. Literature search. This I don't know how to do.
I mean I know very well how to do such search in math,
but not in "atmospheric science", "practical astronomy" and such.
Next time I go to Russia/Ukraine I will comb the libraries there
within my reach.

Some Internet search shows that there are papers
trying to find the temperature/pressure profile
FROM the observed refraction:-)
Actually I don't know how to find in practice this temperature/pressure
profile in a given place at a given time.
I suppose in the antiaircraft artillery they launched special
baloons to do this. But this I cannot do:-(

Alex.

On Wed, 8 Dec 2004, Fred Hebard wrote:

> Frank,
>
> It may not be science, but couldn't it resolve this question?
>
> Fred
>

```
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