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Re: dip angle refraction correction
From: John Huth
Date: 2011 Dec 2, 17:48 -0500
http://mintaka.sdsu.edu/GF/explain/atmos_refr/altitudes.html
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Keeping up with the grind
From: John Huth
Date: 2011 Dec 2, 17:48 -0500
Nevermind - answered my own question - great website and I should've known because others had pointed this out to me before.
On Fri, Dec 2, 2011 at 5:35 PM, Apache Runner <apacherunner@gmail.com> wrote:
I have a somewhat esoteric question, but I thought I'd pose it to the list to see if anyone knew of a program or website that could do this.Here's the situation - some students are doing a final project where they went to the tallest building in Boston and used a water level to establish a horizontal and then sighted down to the horizon. They then had measurements of the height of the building and want to turn this into a curvature of the earth.They'd like to improve on things and correct for refraction. I don't know of any ready made formulas for correcting for the shift in the position of the horizon due to refraction, since you'd need some model of temperatures etc.I suggested that they could make a 'model' atmosphere that had maybe 4 layers from the surface to the top of the building and then assume either a uniform temperature or a mild uniform gradient and then just do the ray tracing. I'd imagine this is a bit of pain, but not outside of their capabilities.On a related note, since I talked about this effect, they keep asking me about whether they need to correct their dip angle for refraction and it takes a bit of time and patience to show them the relative size of the two effects for an observer only a few feet above sea level.
Keeping up with the grind