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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Refraction at the horizon.
From: Marcel Tschudin
Date: 2008 Mar 19, 11:20 +0200
From: Marcel Tschudin
Date: 2008 Mar 19, 11:20 +0200
... when I wrote last night the above comment related to the powers of temperature and pressure I should have added that I don't understand (yet) the reason for it. I therefore can't absolutely exclude an artefact of the calculation itself. However, thanks to Andrew T. Young the program could be tested beforehand carefully on several less and more critical bench mark calculations. The more critical cases were situations just at the edge before ducting occurs and situations with ducting, this for different observer positions. The results compared well. We found that the (small) differences we had resulted mainly from calculating/using gravity slightly different when calculating the pressure for the different layers. Andy used one same gravity value for all layers, calculated for an intermediate hight of the atmosphere (which is for his simulations absolutely sufficient) whereas in my model the gravity is calculated for an intermediate height within each layer. When I dug again in the files which were produced one year ago I selected "a" set of available graphs without finding out whether they really corresponded to the latest results found at that time. The aim was to show you what I meant with exponential behaviour, not more. It's clear that it would be interesting to understand the reason for this. Marcel --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---