NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Q: how to calculate refraction at higher altitudes on land?
From: Dov Kruger
Date: 2002 Feb 28, 14:26 -0500
From: Dov Kruger
Date: 2002 Feb 28, 14:26 -0500
Craig wrote: >If you can see the top of a nearby mountain, measure the angle above (or >below) horizontal, use the topographic map for mountain top coordinates, >waypoint mountain top and your position, obtain distance (easy with GPS), >use trigonometry for difference in opposite side, which is difference >between your height and mountain top, simple math, and voila! > This is an interesting idea, but you don't know your own altitude, and you therefore don't know the difference in altitude. You can use the current uncertain altitude as a starting point and iterate perhaps. If GPSs display the straight line distance between two points including altitude, then I am unaware of it. I do not even know if I can enter the altitude of a waypoint on my GPS. I don't think this is quite so easy as Craig says ;-)