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Re: Need Your Help
Posted by Birdman
on 00:22:50 11/04/09
In Reply to:
Re: Need Your Help posted by Tom H
At a distance of 80.15 miles the curvature of the earth is not trivial. Mount Charleston is 11,918 feet high and Stripped Butte is 4,786 feet in height for a difference of 7,132 feet. While one of the examples below from Google have less height difference than Mount Charleston and Stripped Butte and the distances are a bit longer the examples show that there would be a considerable change in the angle of observation from Stripped Butte to Mount Charleston because of the earth s curvature.
From Google.
It is often amazing to people that the curvature of the Earth shows up very clearly in the observed elevation angles of peaks. For example, Mt. San Gorgonio, Southern California's highest mountain at 11,490 loses 5000' of its apparent height when viewed at a distance of 87 miles, nearly halving the observed angle compared to the angle calculated assuming that the Earth is flat.
As you can see from the example of Mt. San Gorgonio observed at a distance of 87 miles, if you ignored the curvature of the Earth you would calculate an elevation angle that would be too large by nearly a factor of two. It is easy in Southern California to observe peaks at such distances. For example, the distance between San Jacinto and Mt. Wilson is 84 miles, and the elevation of San Jacinto as observed from Mt. Wilson turns out to be exactly 0.0° (ignoring atmospheric refraction - see below). The curvature of the Earth has exactly compensated for the increase in altitude of San Jacinto (10,804') over that of Mt. Wilson (5,710'). So instead of looking up to see San Jacinto from Mt. Wilson, one actually looks exactly along a level line.
. My Italian friend in San Pedro would quote Christopher Columbus: The world she s around, like a pizza.
Birdman
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