That makes sense. You're still short though.Originally Posted by John_Calif
To find your answer look west. Start playing around with the 14'ers in Colorado or California or try Alaska.
That makes sense. You're still short though.Originally Posted by John_Calif
To find your answer look west. Start playing around with the 14'ers in Colorado or California or try Alaska.
How about Denali in Alaska to Mount Logan in Canada? 386 miles apart, with a theoretical maximum sight distance of 380 miles. Just 6 miles short.
Following site may be of interest: http://www.heywhatsthat.com/.
They also have an FAQ that discusses distance to horizon, including refraction, at http://mintaka.sdsu.edu/GF/explain/a...r/horizon.html
Calculating maximum distance by this method is theoretically correct...but in practice is virtually impossible. Although two objects on top of their respective apexes may have a clear line of sight to each other, it cannot be assumed that those two objects would necessarily be able to "see" one another. If we are talking radio waves with microwave antennas, then yes. But a person on the summit of Mt.Washington being able to see only the topmost floor of the WTC (whilst the lower 109 stories are obstructed from view by the horizon) at a distance of 156.4 miles??? I hardly think so; the human eye definitely doesn't have the optical resolution necessary to resolve at that level of detail. Since 110 stories are much easier to resolve than just 1 floor, we can ignore the 49.7 figure and simply use 106.7 miles as a much more realistic distance.Originally Posted by John_Calif
Obviously, other factors such as atmospheric refraction will influence the final results, but that discussion is for another post...
Mark
You are riight also, the naked eye would never be able to see it but with the right magnification and perfect weather conditions I think it could be seen!!Originally Posted by mk10
Steve
Is there really any BAD weather???
Mark & Mark: Please read the earlier posts. The question being discussed no longer has anything to do with 'vision'. This discussion began with the query of the WTC being 'visible' from Mt Washington. But that impossibility was discarded and the discussion then morphed into only talking about the 'theoretical line of sight' between these two places. i.e. Is it true that there was no obstacle, including the earth itself, in between the WTC and the top of Mt Washington? (The answer to that question is 'no' because of the curvature of the earth.)
Now the question is: What is the longest distance between any two places (structures, peaks, etc...) in the US that have nothing but empty space along the straight line connecting them? And what are those two places?
Hobbes, thanks for the links- some cool info there. Bizarre that those explorers reported seeing peaks ~450 miles away from Kazakhstan.
The answer to our question must lie out West. Bill, I agree, Denali is a good candidate.
just wandered by, I will compute the horizon distance one of these days, but I'm quite sure that the distance for two unelevated points is 0.Originally Posted by Bill O
At elevation = 0, you can only look along a tangent line (well, tangent plane on a sphere) and thus can see no other point on the surface
XYZZY
That's absolutely true. I was thinking un-elevated as in 6 feet, in which case I was still wrong. I think its only 3 miles at 6 feet.Originally Posted by WEMT
This doesn't take into account atmospheric distortions that allow you to see farther than normal.
Just out of curiosity I used Topo! to generate a rough point to point plot from Mt Washington to the the WTC site and ran an elevation profile of the plot. I then drew a line from the Summit to a point guestimated at around 1,300ft. If the world were flat...
5MB jpeg map
Now, what happened to my math skills...
Bob
Here is my stab at this.
Assume a spherical earth, therefore a circular cross-section through the center of the earth.
The distance between the points represents an arc of the circular cross-section. The chord, a straight line between two points on a circle, represents the geometric line-of sight, (disregards atmospheric refraction).
The arc distance divided by the circumference times 360 gives you the angle represented by the arc. Each leg of this arc is the radius of the earth. Take 1/2 the arc angle. the cosine of 1/2 arc angle times the radius gives the distance from the center of the earth to the chord line. The difference between this distance and the radius gives the height of the visual interference due to the earths curvature at its maximum.
Take the average elevation of the two endpoints, if this is greater that the maximum visual interference then the two points could be seen. This assumes no topography in between. To calculate that I would have to return to the drawing board.
This is reflecting on my geometry from 1972, so I am not guaranteeing anything. Just a good mental exercise.