Here is a photo of South Coronado Island taken from the south looking north.
I'm having trouble verifying the highest elevation on the island. Wikipedia lists 722' (220m),
But on the same page is a topo map with contour lines only going up to 180-200m.
Google Earth depicts the north peak at 488' (149m) and the south peak at 580' (177m).
Another topographical resource has the north peak at 515' (157m) and the south peak at 654' (199m)
Nautical chart only lists the height of the beacon on the north peak at 672' (205m)
Clearly, the southern peak is higher than the northern peak, as is evident in my picture, which was taken from an elevation of 770'. So flat or curved, even at highest figure, South Coronado island would be below eye level. The only question is "how much below?"
But the horizon is well below that in both the uncertain hazy image and in the clear image. In fact, the horizon appears at the same angular location in both images. I intend on continuing to collect images of this view from this same location, so we'll be able to see how much variation there is in the horizon.
However, moving on from that, where IS "eye level" in this image? Google Earth seems to me to be flawed. I know Google has errant data for elevations of some military installations. Could it be that South Coronado Island (Mexican territory) simply hasn't been fully surveyed due to its inaccessibility? The height of the island summits are necessary for navigation, so I'd like to think you can trust the nautical chart. So if that beacon on the north summit is 672', the south peak is about 15% taller based on pixel comparisons of some lateral views of the island from Tijuana, which puts it right around 770'.
Is that wishful thinking? Did I just manipulate that estimate so that it could coincidentally be at eye level from my viewspot on Mount Soledad, 30+ miles away?
Suppose Google Earth is correct, and that peak is 488' in elevation? Assuming that, can +282' above that at that distance to 770' eye level be estimated?
The distance is 30.5 miles. On a globe with standard atmosphere, there would be a drop of 532' away from eye level. Roughly (very roughly), the island should appear below level eye sight by an amount about equal to its full height if we're assuming Google Earth is more correct than nautical charts.
Sound okay?
Anyone? Anyone? Bueller?