NO CURVATURE
Elevation maps are often used in outdoor sports such as mountain climbing, bicycle competitions and other terrain sports where large distances are covered.
The Giro 'Italia, for example, has a route of 3449.6 km, which on a globe would mean a fall of approx. 762 km.
1264 km or a full 7 of the route's 21 stages consist of completely flat terrain; no mountains or hills (see table). This distance would, on a globe, mean a fall of over 80 km. The cyclists would definitely feel this huge incline/climb.
One way to see elevation over great distances, without being fooled by the illusion of the globe that is visible everywhere, is to simply enter two locations into Google Maps' directions feature and compare the elevation profile to the illusion of the curved path on a globe .
A classic long railway route is the Trans-Siberian Railway between Russian Moscow and Vladivostok of a staggering 8,585 km. As can be seen on Google's elevation profile on the left, it is a trip through mountains and valleys, but no curvature is represented at all, for the simple reason that earth's surface does not curve.
Here you can clearly see that the sea does not bend. The peaks in the elevation map are mountains in Turkey, the flat line shows the horizontal surface of the Mediterranean Sea.
Abyssal Planes
cover around 50% of the ocean floor and are among the flattest, smoothest and least explored regions on Earth.
Wikipedia
"flat surface, simplest of all geometrical surfaces," c. 1600, from Latin planum "flat surface, plane, level, plain," noun use of neuter of adjective planus "flat, level, even, plain, clear," from PIE *pla-no- (source also of Lithuanian plonas "thin;" Celtic *lanon "plain;" perhaps also Greek pelanos "sacrificial cake, a mixture offered to the gods, offering (of meal, honey, and oil) poured or spread "), suffixed form of root*pele-(2) "flat; to spread."
Plate Tectonics
(Encyclopedia Britannica)
*flat-
"to spread;" extension of root*pele-(2) "flat; to spread."
clan;flan;flat(adj.)"without curvature or projection;"flat(n.) "
Seafloor Spreading
(Encyclopedia Britannica)
The US weather service NOAA is trying to convince us here that level can be bent, that the sound channel (SOFAR), in which the sounds of whales travel thousands of kilometers, is bent and that the ocean floor is also slightly bent.
However, if you use common sense and real science, you understand that water surfaces are ALWAYS horizontal (think spirit level), that sound waves travel in straight lines and that the ocean floor is naturally parallel to the level ocean surface.
Here NASA shows a 360° view from America's highest mountain in the Andes - ACONCAGUA - Hundreds of kilometers without curvature either in terrain or water surface.
