I was actually going to say the curvature kind of looked obvious from the airplane height :)
Maybe somebody can think about the maths that enables you to calculate the actual visible curvature of the earth. This might be harder than it seems (I had to think about this for a while and at 6am in the morning and it was beyond me!). Maybe tomorrow....
Well I mean, it's objectively curved, if you just put a ruler against it, but from the subjective mind, if you want to believe it's flat, it's not as absurd as you might think. Likewise, if we really want to believe a flat plane is round, our mind could give some concessions that way, too. So on a plane, it's simply not enough to be convinced, especially with weather conditions/atmosphere involved. Nice image though, not sure what you made it with...
How do you know it's not the ruler that's bent? Ever heard of Einstein's theory of rulerativity?
ahahah, the rulertivity law is far too complex for a working man like me to comprehend. Straight... curves??
Yeh I kind of went away from the original premise of your post there. Still it made me think what is the actual amount of visible curvature and how does one calculate the angle of dip as shown in the diagram. Btw that diagram was made using Blender. I just added a sphere and moved the camera to just above the top of the sphere.
Oh, nice. Feel free to calculate. I believe I've seen specific earth-curvature calculators in my previous flat earth debates. They love to use the angle calculators to prove it's impossible to see ships at a certain distance or whatever...