en.wikipedia.org/wiki/Horizon

One typically sees further along the Earth's curved ... to some extent, to go around the curvature of the Earth. ... distance to the horizon from an observer close to the Earth's surface is about.

dizzib.github.io/earth/curve-calc

This app calculates how much a distant object is obscured by the earth's curvature, and makes ... d0 = Target distance. miles. Calculate. d1 = Horizon distance.

earthscience.stackexchange.com/questions/7283/how-high-must-one-be-for-the-curvature-of-the-earth-to-be-visible-to-the-eye

I would like to ask that at what distance from the Earth's surface the curvature of the Earth is visible. What layer of the atmosphere is this?

blogs.discovermagazine.com/badastronomy/2009/01/15/how-far-away-is-the-horizon

Jan 15, 2009 ... but the actual distance to the horizon is the arc length of the earth surface to the point, ..... Diminished of course by the curvature of the earth.

aty.sdsu.edu/explain/atmos_refr/horizon.html

The radius of the Earth is R, and the observer's eye is a height h above the point ... If h is in meters, that makes the distance to the geometric horizon 3.57 km ... because the relative curvature of the ray and the Earth's surface is all that matters .

science.howstuffworks.com/question198.htm

... large body of water is not actually flat at all -- it follows the curvature of the Earth. ... where "height above surface" is in feet and "distance to horizon" is in miles.

www.livescience.com/32111-how-far-away-is-the-horizon.html

Sep 12, 2012 ... Geometry tells us that the distance of the horizon – i.e. the farthest point the eye can see before Earth curves out beneath our view – depends ...

www.slate.com/blogs/bad_astronomy/2009/01/15/how_far_away_is_the_horizon.html

Jan 15, 2009 ... The horizon is a semi-mythical distance, used in poetry as a ... The dude standing on the Earth is a human of height h (not to scale, huge duh ...

www.metabunk.org/curve

Distance = 4 Miles (21120 Feet), View Height = 6 Feet (72 Inches) Radius = 3959 Miles (20903520 Feet). Horizon = 3 Miles (15838 Feet). Bulge = 2.67 Feet ...