Visually discerning the curvature of the Earth.

  title={Visually discerning the curvature of the Earth.},
  author={David K. Lynch},
  journal={Applied optics},
  volume={47 34},
  • D. Lynch
  • Published 2008
  • Medicine, Physics
  • Applied optics
Reports and photographs claiming that visual observers can detect the curvature of the Earth from high mountains or high-flying commercial aircraft are investigated. Visual daytime observations show that the minimum altitude at which curvature of the horizon can be detected is at or slightly below 35,000 ft, providing that the field of view is wide (60 degrees ) and nearly cloud free. The high-elevation horizon is almost as sharp as the sea-level horizon, but its contrast is less than 10% that… Expand

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