Which navigational error arises when sea horizon appears distorted due to thermal inversion during sextant measurement circa 1780?

💡 Explanation

When thermal inversion distorts the horizon, vertical refraction increases because the air density gradient bends light downwards, artificially elevating celestial objects, leading to an overestimate of altitude. Therefore, altitude inflation results, not bearing errors or parallax, which involve different mechanisms, nor index error, a problem of instrument calibration.

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