Q: When you are flying 35,000 feet high, what are the maximum miles that we can see on a clear day? What about 40,000? 30,000?
A: There are many factors that affect the visible distance to the horizon, including the curvature of the earth and the effects of atmospheric refraction. To simplify the answer: if we only consider the earth’s curvature, the formula for distance in miles is 1.22 x the square root of the height of the aircraft in feet. I won’t make you do the math: At 10,000 feet, you can see 122 miles. At 30,000, visibility can be 211 miles; at 40,000 feet, you can see 244 miles. Of course, if you look “above” the horizon, you can see the sun at 93,000,000 miles and light years to the stars.
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