Table Of Elevations Of Objects Above Sea Level, With Their Corresponding Distances Of Visibility
Description
This section is from the book "Scientific American Reference Book. A Manual for the Office, Household and Shop", by Albert A. Hopkins, A. Russell Bond. Also available from Amazon: Scientific American Reference Book.
Table Of Elevations Of Objects Above Sea Level, With Their Corresponding Distances Of Visibility
Height, in Feet. | Distance, in Nautical Miles. | Height, in Feet. | Distance, in Nautical Miles. |
5 | 2.555 | 50 | 8.081 |
10 | 3.614 | 100 | 11.428 |
15 | 4.426 | 250 | 18.070 |
20 | 5.111 | 500 | 25.555 |
25 | 5.714 | 1,000 | 36.140 |
Distances corresponding to heights not included in the above table may be found by the formula
in which H = the elevation, or height, in feet, of the object above sea-level, and D = the corresponding distance of visibility, in nautical miles. The formula is based on the mean curvature of the earth and is corrected for ordinary atmospheric refraction.
The distance of visibility of a light may be augmented by abnormal atmospheric refraction, which usually increases with the height of the barometer and a falling temperature.
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