File:DayLength.png
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Summary
| Description | Length of day (sunrise to sunset), in hours, as a function of latitude and time of year. Sunrise and sunset times were calculated using the FORTRAN program sunae.f found at ftp://climate1.gsfc.nasa.gov/wiscombe/Solar_Rad/SunAngles/sunae.f. Atmospheric refraction appropriate for the US Standard Atmosphere is applied at all latitudes, though the correction should vary by latitude and time of year. Contours are not necessarily smooth because of the 0.5-degree latitude spacing used in the calculations. Calculations were performed for the 365 days in 2007 on the Greenwich Meridian. For each minute during 2007 the sun's elevation (the angle between a flat horizon and the apparent location of the center of the sun, accounting for refraction) was calculated at -90, -89.5, -89, ..., 89.5, and 90° latitude and 0° longitude. The sunrise time was found by linearly interpolating to the time when the solar elevation was 0°, going from negative to positive; the sunset time was found the same way but for the elevation going from positive to negative. This ignores the fact that the diameter of the sun is about 0.5°, meaning the top of the sun does not drop below the horizon until the solar elevation is -0.25°. Ignoring the diameter of the sun slightly shortens the calculated length of the day, but the difference is not significant when plotted on this scale. |
| Date | |
| Source | Own work |
| Author | StephenHudson |
SVG version available, but it seems to load very slowly: Image:DayLength.svg
Licensing
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I, the copyright holder of this work, release this work into the public domain. This applies worldwide. In some countries this may not be legally possible; if so: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law. |
File history
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 21:37, 4 October 2016 | | 1,017 × 807 (100 KB) | Cmdrjameson | Compressed with pngout. Reduced by 69kB (41% decrease). |
| 03:54, 6 September 2007 |  | 1,017 × 807 (169 KB) | StephenHudson | {{Information |Description=Length of day (sunrise to sunset) as a function of latitude and time of year. Sunrise and sunset times were calculated using the FORTRAN program sunae.f found at ftp://climate1.gsfc.nasa.gov/wiscombe/Solar_Rad/SunAngles/sunae.f |
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