File:TwilightLength.svg
Jump to navigation
Jump to search
Size of this PNG preview of this SVG file: 632 × 432 pixels. Other resolutions: 320 × 219 pixels | 640 × 437 pixels | 1,024 × 700 pixels | 1,280 × 875 pixels | 2,560 × 1,750 pixels.
Original file (SVG file, nominally 632 × 432 pixels, file size: 485 KB)
Captions
Captions
Add a one-line explanation of what this file represents
Summary
[edit]| Description | Approximate length of daylight, in hours, as a function of latitude and time of year. Here, the length of daylight is defined as the period from the beginning of civil twilight in the morning to the end of civil twilight in the evening. Morning civil twilight begins before sunrise when the sun is geometrically 6 degrees below the horizon and ends when the sun rises; evening civil twilight lasts from sunset until the sun is geometrically 6 degrees below the horizon. Civil twilight is roughly the period before sunrise and after sunset during which, under clear skies, outdoor activities can be carried out without artificial light. Times were calculated using the FORTRAN program sunae.f found at ftp://climate1.gsfc.nasa.gov/wiscombe/Solar_Rad/SunAngles/sunae.f. 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 start of the morning twilight was found by linearly interpolating to the time when the solar elevation was -6° and increasing; the end of the evening twilight was found the same way but for the elevation decreasing. |
| Date | |
| Source | Own work |
| Author | StephenHudson |
| Other versions |
[]
|
|
This SVG file contains embedded text that can be translated into your language, using any capable SVG editor, text editor or the SVG Translate tool. For more information see: About translating SVG files. |
Licensing
[edit]
|
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
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 05:11, 6 September 2007 | | 632 × 432 (485 KB) | StephenHudson (talk | contribs) | {{Information |Description=Length of civil twilight as a function of latitude and time of year. Civil twilight begins before sunrise when the sun is geometrically 6 degrees below the horizon and ends after sunset when the sun is geometrically 6 degrees be |
You cannot overwrite this file.
File usage on Commons
The following 5 pages use this file:
File usage on other wikis
The following other wikis use this file:
- Usage on www.wikidata.org
