Solar Position Chart in Polar Coordinates

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This Demonstration charts, in polar coordinates, the position of the Sun at a given time for a given location on Earth.

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Locations on Earth are defined by latitude and longitude. The time is defined by the mean solar clock a number of days after January 1. The position of the Sun is defined by its altitude in the sky and its azimuth angle along the horizon.

This chart shows a circular horizon dividing the sky into day and night. You can see the path of the Sun during one day, the solar paths for the solstices and equinoxes, and the analemma for the selected location. The altitude can be read radially across concentric circles, from 0° at the horizon circle to 90° in the center. The azimuth is read clockwise along the horizon, starting from North.

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Contributed by: Erik Mahieu (February 2012)
Open content licensed under CC BY-NC-SA


Snapshots


Details

Time zones are calculated from longitude.

snapshot 1: at the equator

snapshot 2: at the North Pole

snapshot 3: in the Southern Hemisphere

The equations used for the declination and equation of time are from [1].

The equations used for the altitude and azimuth are from [2].

References

U.S. National Oceanographic and Atmospheric Administration. "General Solar Position Calculations." (Feb 1, 2012) www.srrb.noaa.gov/highlights/sunrise/solareqns.PDF.

U.S. Naval Observatory. "Computing Altitude and Azimuth from Greenwich Apparent Sidereal Time." (Jun 14, 2011) aa.usno.navy.mil/faq/docs/Alt_Az.php.



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