Daylight Calculator

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This Demonstration shows the hours of daylight for a given latitude and the night and daylight halves of the globe for a given date and time.

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



The hours of daylight are calculated as the center of the sun's disk passes the horizon and its altitude is zero.

Snapshot 1: always 12 hours of daylight at the Equator

Snapshot 2: up to 24 hours of daylight above the Arctic Circle

Snapshot 3: some days, 0 hours of daylight below the Antarctic Circle

The world map is a resized version of the one developed by the NOAA. [1]

The sunset and sunrise definitions are taken from [2]


[1] "Marine Geology & Geophysics." National Geophysical Data Center. (Jun 21, 2011).

[2] Paul Schlyter, "How to compute rise/set times and altitude above horizon", Stockholm, Sweden

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