Time of sunrise and sunset

Description

Calculate time of sunrise/sunset for a given location and time of the year

Usage

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sunrise(day, month, year, longitude, latitude, zenith=96)
sunset(day, month, year, longitude, latitude, zenith=96)

Arguments

day

integer indicating day of month

month

integer indicating month number

year

integer indicating year

longitude

longitude in "decimal" degrees

latitude

latitude in "decimal" degrees

zenith

zenith in degrees

Value

number, time in hours

Note

The algorithm was taken from:

Note, however, that this function calculates the value of the sunrise in local mean time (solar time), not UTC.

See maptools to calculate sunrise/sunset in UTC/GMT ("clock" time).

Author(s)

Jacob van Etten

Examples

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# Example provided here: http://williams.best.vwh.net/sunrise_sunset_example.htm
sunrise(25, 6, 1990, -74.3, 40.9, zenith=(90+50/60))
# Earliest sunrise is before the solstice (June 20/21)
plot(1:30,sunrise(1:30,6,1990,-74.3,40.9))