# computeSunsetHourDoy: computeSunsetHourDoy In solartime: Utilities Dealing with Solar Time Such as Sun Position and Time of Sunrise

## Description

Compute the hour of sunrise for given day and coordinates

## Usage

 ```1 2``` ```computeSunsetHourDoy(doy, latDeg, longDeg = NA, timeZone = NA, isCorrectSolartime = TRUE) ```

## Arguments

 `doy` integer vector with day of year [DoY, 1..366] `latDeg` Latitude in (decimal) degrees `longDeg` Longitude in (decimal) degrees (not required if solar time is sufficient) `timeZone` Time zone (in hours) ahead of UTC (Central Europe is +1) (not required if solar time is sufficient) `isCorrectSolartime` sunrise hour is computed first for solar time (where noon is exactly at 12:00) If TRUE (default) then sunrise hour is converted to local winter time, based on timeZone and longitude.

## Value

numeric vector of length(doy) giving the time of sunset in hours after midnight. Polar night is indicated by 12h, polar day by 24h.

Thomas Wutzler

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10``` ```today <- as.POSIXlt(Sys.Date())\$yday (sunset <- computeSunsetHourDoy(today, latDeg = 51, isCorrectSolartime = FALSE)) (sunset <- computeSunsetHourDoy(today, latDeg = 51, longDeg = 11.586, timeZone = +1)) # doy <- 1:366 plot( computeSunsetHourDoy(doy, latDeg = 51, isCorrectSolartime = FALSE) ~ doy ) # north pole: daylength 0 and 24 hours plot( computeSunsetHourDoy( doy, latDeg = +80, isCorrectSolartime = FALSE) ~ doy ) plot( computeSunsetHourDoy( doy, latDeg = -80, isCorrectSolartime = FALSE) ~ doy ) ```

solartime documentation built on April 22, 2021, 5:10 p.m.