circ_sun {card}

Sunrise and Sunset Times

Description

Gets sunrise and sunset times based on date and location using the algorithm by the United States Naval Observatory. Uses the sensible default of official zenith for calculations. Requires geographic position in latitude and longitude to calculate sunrise or sunset. Uses the function lutz::tz_lookup_coords.

Usage

circ_sun(date, lat, lon, zenith = "official", sunset = FALSE)

Arguments

date

Vector of dates to calculate sun times for

lat

Latitude vector in degrees (e.g. Atlanta is 33.749), with negative values representing south. Each date must have a corresponding latitude.

lon

Longitude vector in degrees (e.g. Atlanta is -84.388), with negative values representing west

zenith

Zenith is the sun's zenith. There are several types, with different values. "official" = 90.8333 degrees, "civil" = 96 degrees, "nautical" = 102 degrees, "astronomical" = 108 degrees. They refer to the angle at which light allows for visibility, which can be affected by atmosphere and refraction.

sunset

Logical value for if sunset is wanted instead of sunrise. Default is FALSE (thus returning sunrises).

Value

Returns vector of sunrise/sunset times based on the date and location given. The time zone offset is included for the time zone represented by the latitude/longitude. The vector always returns UTC, but it has actually been corrected to the appropriate time-zone. Can use as.character() to strip the time zone away.

Examples

data("twins")
twins$lat <- 33.749
twins$lon <- -84.388

# Using latitude/longitude from Atlanta, GA, USA
twins$sunrise <- circ_sun(twins$date, twins$lat, twins$lon)