sunvector: Solar vector
In insol: Solar Radiation

Description Usage Arguments Details Value Author(s) References See Also Examples

Calculates a unit vector in the direction of the sun from the observer position.

1	sunvector(jd, latitude, longitude, timezone)

`jd`	Julian Day and decimal fraction.
`latitude`	Latitude of observer in degrees and decimal fraction.
`longitude`	Longitude of observer in degrees and decimal fraction.
`timezone`	Time zone, west is negative.

To calculate the sunvector to the nearest hour, give the Julian Day with a precission better than 1/24; to approximate it to the nearest minute use decimal fractions smaller than 1/(24*60), and so on.

3 column matrix with the x, y , z coordinates of the sun vector.

Javier G. Corripio

Corripio, J. G.: 2003, Vectorial algebra algorithms for calculating terrain parameters from DEMs and the position of the sun for solar radiation modelling in mountainous terrain, International Journal of Geographical Information Science 17(1), 1-23.

sunpos

# Current solar vector at Greenwich observatory
sunvector(JD(Sys.time()),51.4778,-0.0017,0)

juneday = JD(seq(ISOdate(2019,6,21,0),ISOdate(2019,6,21,23,30),by='30 min'))
## Not run:  
# Path of the sun over Greenwich in summer
require(scatterplot3d)
scatterplot3d(sunvector(juneday,51.4778,-0.0017,0),
	ylim=c(-1,1),zlim=c(0,1),pch=8,color='orange')

## End(Not run)	
# print values 
options(digits=12)		# make sure decimals are printed
sunvector(juneday,51.4778,-0.0017,0)