Calculates pi/2-the angle of the sun with the slope of the surface.

Calculates pi/2-the angle of the sun with the slope of the surface.

Usage

calczenithangle(Doy, t, Omega_g, Fi_gm, Long, Lat)

Arguments

Doy

day of the year

t

time of the day (hours, GMT)

Omega_g

slope azimuth angle (deg)

Fi_gm

slope of the surface (deg)

Long

Longitude (decimal)

Lat

Latitude (decimal)

Value

A list zenith.angles intended to contain:

Omega_s

Hour angle of the sun (rad).

Fi_s

"Classic" solar zenith angle, perpendicular to the horizontal plane (rad).

Fi_g

Projected slope of the surface, in the plane through the solar beam and the vertical (rad).

Fi_gs

Angle of the sun with the vector perpendicular to the (possibly sloped) surface, i.e. pi/2 minus the surface solar elevation angle (rad).

Details

Last updates: Jan 2003; Oct 2008 by Joris Timmermans (corrected equation of time); Oct 2012 (CvdT) comment: input time is GMT, not local time.

Author

Christiaan van der Tol  (Original version in Matlab)

Carlos Camino (Ported version into R)

Examples

if (FALSE) { # \dontrun{
zenith.angles <- calczenithangle(Doy = 180, t = 12, Omega_g = 210,
                                  Fi_gm = 30, Long = 13.75, Lat = 45.5)
} # }