This model validates the computation of the solar declination, which is the angle between the equatorial plane and the solar beam. The time table solDecNOAA
outputs the solar declination according to the computation of the National Oceanic and Atmospheric Administration (NOAA), using their yearly calculator from http://www.esrl.noaa.gov/gmd/grad/solcalc/calcdetails.html. The values differ slightly because the equation in IDEAS.BoundaryConditions.SolarGeometry.BaseClasses.Declination is an approximation.