Astronomical daylength So--Algorithm 1.15

Astronomical daylength, or astronomical sunshine duration, is defined as the period during which the solar altitude is greater than zero. The sun is actually hidden only when the solar altitude is below about -0.84 degrees (-0.0147 radians) due to the apparent radius of the sun (0.27 degrees) and atmospheric refraction.

Solar declination, ds radians (algorithm 1.11)
Latitude of site, j radians (positive north of equator)


Source Page(1)

  1. Page J K and Sharples S The SERC meteorological data base Volume II: algorithm manual 2nd Edition Department of Building Science University of Sheffield (1988)

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