Solar altitude and azimuth gs & as--Algorithm 1.14Solar altitude is
defined as ¼/2-solar zenith angle (the angle between the centre of the sun and
the zenith). It is only approximately the angle of the centre of the sun above
the horizon, because near the horizon the apparent position of the sun is
affected by refraction in the atmosphere.
Solar azimuth is sometimes given as an angle from north, measured 0 to 2¼
clockwise; alternatively, it may be given as an angle from south, positive
towards the east, negative towards the west. The following formula gives the
solar azimuth as an angle from north. The angles are in radians.
- Solar declination, ds radians (algorithm 1.11)
- Solar hour angle, x radians (algorithm 1.13)
- Latitude of site, j radians (positive north of equator)
- CIE (1)
- Commission Internationale de lÕEclairage Guide to daylighting of
building interiors, draft 1990. Editor Nancy C Ruck. (Paris: to be published
by Commission Internationale de lÕEclairage).
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