Solar Altitude / Winter-Design Sun Elevation

The sun's elevation angle above the horizon.

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Example

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You get

Details, formula, and sources

sin(altitude) = sin(lat) sin(dec) + cos(lat) cos(dec) cos(H), declination from Cooper's dec = 23.45 sin(360 (284+n)/365), hour angle H = 15 x (hours from solar noon); at solar noon altitude = 90 - |lat - dec|. At 40 deg N on the winter solstice the noon sun reaches only 26.6 deg and by 3 p.m. about 14 deg -- the winter-design elevation a shading, solar-access, tree, or setback study turns on. Feed it into a shadow length or PV row spacing. A negative value means the sun is below the horizon. True solar time and a flat horizon assumed; refraction and the equation of time are separate. The actual sun path governs.

dec = 23.45 sin(360 (284 + n)/365); H = 15 (hours from solar noon); sin(altitude) = sin(lat) sin(dec) + cos(lat) cos(dec) cos(H); at noon altitude = 90 - |lat - dec|.

The solar altitude (elevation) angle from the standard NOAA/ASHRAE solar-geometry relation, with the declination from Cooper's equation, by name.

The solar-position equations are public-domain solar geometry (NOAA/ASHRAE); the latitude, date, and time are the user's own site inputs.

Estimate. AHJ and licensed professional govern.

Field names used by the API: latitude_deg, day_of_year, altitude_deg, declination_deg

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